Commit Graph

93 Commits

Author SHA1 Message Date
Liujie Xie
2f55d5cbe2 ANDROID: vendor_hooks: Add hooks for mutex
Current might be preempt after spin_unlock(&lock->wait_lock),
we want to add a hook after wake_up_q(&wake_q) in which to
disable owner's privilege in scheduler.

Bug: 231647361
Change-Id: I3016da2fd31b8bdc8435df4e800f91381a64af4f
Signed-off-by: Liujie Xie <xieliujie@oppo.com>
2022-05-06 14:09:25 +08:00
Greg Kroah-Hartman
2300418cc6 Merge 5.10.65 into android12-5.10-lts
Changes in 5.10.65
	locking/mutex: Fix HANDOFF condition
	regmap: fix the offset of register error log
	regulator: tps65910: Silence deferred probe error
	crypto: mxs-dcp - Check for DMA mapping errors
	sched/deadline: Fix reset_on_fork reporting of DL tasks
	power: supply: axp288_fuel_gauge: Report register-address on readb / writeb errors
	crypto: omap-sham - clear dma flags only after omap_sham_update_dma_stop()
	sched/deadline: Fix missing clock update in migrate_task_rq_dl()
	rcu/tree: Handle VM stoppage in stall detection
	EDAC/mce_amd: Do not load edac_mce_amd module on guests
	posix-cpu-timers: Force next expiration recalc after itimer reset
	hrtimer: Avoid double reprogramming in __hrtimer_start_range_ns()
	hrtimer: Ensure timerfd notification for HIGHRES=n
	udf: Check LVID earlier
	udf: Fix iocharset=utf8 mount option
	isofs: joliet: Fix iocharset=utf8 mount option
	bcache: add proper error unwinding in bcache_device_init
	blk-throtl: optimize IOPS throttle for large IO scenarios
	nvme-tcp: don't update queue count when failing to set io queues
	nvme-rdma: don't update queue count when failing to set io queues
	nvmet: pass back cntlid on successful completion
	power: supply: smb347-charger: Add missing pin control activation
	power: supply: max17042_battery: fix typo in MAx17042_TOFF
	s390/cio: add dev_busid sysfs entry for each subchannel
	s390/zcrypt: fix wrong offset index for APKA master key valid state
	libata: fix ata_host_start()
	crypto: omap - Fix inconsistent locking of device lists
	crypto: qat - do not ignore errors from enable_vf2pf_comms()
	crypto: qat - handle both source of interrupt in VF ISR
	crypto: qat - fix reuse of completion variable
	crypto: qat - fix naming for init/shutdown VF to PF notifications
	crypto: qat - do not export adf_iov_putmsg()
	fcntl: fix potential deadlock for &fasync_struct.fa_lock
	udf_get_extendedattr() had no boundary checks.
	s390/kasan: fix large PMD pages address alignment check
	s390/pci: fix misleading rc in clp_set_pci_fn()
	s390/debug: keep debug data on resize
	s390/debug: fix debug area life cycle
	s390/ap: fix state machine hang after failure to enable irq
	power: supply: cw2015: use dev_err_probe to allow deferred probe
	m68k: emu: Fix invalid free in nfeth_cleanup()
	sched/numa: Fix is_core_idle()
	sched: Fix UCLAMP_FLAG_IDLE setting
	rcu: Fix to include first blocked task in stall warning
	rcu: Add lockdep_assert_irqs_disabled() to rcu_sched_clock_irq() and callees
	rcu: Fix stall-warning deadlock due to non-release of rcu_node ->lock
	m68k: Fix invalid RMW_INSNS on CPUs that lack CAS
	block: return ELEVATOR_DISCARD_MERGE if possible
	spi: spi-fsl-dspi: Fix issue with uninitialized dma_slave_config
	spi: spi-pic32: Fix issue with uninitialized dma_slave_config
	genirq/timings: Fix error return code in irq_timings_test_irqs()
	irqchip/loongson-pch-pic: Improve edge triggered interrupt support
	lib/mpi: use kcalloc in mpi_resize
	clocksource/drivers/sh_cmt: Fix wrong setting if don't request IRQ for clock source channel
	block: nbd: add sanity check for first_minor
	spi: coldfire-qspi: Use clk_disable_unprepare in the remove function
	irqchip/gic-v3: Fix priority comparison when non-secure priorities are used
	crypto: qat - use proper type for vf_mask
	certs: Trigger creation of RSA module signing key if it's not an RSA key
	tpm: ibmvtpm: Avoid error message when process gets signal while waiting
	x86/mce: Defer processing of early errors
	spi: davinci: invoke chipselect callback
	blk-crypto: fix check for too-large dun_bytes
	regulator: vctrl: Use locked regulator_get_voltage in probe path
	regulator: vctrl: Avoid lockdep warning in enable/disable ops
	spi: sprd: Fix the wrong WDG_LOAD_VAL
	spi: spi-zynq-qspi: use wait_for_completion_timeout to make zynq_qspi_exec_mem_op not interruptible
	EDAC/i10nm: Fix NVDIMM detection
	drm/panfrost: Fix missing clk_disable_unprepare() on error in panfrost_clk_init()
	drm/gma500: Fix end of loop tests for list_for_each_entry
	ASoC: mediatek: mt8183: Fix Unbalanced pm_runtime_enable in mt8183_afe_pcm_dev_probe
	media: TDA1997x: enable EDID support
	leds: is31fl32xx: Fix missing error code in is31fl32xx_parse_dt()
	soc: rockchip: ROCKCHIP_GRF should not default to y, unconditionally
	media: cxd2880-spi: Fix an error handling path
	drm/of: free the right object
	bpf: Fix a typo of reuseport map in bpf.h.
	bpf: Fix potential memleak and UAF in the verifier.
	drm/of: free the iterator object on failure
	gve: fix the wrong AdminQ buffer overflow check
	libbpf: Fix the possible memory leak on error
	ARM: dts: aspeed-g6: Fix HVI3C function-group in pinctrl dtsi
	arm64: dts: renesas: r8a77995: draak: Remove bogus adv7511w properties
	i40e: improve locking of mac_filter_hash
	soc: qcom: rpmhpd: Use corner in power_off
	libbpf: Fix removal of inner map in bpf_object__create_map
	gfs2: Fix memory leak of object lsi on error return path
	firmware: fix theoretical UAF race with firmware cache and resume
	driver core: Fix error return code in really_probe()
	ionic: cleanly release devlink instance
	media: dvb-usb: fix uninit-value in dvb_usb_adapter_dvb_init
	media: dvb-usb: fix uninit-value in vp702x_read_mac_addr
	media: dvb-usb: Fix error handling in dvb_usb_i2c_init
	media: go7007: fix memory leak in go7007_usb_probe
	media: go7007: remove redundant initialization
	media: rockchip/rga: use pm_runtime_resume_and_get()
	media: rockchip/rga: fix error handling in probe
	media: coda: fix frame_mem_ctrl for YUV420 and YVU420 formats
	media: atomisp: fix the uninitialized use and rename "retvalue"
	Bluetooth: sco: prevent information leak in sco_conn_defer_accept()
	6lowpan: iphc: Fix an off-by-one check of array index
	drm/amdgpu/acp: Make PM domain really work
	tcp: seq_file: Avoid skipping sk during tcp_seek_last_pos
	ARM: dts: meson8: Use a higher default GPU clock frequency
	ARM: dts: meson8b: odroidc1: Fix the pwm regulator supply properties
	ARM: dts: meson8b: mxq: Fix the pwm regulator supply properties
	ARM: dts: meson8b: ec100: Fix the pwm regulator supply properties
	net/mlx5e: Prohibit inner indir TIRs in IPoIB
	net/mlx5e: Block LRO if firmware asks for tunneled LRO
	cgroup/cpuset: Fix a partition bug with hotplug
	drm: mxsfb: Enable recovery on underflow
	drm: mxsfb: Increase number of outstanding requests on V4 and newer HW
	drm: mxsfb: Clear FIFO_CLEAR bit
