There is an allocation with GFP_KERNEL flag in mos7840_write(),
while it may be called from interrupt context.
Follow-up for commit 1912528376 ("USB: kobil_sct: fix non-atomic
allocation in write path")
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
There is an allocation with GFP_KERNEL flag in mos7720_write(),
while it may be called from interrupt context.
Follow-up for commit 1912528376 ("USB: kobil_sct: fix non-atomic
allocation in write path")
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Johan writes:
USB-serial fixes for v4.8-rc2
Here is a fix of a memory leak in a driver-registration error path, and
some new device ids.
Signed-off-by: Johan Hovold <johan@kernel.org>
In sg_timeout(), req->status is set to "-ETIMEDOUT" before calling
into usb_sg_cancel(). usb_sg_cancel() will do nothing and return
directly if req->status has been set to a non-zero value. This will
cause driver hang whenever transfer time out is triggered.
This patch fixes this issue. It could be backported to stable kernel
with version later than v3.15.
Cc: stable@vger.kernel.org # 3.15+
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Felipe writes:
usb: fixes for v4.8-rc1
First set of fixes for v4.8-rc cycle. Again, dwc3 is
the most active driver with over 60% of this pull
request touching it.
The most important fixes are related to scatterlist
usage with dwc3. Before this pull request, we were
increment request->actual multiple times and this
would result in request->actual being larger than
request->length.
Also, if a