	net: cipso: fix warnings in netlbl_cipsov4_add_std
	Bluetooth: mgmt: Fix wrong opcode in the response for add_adv cmd
	arm64: dts: renesas: rzg2: Convert EtherAVB to explicit delay handling
	arm64: dts: renesas: hihope-rzg2-ex: Add EtherAVB internal rx delay
	devlink: Break parameter notification sequence to be before/after unload/load driver
	net/mlx5: Fix missing return value in mlx5_devlink_eswitch_inline_mode_set()
	i2c: highlander: add IRQ check
	leds: lt3593: Put fwnode in any case during ->probe()
	leds: trigger: audio: Add an activate callback to ensure the initial brightness is set
	media: em28xx-input: fix refcount bug in em28xx_usb_disconnect
	media: venus: venc: Fix potential null pointer dereference on pointer fmt
	PCI: PM: Avoid forcing PCI_D0 for wakeup reasons inconsistently
	PCI: PM: Enable PME if it can be signaled from D3cold
	bpf, samples: Add missing mprog-disable to xdp_redirect_cpu's optstring
	soc: qcom: smsm: Fix missed interrupts if state changes while masked
	debugfs: Return error during {full/open}_proxy_open() on rmmod
	Bluetooth: increase BTNAMSIZ to 21 chars to fix potential buffer overflow
	PM: EM: Increase energy calculation precision
	selftests/bpf: Fix bpf-iter-tcp4 test to print correctly the dest IP
	drm/msm/mdp4: refactor HW revision detection into read_mdp_hw_revision
	drm/msm/mdp4: move HW revision detection to earlier phase
	drm/msm/dpu: make dpu_hw_ctl_clear_all_blendstages clear necessary LMs
	arm64: dts: exynos: correct GIC CPU interfaces address range on Exynos7
	counter: 104-quad-8: Return error when invalid mode during ceiling_write
	cgroup/cpuset: Miscellaneous code cleanup
	cgroup/cpuset: Fix violation of cpuset locking rule
	ASoC: Intel: Fix platform ID matching
	Bluetooth: fix repeated calls to sco_sock_kill
	drm/msm/dsi: Fix some reference counted resource leaks
	net/mlx5: Register to devlink ingress VLAN filter trap
	net/mlx5: Fix unpublish devlink parameters
	ASoC: rt5682: Implement remove callback
	ASoC: rt5682: Properly turn off regulators if wrong device ID
	usb: dwc3: meson-g12a: add IRQ check
	usb: dwc3: qcom: add IRQ check
	usb: gadget: udc: at91: add IRQ check
	usb: gadget: udc: s3c2410: add IRQ check
	usb: phy: fsl-usb: add IRQ check
	usb: phy: twl6030: add IRQ checks
	usb: gadget: udc: renesas_usb3: Fix soc_device_match() abuse
	selftests/bpf: Fix test_core_autosize on big-endian machines
	devlink: Clear whole devlink_flash_notify struct
	samples: pktgen: add missing IPv6 option to pktgen scripts
	Bluetooth: Move shutdown callback before flushing tx and rx queue
	PM: cpu: Make notifier chain use a raw_spinlock_t
	usb: host: ohci-tmio: add IRQ check
	usb: phy: tahvo: add IRQ check
	libbpf: Re-build libbpf.so when libbpf.map changes
	mac80211: Fix insufficient headroom issue for AMSDU
	locking/lockdep: Mark local_lock_t
	locking/local_lock: Add missing owner initialization
	lockd: Fix invalid lockowner cast after vfs_test_lock
	nfsd4: Fix forced-expiry locking
	arm64: dts: marvell: armada-37xx: Extend PCIe MEM space
	clk: staging: correct reference to config IOMEM to config HAS_IOMEM
	i2c: synquacer: fix deferred probing
	firmware: raspberrypi: Keep count of all consumers
	firmware: raspberrypi: Fix a leak in 'rpi_firmware_get()'
	usb: gadget: mv_u3d: request_irq() after initializing UDC
	mm/swap: consider max pages in iomap_swapfile_add_extent
	lkdtm: replace SCSI_DISPATCH_CMD with SCSI_QUEUE_RQ
	Bluetooth: add timeout sanity check to hci_inquiry
	i2c: iop3xx: fix deferred probing
	i2c: s3c2410: fix IRQ check
	i2c: fix platform_get_irq.cocci warnings
	i2c: hix5hd2: fix IRQ check
	gfs2: init system threads before freeze lock
	rsi: fix error code in rsi_load_9116_firmware()
	rsi: fix an error code in rsi_probe()
	ASoC: Intel: kbl_da7219_max98927: Fix format selection for max98373
	ASoC: Intel: Skylake: Leave data as is when invoking TLV IPCs
	ASoC: Intel: Skylake: Fix module resource and format selection
	mmc: sdhci: Fix issue with uninitialized dma_slave_config
	mmc: dw_mmc: Fix issue with uninitialized dma_slave_config
	mmc: moxart: Fix issue with uninitialized dma_slave_config
	bpf: Fix possible out of bound write in narrow load handling
	CIFS: Fix a potencially linear read overflow
	i2c: mt65xx: fix IRQ check
	i2c: xlp9xx: fix main IRQ check
	usb: ehci-orion: Handle errors of clk_prepare_enable() in probe
	usb: bdc: Fix an error handling path in 'bdc_probe()' when no suitable DMA config is available
	usb: bdc: Fix a resource leak in the error handling path of 'bdc_probe()'
	tty: serial: fsl_lpuart: fix the wrong mapbase value
	ASoC: wcd9335: Fix a double irq free in the remove function
	ASoC: wcd9335: Fix a memory leak in the error handling path of the probe function
	ASoC: wcd9335: Disable irq on slave ports in the remove function
	iwlwifi: follow the new inclusive terminology
	iwlwifi: skip first element in the WTAS ACPI table
	ice: Only lock to update netdev dev_addr
	ath6kl: wmi: fix an error code in ath6kl_wmi_sync_point()
	atlantic: Fix driver resume flow.
	bcma: Fix memory leak for internally-handled cores
	brcmfmac: pcie: fix oops on failure to resume and reprobe
	ipv6: make exception cache less predictible
	ipv4: make exception cache less predictible
	net: sched: Fix qdisc_rate_table refcount leak when get tcf_block failed
	net: qualcomm: fix QCA7000 checksum handling
	octeontx2-af: Fix loop in free and unmap counter
	octeontx2-af: Fix static code analyzer reported issues
	octeontx2-af: Set proper errorcode for IPv4 checksum errors
	ipv4: fix endianness issue in inet_rtm_getroute_build_skb()
	ASoC: rt5682: Remove unused variable in rt5682_i2c_remove()
	iwlwifi Add support for ax201 in Samsung Galaxy Book Flex2 Alpha
	f2fs: guarantee to write dirty data when enabling checkpoint back
	time: Handle negative seconds correctly in timespec64_to_ns()
	io_uring: IORING_OP_WRITE needs hash_reg_file set
	bio: fix page leak bio_add_hw_page failure
	tty: Fix data race between tiocsti() and flush_to_ldisc()
	perf/x86/amd/ibs: Extend PERF_PMU_CAP_NO_EXCLUDE to IBS Op
	x86/resctrl: Fix a maybe-uninitialized build warning treated as error
	Revert "KVM: x86: mmu: Add guest physical address check in translate_gpa()"
	KVM: s390: index kvm->arch.idle_mask by vcpu_idx
	KVM: x86: Update vCPU's hv_clock before back to guest when tsc_offset is adjusted
	KVM: VMX: avoid running vmx_handle_exit_irqoff in case of emulation
	KVM: nVMX: Unconditionally clear nested.pi_pending on nested VM-Enter
	ARM: dts: at91: add pinctrl-{names, 0} for all gpios
	fuse: truncate pagecache on atomic_o_trunc
	fuse: flush extending writes
	IMA: remove -Wmissing-prototypes warning
	IMA: remove the dependency on CRYPTO_MD5
	fbmem: don't allow too huge resolutions
	backlight: pwm_bl: Improve bootloader/kernel device handover
	clk: kirkwood: Fix a clocking boot regression
	Linux 5.10.65

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ie0b9306ba6ee4193de3200df7cdacaeba152b83e
2021-09-15 14:16:47 +02:00
Peter Zijlstra
97bc540bfb locking/mutex: Fix HANDOFF condition
[ Upstream commit 048661a1f963e9517630f080687d48af79ed784c ]

Yanfei reported that setting HANDOFF should not depend on recomputing
@first, only on @first state. Which would then give:

  if (ww_ctx || !first)
    first = __mutex_waiter_is_first(lock, &waiter);
  if (first)
    __mutex_set_flag(lock, MUTEX_FLAG_HANDOFF);

But because 'ww_ctx || !first' is basically 'always' and the test for
first is relatively cheap, omit that first branch entirely.

Reported-by: Yanfei Xu <yanfei.xu@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Yanfei Xu <yanfei.xu@windriver.com>
Link: https://lore.kernel.org/r/20210630154114.896786297@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-09-15 09:50:23 +02:00
Greg Kroah-Hartman
4968ab31d1 Merge 5.10.40 into android12-5.10
Changes in 5.10.40
	firmware: arm_scpi: Prevent the ternary sign expansion bug
	openrisc: Fix a memory leak
	tee: amdtee: unload TA only when its refcount becomes 0
	RDMA/siw: Properly check send and receive CQ pointers
	RDMA/siw: Release xarray entry
	RDMA/core: Prevent divide-by-zero error triggered by the user
	RDMA/rxe: Clear all QP fields if creation failed
	scsi: ufs: core: Increase the usable queue depth
	scsi: qedf: Add pointer checks in qedf_update_link_speed()
	scsi: qla2xxx: Fix error return code in qla82xx_write_flash_dword()
	RDMA/mlx5: Recover from fatal event in dual port mode
	RDMA/core: Don't access cm_id after its destruction
	nvmet: remove unused ctrl->cqs
	nvmet: fix memory leak in nvmet_alloc_ctrl()
	nvme-loop: fix memory leak in nvme_loop_create_ctrl()
	nvme-tcp: rerun io_work if req_list is not empty
	nvme-fc: clear q_live at beginning of association teardown
	platform/mellanox: mlxbf-tmfifo: Fix a memory barrier issue
	platform/x86: intel_int0002_vgpio: Only call enable_irq_wake() when using s2idle
	platform/x86: dell-smbios-wmi: Fix oops on rmmod dell_smbios
	RDMA/mlx5: Fix query DCT via DEVX
	RDMA/uverbs: Fix a NULL vs IS_ERR() bug
	tools/testing/selftests/exec: fix link error
	powerpc/pseries: Fix hcall tracing recursion in pv queued spinlocks
	ptrace: make ptrace() fail if the tracee changed its pid unexpectedly
	nvmet: seset ns->file when open fails
	perf/x86: Avoid touching LBR_TOS MSR for Arch LBR
	locking/lockdep: Correct calling tracepoints
	locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal
	powerpc: Fix early setup to make early_ioremap() work
	btrfs: avoid RCU stalls while running delayed iputs
	cifs: fix memory leak in smb2_copychunk_range
	misc: eeprom: at24: check suspend status before disable regulator
	ALSA: dice: fix stream format for TC Electronic Konnekt Live at high sampling transfer frequency
	ALSA: intel8x0: Don't update period unless prepared
	ALSA: firewire-lib: fix amdtp_packet tracepoints event for packet_index field
	ALSA: line6: Fix racy initialization of LINE6 MIDI
	ALSA: dice: fix stream format at middle sampling rate for Alesis iO 26
	ALSA: firewire-lib: fix calculation for size of IR context payload
	ALSA: usb-audio: Validate MS endpoint descriptors
	ALSA: bebob/oxfw: fix Kconfig entry for Mackie d.2 Pro
	ALSA: hda: fixup headset for ASUS GU502 laptop
	Revert "ALSA: sb8: add a check for request_region"
	ALSA: firewire-lib: fix check for the size of isochronous packet payload
	ALSA: hda/realtek: reset eapd coeff to default value for alc287
	ALSA: hda/realtek: Add some CLOVE SSIDs of ALC293
	ALSA: hda/realtek: Fix silent headphone output on ASUS UX430UA
	ALSA: hda/realtek: Add fixup for HP OMEN laptop
	ALSA: hda/realtek: Add fixup for HP Spectre x360 15-df0xxx
	uio_hv_generic: Fix a memory leak in error handling paths
	Revert "rapidio: fix a NULL pointer dereference when create_workqueue() fails"
	rapidio: handle create_workqueue() failure
	Revert "serial: mvebu-uart: Fix to avoid a potential NULL pointer dereference"
	nvme-tcp: fix possible use-after-completion
	x86/sev-es: Move sev_es_put_ghcb() in prep for follow on patch
	x86/sev-es: Invalidate the GHCB after completing VMGEXIT
	x86/sev-es: Don't return NULL from sev_es_get_ghcb()
	x86/sev-es: Use __put_user()/__get_user() for data accesses
	x86/sev-es: Forward page-faults which happen during emulation
	drm/amdgpu: Fix GPU TLB update error when PAGE_SIZE > AMDGPU_PAGE_SIZE
	drm/amdgpu: disable 3DCGCG on picasso/raven1 to avoid compute hang
	drm/amdgpu: update gc golden setting for Navi12
	drm/amdgpu: update sdma golden setting for Navi12
	powerpc/64s/syscall: Use pt_regs.trap to distinguish syscall ABI difference between sc and scv syscalls
	powerpc/64s/syscall: Fix ptrace syscall info with scv syscalls
	mmc: sdhci-pci-gli: increase 1.8V regulator wait
	xen-pciback: redo VF placement in the virtual topology
	xen-pciback: reconfigure also from backend watch handler
	ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry
	dm snapshot: fix crash with transient storage and zero chunk size
	kcsan: Fix debugfs initcall return type
	Revert "video: hgafb: fix potential NULL pointer dereference"
	Revert "net: stmicro: fix a missing check of clk_prepare"
	Revert "leds: lp5523: fix a missing check of return value of lp55xx_read"
	Revert "hwmon: (lm80) fix a missing check of bus read in lm80 probe"
	Revert "video: imsttfb: fix potential NULL pointer dereferences"
	Revert "ecryptfs: replace BUG_ON with error handling code"
	Revert "scsi: ufs: fix a missing check of devm_reset_control_get"
	Revert "gdrom: fix a memory leak bug"
	cdrom: gdrom: deallocate struct gdrom_unit fields in remove_gdrom
	cdrom: gdrom: initialize global variable at init time
	Revert "media: rcar_drif: fix a memory disclosure"
	Revert "rtlwifi: fix a potential NULL pointer dereference"
	Revert "qlcnic: Avoid potential NULL pointer dereference"
	Revert "niu: fix missing checks of niu_pci_eeprom_read"
	ethernet: sun: niu: fix missing checks of niu_pci_eeprom_read()
	net: stmicro: handle clk_prepare() failure during init
	scsi: ufs: handle cleanup correctly on devm_reset_control_get error
	net: rtlwifi: properly check for alloc_workqueue() failure
	ics932s401: fix broken handling of errors when word reading fails
	leds: lp5523: check return value of lp5xx_read and jump to cleanup code
	qlcnic: Add null check after calling netdev_alloc_skb
	video: hgafb: fix potential NULL pointer dereference
	vgacon: Record video mode changes with VT_RESIZEX
	vt_ioctl: Revert VT_RESIZEX parameter handling removal
	vt: Fix character height handling with VT_RESIZEX
	tty: vt: always invoke vc->vc_sw->con_resize callback
	drm/i915/gt: Disable HiZ Raw Stall Optimization on broken gen7
	openrisc: mm/init.c: remove unused memblock_region variable in map_ram()
	x86/Xen: swap NX determination and GDT setup on BSP
	nvme-multipath: fix double initialization of ANA state
	rtc: pcf85063: fallback to parent of_node
	x86/boot/compressed/64: Check SEV encryption in the 32-bit boot-path
	nvmet: use new ana_log_size instead the old one
	video: hgafb: correctly handle card detect failure during probe
	Bluetooth: SMP: Fail if remote and local public keys are identical
	Linux 5.10.40

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I4523cf43d1da6bea507e4027bd83bc491a574f41
2021-05-27 08:36:46 +02:00
Zqiang
e354e3744b locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal
[ Upstream commit 3a010c493271f04578b133de977e0e5dd2848cea ]

When a interruptible mutex locker is interrupted by a signal
without acquiring this lock and removed from the wait queue.
if the mutex isn't contended enough to have a waiter
put into the wait queue again, the setting of the WAITER
bit will force mutex locker to go into the slowpath to
acquire the lock every time, so if the wait queue is empty,
the WAITER bit need to be clear.

Fixes: 040a0a3710 ("mutex: Add support for wound/wait style locks")
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210517034005.30828-1-qiang.zhang@windriver.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-05-26 12:06:50 +02:00
Greg Kroah-Hartman
e92949726c Merge 5.10.28 into android12-5.10
Changes in 5.10.28
	arm64: mm: correct the inside linear map range during hotplug check
	bpf: Fix fexit trampoline.
	virtiofs: Fail dax mount if device does not support it
	ext4: shrink race window in ext4_should_retry_alloc()
	ext4: fix bh ref count on error paths
	fs: nfsd: fix kconfig dependency warning for NFSD_V4
	rpc: fix NULL dereference on kmalloc failure
	iomap: Fix negative assignment to unsigned sis->pages in iomap_swapfile_activate
	ASoC: rt1015: fix i2c communication error
	ASoC: rt5640: Fix dac- and adc- vol-tlv values being off by a factor of 10
	ASoC: rt5651: Fix dac- and adc- vol-tlv values being off by a factor of 10
	ASoC: sgtl5000: set DAP_AVC_CTRL register to correct default value on probe
	ASoC: es8316: Simplify adc_pga_gain_tlv table
	ASoC: soc-core: Prevent warning if no DMI table is present
	ASoC: cs42l42: Fix Bitclock polarity inversion
	ASoC: cs42l42: Fix channel width support
	ASoC: cs42l42: Fix mixer volume control
	ASoC: cs42l42: Always wait at least 3ms after reset
	NFSD: fix error handling in NFSv4.0 callbacks
	kernel: freezer should treat PF_IO_WORKER like PF_KTHREAD for freezing
	vhost: Fix vhost_vq_reset()
	io_uring: fix ->flags races by linked timeouts
	scsi: st: Fix a use after free in st_open()
	scsi: qla2xxx: Fix broken #endif placement
	staging: comedi: cb_pcidas: fix request_irq() warn
	staging: comedi: cb_pcidas64: fix request_irq() warn
	ASoC: rt5659: Update MCLK rate in set_sysclk()
	ASoC: rt711: add snd_soc_component remove callback
	thermal/core: Add NULL pointer check before using cooling device stats
	locking/ww_mutex: Simplify use_ww_ctx & ww_ctx handling
	locking/ww_mutex: Fix acquire/release imbalance in ww_acquire_init()/ww_acquire_fini()
	nvmet-tcp: fix kmap leak when data digest in use
	io_uring: imply MSG_NOSIGNAL for send[msg]()/recv[msg]() calls
	static_call: Align static_call_is_init() patching condition
	ext4: do not iput inode under running transaction in ext4_rename()
	io_uring: call req_set_fail_links() on short send[msg]()/recv[msg]() with MSG_WAITALL
	net: mvpp2: fix interrupt mask/unmask skip condition
	flow_dissector: fix TTL and TOS dissection on IPv4 fragments
	can: dev: move driver related infrastructure into separate subdir
	net: introduce CAN specific pointer in the struct net_device
	can: tcan4x5x: fix max register value
	brcmfmac: clear EAP/association status bits on linkdown events
	ath11k: add ieee80211_unregister_hw to avoid kernel crash caused by NULL pointer
	rtw88: coex: 8821c: correct antenna switch function
	netdevsim: dev: Initialize FIB module after debugfs
	iwlwifi: pcie: don't disable interrupts for reg_lock
	ath10k: hold RCU lock when calling ieee80211_find_sta_by_ifaddr()
	net: ethernet: aquantia: Handle error cleanup of start on open
	appletalk: Fix skb allocation size in loopback case
	net: ipa: remove two unused register definitions
	net: ipa: fix register write command validation
	net: wan/lmc: unregister device when no matching device is found
	net: 9p: advance iov on empty read
	bpf: Remove MTU check in __bpf_skb_max_len
	ACPI: tables: x86: Reserve memory occupied by ACPI tables
	ACPI: processor: Fix CPU0 wakeup in acpi_idle_play_dead()
	ALSA: usb-audio: Apply sample rate quirk to Logitech Connect
	ALSA: hda: Re-add dropped snd_poewr_change_state() calls
	ALSA: hda: Add missing sanity checks in PM prepare/complete callbacks
	ALSA: hda/realtek: fix a determine_headset_type issue for a Dell AIO
	ALSA: hda/realtek: call alc_update_headset_mode() in hp_automute_hook
	ALSA: hda/realtek: fix mute/micmute LEDs for HP 640 G8
	xtensa: fix uaccess-related livelock in do_page_fault
	xtensa: move coprocessor_flush to the .text section
	KVM: SVM: load control fields from VMCB12 before checking them
	KVM: SVM: ensure that EFER.SVME is set when running nested guest or on nested vmexit
	PM: runtime: Fix race getting/putting suppliers at probe
	PM: runtime: Fix ordering in pm_runtime_get_suppliers()
	tracing: Fix stack trace event size
	s390/vdso: copy tod_steering_delta value to vdso_data page
	s390/vdso: fix tod_steering_delta type
	mm: fix race by making init_zero_pfn() early_initcall
	drm/amdkfd: dqm fence memory corruption
	drm/amdgpu: fix offset calculation in amdgpu_vm_bo_clear_mappings()
	drm/amdgpu: check alignment on CPU page for bo map
	reiserfs: update reiserfs_xattrs_initialized() condition
	drm/imx: fix memory leak when fails to init
	drm/tegra: dc: Restore coupling of display controllers
	drm/tegra: sor: Grab runtime PM reference across reset
	vfio/nvlink: Add missing SPAPR_TCE_IOMMU depends
	pinctrl: rockchip: fix restore error in resume
	extcon: Add stubs for extcon_register_notifier_all() functions
	extcon: Fix error handling in extcon_dev_register
	firmware: stratix10-svc: reset COMMAND_RECONFIG_FLAG_PARTIAL to 0
	usb: dwc3: pci: Enable dis_uX_susphy_quirk for Intel Merrifield
	video: hyperv_fb: Fix a double free in hvfb_probe
	firewire: nosy: Fix a use-after-free bug in nosy_ioctl()
	usbip: vhci_hcd fix shift out-of-bounds in vhci_hub_control()
	USB: quirks: ignore remote wake-up on Fibocom L850-GL LTE modem
	usb: musb: Fix suspend with devices connected for a64
	usb: xhci-mtk: fix broken streams issue on 0.96 xHCI
	cdc-acm: fix BREAK rx code path adding necessary calls
	USB: cdc-acm: untangle a circular dependency between callback and softint
	USB: cdc-acm: downgrade message to debug
	USB: cdc-acm: fix double free on probe failure
	USB: cdc-acm: fix use-after-free after probe failure
	usb: gadget: udc: amd5536udc_pci fix null-ptr-dereference
	usb: dwc2: Fix HPRT0.PrtSusp bit setting for HiKey 960 board.
	usb: dwc2: Prevent core suspend when port connection flag is 0
	usb: dwc3: qcom: skip interconnect init for ACPI probe
	usb: dwc3: gadget: Clear DEP flags after stop transfers in ep disable
	soc: qcom-geni-se: Cleanup the code to remove proxy votes
	staging: rtl8192e: Fix incorrect source in memcpy()
	staging: rtl8192e: Change state information from u16 to u8
	driver core: clear deferred probe reason on probe retry
	drivers: video: fbcon: fix NULL dereference in fbcon_cursor()
	riscv: evaluate put_user() arg before enabling user access
	Revert "kernel: freezer should treat PF_IO_WORKER like PF_KTHREAD for freezing"
	bpf: Use NOP_ATOMIC5 instead of emit_nops(&prog, 5) for BPF_TRAMP_F_CALL_ORIG
	Linux 5.10.28

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ifdbbeda8de3ee22a7aa3f5d3b10becf0aba1a124
2021-04-09 09:29:17 +02:00
Waiman Long
905ef030bd locking/ww_mutex: Simplify use_ww_ctx & ww_ctx handling
[ Upstream commit 5de2055d31ea88fd9ae9709ac95c372a505a60fa ]

The use_ww_ctx flag is passed to mutex_optimistic_spin(), but the
function doesn't use it. The frequent use of the (use_ww_ctx && ww_ctx)
combination is repetitive.

In fact, ww_ctx should not be used at all if !use_ww_ctx.  Simplify
ww_mutex code by dropping use_ww_ctx from mutex_optimistic_spin() an
clear ww_ctx if !use_ww_ctx. In this way, we can replace (use_ww_ctx &&
ww_ctx) by just (ww_ctx).

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Link: https://lore.kernel.org/r/20210316153119.13802-2-longman@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-04-07 15:00:06 +02:00
xieliujie
80b4341d05 ANDROID: vendor_hooks: Add hooks for rwsem and mutex
Add hooks to apply oem's optimization of rwsem and mutex

Bug: 182237112
Signed-off-by: xieliujie <xieliujie@oppo.com>
Change-Id: I6332623732e2d6826b8b61087ca74e55393e0c3d
2021-03-10 21:18:26 +00:00
Sangmoon Kim
9ad8ff902e ANDROID: vendor_hooks: add waiting information for blocked tasks
- Add the hook to get mutex/rwsem information that the tasks
   are waiting for.

 - Add the hook to print messages for sched_show_task.

 - ANDROID_VENDOR_DATA_ARRAY added to task_struct

Bug: 162776704

Signed-off-by: Sangmoon Kim <sangmoon.kim@samsung.com>
Change-Id: Ib436fbd8d0ad509c3b5a73ea8f5170e0761a13fd
(cherry picked from commit b519ac4237)
2020-08-19 14:52:44 +00:00
Davidlohr Bueso
c571b72e2b Revert "locking/mutex: Complain upon mutex API misuse in IRQ contexts"
This ended up causing some noise in places such as rxrpc running in softirq.

The warning is misleading in this case as the mutex trylock and unlock
operations are done within the same context; and therefore we need not
worry about the PI-boosting issues that comes along with no single-owner
lock guarantees.

While we don't want to support this in mutexes, there is no way out of
this yet; so lets get rid of the WARNs for now, as it is only fair to
code that has historically relied on non-preemptible softirq guarantees.
In addition, changing the lock type is also unviable: exclusive rwsems
have the same issue (just not the WARN_ON) and counting semaphores
would introduce a performance hit as mutexes are a lot more optimized.

This reverts:

    a0855d24fc: ("locking/mutex: Complain upon mutex API misuse in IRQ contexts")

Fixes: a0855d24fc: ("locking/mutex: Complain upon mutex API misuse in IRQ contexts")
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Tested-by: David Howells <dhowells@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-afs@lists.infradead.org
Cc: linux-fsdevel@vger.kernel.org
Cc: will@kernel.org
Link: https://lkml.kernel.org/r/20191210220523.28540-1-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-12-11 00:27:43 +01:00
Davidlohr Bueso
a0855d24fc locking/mutex: Complain upon mutex API misuse in IRQ contexts
Add warning checks if mutex_trylock() or mutex_unlock() are used in
IRQ contexts, under CONFIG_DEBUG_MUTEXES=y.

While the mutex rules and semantics are explicitly documented, this allows
to expose any abusers and robustifies the whole thing.

While trylock and unlock are non-blocking, calling from IRQ context
is still forbidden (lock must be within the same context as unlock).

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Link: https://lkml.kernel.org/r/20191025033634.3330-1-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29 12:22:52 +01:00
Qian Cai
5facae4f35 locking/lockdep: Remove unused @nested argument from lock_release()
Since the following commit:

  b4adfe8e05 ("locking/lockdep: Remove unused argument in __lock_release")

@nested is no longer used in lock_release(), so remove it from all
lock_release() calls and friends.

Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: alexander.levin@microsoft.com
Cc: daniel@iogearbox.net
Cc: davem@davemloft.net
Cc: dri-devel@lists.freedesktop.org
Cc: duyuyang@gmail.com
Cc: gregkh@linuxfoundation.org
Cc: hannes@cmpxchg.org
Cc: intel-gfx@lists.freedesktop.org
Cc: jack@suse.com
Cc: jlbec@evilplan.or
Cc: joonas.lahtinen@linux.intel.com
Cc: joseph.qi@linux.alibaba.com
Cc: jslaby@suse.com
Cc: juri.lelli@redhat.com
Cc: maarten.lankhorst@linux.intel.com
Cc: mark@fasheh.com
Cc: mhocko@kernel.org
Cc: mripard@kernel.org
Cc: ocfs2-devel@oss.oracle.com
Cc: rodrigo.vivi@intel.com
Cc: sean@poorly.run
Cc: st@kernel.org
Cc: tj@kernel.org
Cc: tytso@mit.edu
Cc: vdavydov.dev@gmail.com
Cc: vincent.guittot@linaro.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1568909380-32199-1-git-send-email-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-09 12:46:10 +02:00
Peter Zijlstra
e57d143091 mutex: Fix up mutex_waiter usage
The patch moving bits into mutex.c was a little too much; by also
moving struct mutex_waiter a few less common CONFIGs would no longer
build.

Fixes: 5f35d5a66b ("locking/mutex: Make __mutex_owner static to mutex.c")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2019-08-08 09:09:25 +02:00
Mukesh Ojha
a037d26922 locking/mutex: Use mutex flags macro instead of hard code
Use the mutex flag macro instead of hard code value inside
__mutex_owner().

Signed-off-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mingo@redhat.com
Cc: will@kernel.org
Link: https://lkml.kernel.org/r/1564585504-3543-2-git-send-email-mojha@codeaurora.org
2019-08-06 12:49:16 +02:00
Mukesh Ojha
5f35d5a66b locking/mutex: Make __mutex_owner static to mutex.c
__mutex_owner() should only be used by the mutex api's.
So, to put this restiction let's move the __mutex_owner()
function definition from linux/mutex.h to mutex.c file.

There exist functions that uses __mutex_owner() like
mutex_is_locked() and mutex_trylock_recursive(), So
to keep legacy thing intact move them as well and
export them.

Move mutex_waiter structure also to keep it private to the
file.

Signed-off-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mingo@redhat.com
Cc: will@kernel.org
Link: https://lkml.kernel.org/r/1564585504-3543-1-git-send-email-mojha@codeaurora.org
2019-08-06 12:49:16 +02:00
Sebastian Andrzej Siewior
6c11c6e3d5 locking/mutex: Test for initialized mutex
An uninitialized/ zeroed mutex will go unnoticed because there is no
check for it. There is a magic check in the unlock's slowpath path which
might go unnoticed if the unlock happens in the fastpath.

Add a ->magic check early in the mutex_lock() and mutex_trylock() path.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190703092125.lsdf4gpsh2plhavb@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-07-25 15:39:27 +02:00
Mauro Carvalho Chehab
387b14684f docs: locking: convert docs to ReST and rename to *.rst
Convert the locking documents to ReST and add them to the
kernel development book where it belongs.

Most of the stuff here is just to make Sphinx to properly
parse the text file, as they're already in good shape,
not requiring massive changes in order to be parsed.

The conversion is actually:
  - add blank lines and identation in order to identify paragraphs;
  - fix tables markups;
  - add some lists markups;
  - mark literal blocks;
  - adjust title markups.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Federico Vaga <federico.vaga@vaga.pv.it>
2019-07-15 08:53:27 -03:00
Thomas Gleixner
457c899653 treewide: Add SPDX license identifier for missed files
Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 10:50:45 +02:00
Davidlohr Bueso
3bb5f4ac55 kernel/locking/mutex.c: remove caller signal_pending branch predictions
This is already done for us internally by the signal machinery.

Link: http://lkml.kernel.org/r/20181116002713.8474-2-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-04 13:13:48 -08:00
Thomas Hellstrom
e13e2366d8 locking/mutex: Fix mutex debug call and ww_mutex documentation
The following commit:

  08295b3b5b ("Implement an algorithm choice for Wound-Wait mutexes")

introduced a reference in the documentation to a function that was
removed in an earlier commit.

It also forgot to remove a call to debug_mutex_add_waiter() which is now
unconditionally called by __mutex_add_waiter().

Fix those bugs.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Fixes: 08295b3b5b ("Implement an algorithm choice for Wound-Wait mutexes")
Link: http://lkml.kernel.org/r/20180903140708.2401-1-thellstrom@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-10 10:05:10 +02:00
Thomas Hellstrom
08295b3b5b locking: Implement an algorithm choice for Wound-Wait mutexes
The current Wound-Wait mutex algorithm is actually not Wound-Wait but
Wait-Die. Implement also Wound-Wait as a per-ww-class choice. Wound-Wait
is, contrary to Wait-Die a preemptive algorithm and is known to generate
fewer backoffs. Testing reveals that this is true if the
number of simultaneous contending transactions is small.
As the number of simultaneous contending threads increases, Wait-Wound
becomes inferior to Wait-Die in terms of elapsed time.
Possibly due to the larger number of held locks of sleeping transactions.

Update documentation and callers.

Timings using git://people.freedesktop.org/~thomash/ww_mutex_test
tag patch-18-06-15

Each thread runs 100000 batches of lock / unlock 800 ww mutexes randomly
chosen out of 100000. Four core Intel x86_64:

Algorithm    #threads       Rollbacks  time
Wound-Wait   4              ~100       ~17s.
Wait-Die     4              ~150000    ~19s.
Wound-Wait   16             ~360000    ~109s.
Wait-Die     16             ~450000    ~82s.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Co-authored-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
2018-07-03 09:44:36 +02:00
Peter Ziljstra
55f036ca7e locking: WW mutex cleanup
Make the WW mutex code more readable by adding comments, splitting up
functions and pointing out that we're actually using the Wait-Die
algorithm.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Co-authored-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
2018-07-03 09:42:40 +02:00
Peter Zijlstra
c427f69564 locking/mutex: Optimize __mutex_trylock_fast()
Use try_cmpxchg to avoid the pointless TEST instruction..
And add the (missing) atomic_long_try_cmpxchg*() wrappery.

On x86_64 this gives:

0000000000000710 <mutex_lock>:						0000000000000710 <mutex_lock>:
 710:   65 48 8b 14 25 00 00    mov    %gs:0x0,%rdx                      710:   65 48 8b 14 25 00 00    mov    %gs:0x0,%rdx
 717:   00 00                                                            717:   00 00
                        715: R_X86_64_32S       current_task                                    715: R_X86_64_32S       current_task
 719:   31 c0                   xor    %eax,%eax                         719:   31 c0                   xor    %eax,%eax
 71b:   f0 48 0f b1 17          lock cmpxchg %rdx,(%rdi)                 71b:   f0 48 0f b1 17          lock cmpxchg %rdx,(%rdi)
 720:   48 85 c0                test   %rax,%rax                         720:   75 02                   jne    724 <mutex_lock+0x14>
 723:   75 02                   jne    727 <mutex_lock+0x17>             722:   f3 c3                   repz retq
 725:   f3 c3                   repz retq                                724:   eb da                   jmp    700 <__mutex_lock_slowpath>
 727:   eb d7                   jmp    700 <__mutex_lock_slowpath>       726:   66 2e 0f 1f 84 00 00    nopw   %cs:0x0(%rax,%rax,1)
 729:   0f 1f 80 00 00 00 00    nopl   0x0(%rax)                         72d:   00 00 00

On ARM64 this gives:

000000000000638 <mutex_lock>:						0000000000000638 <mutex_lock>:
     638:       d5384101        mrs     x1, sp_el0                           638:       d5384101        mrs     x1, sp_el0
     63c:       d2800002        mov     x2, #0x0                             63c:       d2800002        mov     x2, #0x0
     640:       f9800011        prfm    pstl1strm, [x0]                      640:       f9800011        prfm    pstl1strm, [x0]
     644:       c85ffc03        ldaxr   x3, [x0]                             644:       c85ffc03        ldaxr   x3, [x0]
     648:       ca020064        eor     x4, x3, x2                           648:       ca020064        eor     x4, x3, x2
     64c:       b5000064        cbnz    x4, 658 <mutex_lock+0x20>            64c:       b5000064        cbnz    x4, 658 <mutex_lock+0x20>
     650:       c8047c01        stxr    w4, x1, [x0]                         650:       c8047c01        stxr    w4, x1, [x0]
     654:       35ffff84        cbnz    w4, 644 <mutex_lock+0xc>             654:       35ffff84        cbnz    w4, 644 <mutex_lock+0xc>
     658:       b40000c3        cbz     x3, 670 <mutex_lock+0x38>            658:       b5000043        cbnz    x3, 660 <mutex_lock+0x28>
     65c:       a9bf7bfd        stp     x29, x30, [sp,#-16]!                 65c:       d65f03c0        ret
     660:       910003fd        mov     x29, sp                              660:       a9bf7bfd        stp     x29, x30, [sp,#-16]!
     664:       97ffffef        bl      620 <__mutex_lock_slowpath>          664:       910003fd        mov     x29, sp
     668:       a8c17bfd        ldp     x29, x30, [sp],#16                   668:       97ffffee        bl      620 <__mutex_lock_slowpath>
     66c:       d65f03c0        ret                                          66c:       a8c17bfd        ldp     x29, x30, [sp],#16
     670:       d65f03c0        ret                                          670:       d65f03c0        ret

Reported-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-04 10:02:39 +02:00
Matthew Wilcox
45dbac0e28 locking/mutex: Improve documentation
On Wed, Mar 14, 2018 at 01:56:31PM -0700, Andrew Morton wrote:

> My memory is weak and our documentation is awful.  What does
> mutex_lock_killable() actually do and how does it differ from
> mutex_lock_interruptible()?

Add kernel-doc for mutex_lock_killable() and mutex_lock_io().  Reword the
kernel-doc for mutex_lock_interruptible().

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: cl@linux.com
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/20180315115812.GA9949@bombadil.infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-20 08:07:41 +01:00
Mauro Carvalho Chehab
7b4ff1adb5 mutex, futex: adjust kernel-doc markups to generate ReST
There are a few issues on some kernel-doc markups that was
causing troubles with kernel-doc output on ReST format:

./kernel/futex.c:492: WARNING: Inline emphasis start-string without end-string.
./kernel/futex.c:1264: WARNING: Block quote ends without a blank line; unexpected unindent.
./kernel/futex.c:1721: WARNING: Block quote ends without a blank line; unexpected unindent.
./kernel/futex.c:2338: WARNING: Block quote ends without a blank line; unexpected unindent.
./kernel/futex.c:2426: WARNING: Block quote ends without a blank line; unexpected unindent.
./kernel/futex.c:2899: WARNING: Block quote ends without a blank line; unexpected unindent.
./kernel/futex.c:2972: WARNING: Block quote ends without a blank line; unexpected unindent.

Fix them.

No functional changes.

Acked-by: Darren Hart (VMware) <dvhart@infradead.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2017-05-16 08:43:25 -03:00
Ingo Molnar
b17b01533b sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>
We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:34 +01:00
Ingo Molnar
174cd4b1e5 sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>
Fix up affected files that include this signal functionality via sched.h.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:32 +01:00
Ingo Molnar
84f001e157 sched/headers: Prepare for new header dependencies before moving code to <linux/sched/wake_q.h>
We are going to split <linux/sched/wake_q.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/wake_q.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:26 +01:00
Linus Torvalds
42e1b14b6e Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Implement wraparound-safe refcount_t and kref_t types based on
     generic atomic primitives (Peter Zijlstra)

   - Improve and fix the ww_mutex code (Nicolai Hähnle)

   - Add self-tests to the ww_mutex code (Chris Wilson)

   - Optimize percpu-rwsems with the 'rcuwait' mechanism (Davidlohr
     Bueso)

   - Micro-optimize the current-task logic all around the core kernel
     (Davidlohr Bueso)

   - Tidy up after recent optimizations: remove stale code and APIs,
     clean up the code (Waiman Long)

   - ... plus misc fixes, updates and cleanups"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
  fork: Fix task_struct alignment
  locking/spinlock/debug: Remove spinlock lockup detection code
  lockdep: Fix incorrect condition to print bug msgs for MAX_LOCKDEP_CHAIN_HLOCKS
  lkdtm: Convert to refcount_t testing
  kref: Implement 'struct kref' using refcount_t
  refcount_t: Introduce a special purpose refcount type
  sched/wake_q: Clarify queue reinit comment
  sched/wait, rcuwait: Fix typo in comment
  locking/mutex: Fix lockdep_assert_held() fail
  locking/rtmutex: Flip unlikely() branch to likely() in __rt_mutex_slowlock()
  locking/rwsem: Reinit wake_q after use
  locking/rwsem: Remove unnecessary atomic_long_t casts
  jump_labels: Move header guard #endif down where it belongs
  locking/atomic, kref: Implement kref_put_lock()
  locking/ww_mutex: Turn off __must_check for now
  locking/atomic, kref: Avoid more abuse
  locking/atomic, kref: Use kref_get_unless_zero() more
  locking/atomic, kref: Kill kref_sub()
  locking/atomic, kref: Add kref_read()
  locking/atomic, kref: Add KREF_INIT()
  ...
2017-02-20 13:23:30 -08:00
Peter Zijlstra
b9c16a0e1f locking/mutex: Fix lockdep_assert_held() fail
In commit:

  659cf9f582 ("locking/ww_mutex: Optimize ww-mutexes by waking at most one waiter for backoff when acquiring the lock")

I replaced a comment with a lockdep_assert_held(). However it turns out
we hide that lock from lockdep for hysterical raisins, which results
in the assertion always firing.

Remove the old debug code as lockdep will easily spot the abuse it was
meant to catch, which will make the lock visible to lockdep and make
the assertion work as intended.

Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicolai Haehnle <Nicolai.Haehnle@amd.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 659cf9f582 ("locking/ww_mutex: Optimize ww-mutexes by waking at most one waiter for backoff when acquiring the lock")
Link: http://lkml.kernel.org/r/20170117150609.GB32474@worktop
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-30 11:42:59 +01:00
Tejun Heo
1460cb65a1 locking/mutex, sched/wait: Add mutex_lock_io()
We sometimes end up propagating IO blocking through mutexes; however,
because there currently is no way of annotating mutex sleeps as
iowait, there are cases where iowait and /proc/stat:procs_blocked
report misleading numbers obscuring the actual state of the system.

This patch adds mutex_lock_io() so that mutex sleeps can be marked as
iowait in those cases.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adilger.kernel@dilger.ca
Cc: jack@suse.com
Cc: kernel-team@fb.com
Cc: mingbo@fb.com
Cc: tytso@mit.edu
Link: http://lkml.kernel.org/r/1477673892-28940-4-git-send-email-tj@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:30:05 +01:00
Nicolai Hähnle
977625a693 locking/mutex: Initialize mutex_waiter::ww_ctx with poison when debugging
Help catch cases where mutex_lock is used directly on w/w mutexes, which
otherwise result in the w/w tasks reading uninitialized data.

Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-12-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:53 +01:00
Nicolai Hähnle
c516df978d locking/ww_mutex: Optimize ww-mutexes by yielding to other waiters from optimistic spin
Lock stealing is less beneficial for w/w mutexes since we may just end up
backing off if we stole from a thread with an earlier acquire stamp that
already holds another w/w mutex that we also need. So don't spin
optimistically unless we are sure that there is no other waiter that might
cause us to back off.

Median timings taken of a contention-heavy GPU workload:

Before:

  real    0m52.946s
  user    0m7.272s
  sys     1m55.964s

After:

  real    0m53.086s
  user    0m7.360s
  sys     1m46.204s

This particular workload still spends 20%-25% of CPU in mutex_spin_on_owner
according to perf, but my attempts to further reduce this spinning based on
various heuristics all lead to an increase in measured wall time despite
the decrease in sys time.

Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-11-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:52 +01:00
Nicolai Hähnle
25f13b4040 locking/ww_mutex: Re-check ww->ctx in the inner optimistic spin loop
In the following scenario, thread #1 should back off its attempt to lock
ww1 and unlock ww2 (assuming the acquire context stamps are ordered
accordingly).

    Thread #0               Thread #1
    ---------               ---------
                            successfully lock ww2
    set ww1->base.owner
                            attempt to lock ww1
                            confirm ww1->ctx == NULL
                            enter mutex_spin_on_owner
    set ww1->ctx

What was likely to happen previously is:

    attempt to lock ww2
    refuse to spin because
      ww2->ctx != NULL
    schedule()
                            detect thread #0 is off CPU
                            stop optimistic spin
                            return -EDEADLK
                            unlock ww2
                            wakeup thread #0
    lock ww2

Now, we are more likely to see:

                            detect ww1->ctx != NULL
                            stop optimistic spin
                            return -EDEADLK
                            unlock ww2
    successfully lock ww2

... because thread #1 will stop its optimistic spin as soon as possible.

The whole scenario is quite unlikely, since it requires thread #1 to get
between thread #0 setting the owner and setting the ctx. But since we're
idling here anyway, the additional check is basically free.

Found by inspection.

Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-10-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:51 +01:00
Peter Zijlstra
427b18207a locking/mutex: Improve inlining
Instead of inlining __mutex_lock_common() 5 times, once for each
{state,ww} variant. Reduce this to two, ww and !ww.

Then add __always_inline to mutex_optimistic_spin(), so that that will
get inlined all 4 remaining times, for all {waiter,ww} variants.

   text    data     bss     dec     hex filename

   6301       0       0    6301    189d defconfig-build/kernel/locking/mutex.o
   4053       0       0    4053     fd5 defconfig-build/kernel/locking/mutex.o
   4257       0       0    4257    10a1 defconfig-build/kernel/locking/mutex.o

This reduces total text size and better separates the ww and !ww mutex
code generation.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:48 +01:00
Nicolai Hähnle
659cf9f582 locking/ww_mutex: Optimize ww-mutexes by waking at most one waiter for backoff when acquiring the lock
The wait list is sorted by stamp order, and the only waiting task that may
have to back off is the first waiter with a context.

The regular slow path does not have to wake any other tasks at all, since
all other waiters that would have to back off were either woken up when
the waiter was added to the list, or detected the condition before they
added themselves.

Median timings taken of a contention-heavy GPU workload:

Without this series:

  real    0m59.900s
  user    0m7.516s
  sys     2m16.076s

With changes up to and including this patch:

  real    0m52.946s
  user    0m7.272s
  sys     1m55.964s

Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-9-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:44 +01:00
Nicolai Hähnle
200b187440 locking/ww_mutex: Notify waiters that have to back off while adding tasks to wait list
While adding our task as a waiter, detect if another task should back off
because of us.

With this patch, we establish the invariant that the wait list contains
at most one (sleeping) waiter with ww_ctx->acquired > 0, and this waiter
will be the first waiter with a context.

Since only waiters with ww_ctx->acquired > 0 have to back off, this allows
us to be much more economical with wakeups.

Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-8-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:43 +01:00
Nicolai Hähnle
6baa5c60a9 locking/ww_mutex: Add waiters in stamp order
Add regular waiters in stamp order. Keep adding waiters that have no
context in FIFO order and take care not to starve them.

While adding our task as a waiter, back off if we detect that there is
a waiter with a lower stamp in front of us.

Make sure to call lock_contended even when we back off early.

For w/w mutexes, being first in the wait list is only stable when
taking the lock without a context. Therefore, the purpose of the first
flag is split into two: 'first' remains to indicate whether we want to
spin optimistically, while 'handoff' indicates that we should be
prepared to accept a handoff.

For w/w locking with a context, we always accept handoffs after the
first schedule(), to handle the following sequence of events:

 1. Task #0 unlocks and hands off to Task #2 which is first in line

 2. Task #1 adds itself in front of Task #2

 3. Task #2 wakes up and must accept the handoff even though it is no
    longer first in line

Signed-off-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: =?UTF-8?q?Nicolai=20H=C3=A4hnle?= <Nicolai.Haehnle@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-7-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:42 +01:00
Nicolai Hähnle
c5470b22d1 locking/ww_mutex: Remove the __ww_mutex_lock*() inline wrappers
Keep the documentation in the header file since there is no good place
for it in mutex.c: there are two rather different implementations with
different EXPORT_SYMBOLs for each function.

Signed-off-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: =?UTF-8?q?Nicolai=20H=C3=A4hnle?= <Nicolai.Haehnle@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-6-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:41 +01:00
Nicolai Hähnle
ea9e0fb8fe locking/ww_mutex: Set use_ww_ctx even when locking without a context
We will add a new field to struct mutex_waiter.  This field must be
initialized for all waiters if any waiter uses the ww_use_ctx path.

So there is a trade-off: Keep ww_mutex locking without a context on
the faster non-use_ww_ctx path, at the cost of adding the
initialization to all mutex locks (including non-ww_mutexes), or avoid
the additional cost for non-ww_mutex locks, at the cost of adding
additional checks to the use_ww_ctx path.

We take the latter choice.  It may be worth eliminating the users of
ww_mutex_lock(lock, NULL), but there are a lot of them.

Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-5-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:40 +01:00
Nicolai Hähnle
3822da3ed0 locking/ww_mutex: Extract stamp comparison to __ww_mutex_stamp_after()
The function will be re-used in subsequent patches.

Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-4-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:39 +01:00
Peter Zijlstra
e274795ea7 locking/mutex: Fix mutex handoff
While reviewing the ww_mutex patches, I noticed that it was still
possible to (incorrectly) succeed for (incorrect) code like:

	mutex_lock(&a);
	mutex_lock(&a);

This was possible if the second mutex_lock() would block (as expected)
but then receive a spurious wakeup. At that point it would find itself
at the front of the queue, request a handoff and instantly claim
ownership and continue, since owner would point to itself.

Avoid this scenario and simplify the code by introducing a third low
bit to signal handoff pickup. So once we request handoff, unlock
clears the handoff bit and sets the pickup bit along with the new
owner.

This also removes the need for the .handoff argument to
__mutex_trylock(), since that becomes superfluous with PICKUP.

In order to guarantee enough low bits, ensure task_struct alignment is
at least L1_CACHE_BYTES (which seems a good ideal regardless).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 9d659ae14b ("locking/mutex: Add lock handoff to avoid starvation")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:38 +01:00
Davidlohr Bueso
642fa448ae sched/core: Remove set_task_state()
This is a nasty interface and setting the state of a foreign task must
not be done. As of the following commit:

  be628be095 ("bcache: Make gc wakeup sane, remove set_task_state()")

... everyone in the kernel calls set_task_state() with current, allowing
the helper to be removed.

However, as the comment indicates, it is still around for those archs
where computing current is more expensive than using a pointer, at least
in theory. An important arch that is affected is arm64, however this has
been addressed now [1] and performance is up to par making no difference
with either calls.

Of all the callers, if any, it's the locking bits that would care most
about this -- ie: we end up passing a tsk pointer to a lot of the lock
slowpath, and setting ->state on that. The following numbers are based
on two tests: a custom ad-hoc microbenchmark that just measures
latencies (for ~65 million calls) between get_task_state() vs
get_current_state().

Secondly for a higher overview, an unlink microbenchmark was used,
which pounds on a single file with open, close,unlink combos with
increasing thread counts (up to 4x ncpus). While the workload is quite
unrealistic, it does contend a lot on the inode mutex or now rwsem.

[1] https://lkml.kernel.org/r/1483468021-8237-1-git-send-email-mark.rutland@arm.com

== 1. x86-64 ==

Avg runtime set_task_state():    601 msecs
Avg runtime set_current_state(): 552 msecs

                                            vanilla                 dirty
Hmean    unlink1-processes-2      36089.26 (  0.00%)    38977.33 (  8.00%)
Hmean    unlink1-processes-5      28555.01 (  0.00%)    29832.55 (  4.28%)
Hmean    unlink1-processes-8      37323.75 (  0.00%)    44974.57 ( 20.50%)
Hmean    unlink1-processes-12     43571.88 (  0.00%)    44283.01 (  1.63%)
Hmean    unlink1-processes-21     34431.52 (  0.00%)    38284.45 ( 11.19%)
Hmean    unlink1-processes-30     34813.26 (  0.00%)    37975.17 (  9.08%)
Hmean    unlink1-processes-48     37048.90 (  0.00%)    39862.78 (  7.59%)
Hmean    unlink1-processes-79     35630.01 (  0.00%)    36855.30 (  3.44%)
Hmean    unlink1-processes-110    36115.85 (  0.00%)    39843.91 ( 10.32%)
Hmean    unlink1-processes-141    32546.96 (  0.00%)    35418.52 (  8.82%)
Hmean    unlink1-processes-172    34674.79 (  0.00%)    36899.21 (  6.42%)
Hmean    unlink1-processes-203    37303.11 (  0.00%)    36393.04 ( -2.44%)
Hmean    unlink1-processes-224    35712.13 (  0.00%)    36685.96 (  2.73%)

== 2. ppc64le ==

Avg runtime set_task_state():  938 msecs
Avg runtime set_current_state: 940 msecs

                                            vanilla                 dirty
Hmean    unlink1-processes-2      19269.19 (  0.00%)    30704.50 ( 59.35%)
Hmean    unlink1-processes-5      20106.15 (  0.00%)    21804.15 (  8.45%)
Hmean    unlink1-processes-8      17496.97 (  0.00%)    17243.28 ( -1.45%)
Hmean    unlink1-processes-12     14224.15 (  0.00%)    17240.21 ( 21.20%)
Hmean    unlink1-processes-21     14155.66 (  0.00%)    15681.23 ( 10.78%)
Hmean    unlink1-processes-30     14450.70 (  0.00%)    15995.83 ( 10.69%)
Hmean    unlink1-processes-48     16945.57 (  0.00%)    16370.42 ( -3.39%)
Hmean    unlink1-processes-79     15788.39 (  0.00%)    14639.27 ( -7.28%)
Hmean    unlink1-processes-110    14268.48 (  0.00%)    14377.40 (  0.76%)
Hmean    unlink1-processes-141    14023.65 (  0.00%)    16271.69 ( 16.03%)
Hmean    unlink1-processes-172    13417.62 (  0.00%)    16067.55 ( 19.75%)
Hmean    unlink1-processes-203    15293.08 (  0.00%)    15440.40 (  0.96%)
Hmean    unlink1-processes-234    13719.32 (  0.00%)    16190.74 ( 18.01%)
Hmean    unlink1-processes-265    16400.97 (  0.00%)    16115.22 ( -1.74%)
Hmean    unlink1-processes-296    14388.60 (  0.00%)    16216.13 ( 12.70%)
Hmean    unlink1-processes-320    15771.85 (  0.00%)    15905.96 (  0.85%)

x86-64 (known to be fast for get_current()/this_cpu_read_stable() caching)
and ppc64 (with paca) show similar improvements in the unlink microbenches.
The small delta for ppc64 (2ms), does not represent the gains on the unlink
runs. In the case of x86, there was a decent amount of variation in the
latency runs, but always within a 20 to 50ms increase), ppc was more constant.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: mark.rutland@arm.com
Link: http://lkml.kernel.org/r/1483479794-14013-5-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:16 +01:00
Davidlohr Bueso
d269a8b8c5 kernel/locking: Compute 'current' directly
This patch effectively replaces the tsk pointer dereference
(which is obviously == current), to directly use get_current()
macro. This is to make the removal of setting foreign task
states smoother and painfully obvious. Performance win on some
archs such as x86-64 and ppc64. On a microbenchmark that calls
set_task_state() vs set_current_state() and an inode rwsem
pounding benchmark doing unlink:

== 1. x86-64 ==

Avg runtime set_task_state():    601 msecs
Avg runtime set_current_state(): 552 msecs

                                            vanilla                 dirty
Hmean    unlink1-processes-2      36089.26 (  0.00%)    38977.33 (  8.00%)
Hmean    unlink1-processes-5      28555.01 (  0.00%)    29832.55 (  4.28%)
Hmean    unlink1-processes-8      37323.75 (  0.00%)    44974.57 ( 20.50%)
Hmean    unlink1-processes-12     43571.88 (  0.00%)    44283.01 (  1.63%)
Hmean    unlink1-processes-21     34431.52 (  0.00%)    38284.45 ( 11.19%)
Hmean    unlink1-processes-30     34813.26 (  0.00%)    37975.17 (  9.08%)
Hmean    unlink1-processes-48     37048.90 (  0.00%)    39862.78 (  7.59%)
Hmean    unlink1-processes-79     35630.01 (  0.00%)    36855.30 (  3.44%)
Hmean    unlink1-processes-110    36115.85 (  0.00%)    39843.91 ( 10.32%)
Hmean    unlink1-processes-141    32546.96 (  0.00%)    35418.52 (  8.82%)
Hmean    unlink1-processes-172    34674.79 (  0.00%)    36899.21 (  6.42%)
Hmean    unlink1-processes-203    37303.11 (  0.00%)    36393.04 ( -2.44%)
Hmean    unlink1-processes-224    35712.13 (  0.00%)    36685.96 (  2.73%)

== 2. ppc64le ==

Avg runtime set_task_state():  938 msecs
Avg runtime set_current_state: 940 msecs

                                            vanilla                 dirty
Hmean    unlink1-processes-2      19269.19 (  0.00%)    30704.50 ( 59.35%)
Hmean    unlink1-processes-5      20106.15 (  0.00%)    21804.15 (  8.45%)
Hmean    unlink1-processes-8      17496.97 (  0.00%)    17243.28 ( -1.45%)
Hmean    unlink1-processes-12     14224.15 (  0.00%)    17240.21 ( 21.20%)
Hmean    unlink1-processes-21     14155.66 (  0.00%)    15681.23 ( 10.78%)
Hmean    unlink1-processes-30     14450.70 (  0.00%)    15995.83 ( 10.69%)
Hmean    unlink1-processes-48     16945.57 (  0.00%)    16370.42 ( -3.39%)
Hmean    unlink1-processes-79     15788.39 (  0.00%)    14639.27 ( -7.28%)
Hmean    unlink1-processes-110    14268.48 (  0.00%)    14377.40 (  0.76%)
Hmean    unlink1-processes-141    14023.65 (  0.00%)    16271.69 ( 16.03%)
Hmean    unlink1-processes-172    13417.62 (  0.00%)    16067.55 ( 19.75%)
Hmean    unlink1-processes-203    15293.08 (  0.00%)    15440.40 (  0.96%)
Hmean    unlink1-processes-234    13719.32 (  0.00%)    16190.74 ( 18.01%)
Hmean    unlink1-processes-265    16400.97 (  0.00%)    16115.22 ( -1.74%)
Hmean    unlink1-processes-296    14388.60 (  0.00%)    16216.13 ( 12.70%)
Hmean    unlink1-processes-320    15771.85 (  0.00%)    15905.96 (  0.85%)

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: mark.rutland@arm.com
Link: http://lkml.kernel.org/r/1483479794-14013-4-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 11:14:14 +01:00
Pan Xinhui
05ffc95139 locking/mutex: Break out of expensive busy-loop on {mutex,rwsem}_spin_on_owner() when owner vCPU is preempted
An over-committed guest with more vCPUs than pCPUs has a heavy overload
in the two spin_on_owner. This blames on the lock holder preemption
issue.

Break out of the loop if the vCPU is preempted: if vcpu_is_preempted(cpu)
is true.

test-case:
perf record -a perf bench sched messaging -g 400 -p && perf report

before patch:
20.68%  sched-messaging  [kernel.vmlinux]  [k] mutex_spin_on_owner
 8.45%  sched-messaging  [kernel.vmlinux]  [k] mutex_unlock
 4.12%  sched-messaging  [kernel.vmlinux]  [k] system_call
 3.01%  sched-messaging  [kernel.vmlinux]  [k] system_call_common
 2.83%  sched-messaging  [kernel.vmlinux]  [k] copypage_power7
 2.64%  sched-messaging  [kernel.vmlinux]  [k] rwsem_spin_on_owner
 2.00%  sched-messaging  [kernel.vmlinux]  [k] osq_lock

after patch:
 9.99%  sched-messaging  [kernel.vmlinux]  [k] mutex_unlock
 5.28%  sched-messaging  [unknown]         [H] 0xc0000000000768e0
 4.27%  sched-messaging  [kernel.vmlinux]  [k] __copy_tofrom_user_power7
 3.77%  sched-messaging  [kernel.vmlinux]  [k] copypage_power7
 3.24%  sched-messaging  [kernel.vmlinux]  [k] _raw_write_lock_irq
 3.02%  sched-messaging  [kernel.vmlinux]  [k] system_call
 2.69%  sched-messaging  [kernel.vmlinux]  [k] wait_consider_task

Tested-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: boqun.feng@gmail.com
Cc: bsingharora@gmail.com
Cc: dave@stgolabs.net
Cc: kernellwp@gmail.com
Cc: konrad.wilk@oracle.com
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: rkrcmar@redhat.com
Cc: virtualization@lists.linux-foundation.org
Cc: will.deacon@arm.com
Cc: xen-devel-request@lists.xenproject.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1478077718-37424-4-git-send-email-xinhui.pan@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-11-22 12:48:10 +01:00
Waiman Long
194a6b5b9c sched/wake_q: Rename WAKE_Q to DEFINE_WAKE_Q
Currently the wake_q data structure is defined by the WAKE_Q() macro.
This macro, however, looks like a function doing something as "wake" is
a verb. Even checkpatch.pl was confused as it reported warnings like

  WARNING: Missing a blank line after declarations
  #548: FILE: kernel/futex.c:3665:
  +	int ret;
  +	WAKE_Q(wake_q);

This patch renames the WAKE_Q() macro to DEFINE_WAKE_Q() which clarifies
what the macro is doing and eliminates the checkpatch.pl warnings.

Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1479401198-1765-1-git-send-email-longman@redhat.com
[ Resolved conflict and added missing rename. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-11-21 10:29:01 +01:00
Christian Borntraeger
f2f09a4cee locking/core: Remove cpu_relax_lowlatency() users
With the s390 special case of a yielding cpu_relax() implementation gone,
we can now remove all users of cpu_relax_lowlatency() and replace them
with cpu_relax().

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Noam Camus <noamc@ezchip.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1477386195-32736-5-git-send-email-borntraeger@de.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-11-16 10:15:10 +01:00
Waiman Long
b341afb325 locking/mutex: Enable optimistic spinning of woken waiter
This patch makes the waiter that sets the HANDOFF flag start spinning
instead of sleeping until the handoff is complete or the owner
sleeps. Otherwise, the handoff will cause the optimistic spinners to
abort spinning as the handed-off owner may not be running.

Tested-by: Jason Low <jason.low2@hpe.com>
Signed-off-by: Waiman Long <Waiman.Long@hpe.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ding Tianhong <dingtianhong@huawei.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <Will.Deacon@arm.com>
Link: http://lkml.kernel.org/r/1472254509-27508-2-git-send-email-Waiman.Long@hpe.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-10-25 11:31:54 +02:00
Waiman Long
a40ca56577 locking/mutex: Simplify some ww_mutex code in __mutex_lock_common()
This patch removes some of the redundant ww_mutex code in
__mutex_lock_common().

Tested-by: Jason Low <jason.low2@hpe.com>
Signed-off-by: Waiman Long <Waiman.Long@hpe.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ding Tianhong <dingtianhong@huawei.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <Will.Deacon@arm.com>
Link: http://lkml.kernel.org/r/1472254509-27508-1-git-send-email-Waiman.Long@hpe.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-10-25 11:31:53 +02:00
Peter Zijlstra
5bbd7e6443 locking/mutex: Restructure wait loop
Doesn't really matter yet, but pull the HANDOFF and trylock out from
under the wait_lock.

The intention is to add an optimistic spin loop here, which requires
we do not hold the wait_lock, so shuffle code around in preparation.

Also clarify the purpose of taking the wait_lock in the wait loop, its
tempting to want to avoid it altogether, but the cancellation cases
need to to avoid losing wakeups.

Suggested-by: Waiman Long <waiman.long@hpe.com>
Tested-by: Jason Low <jason.low2@hpe.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-10-25 11:31:53 +02:00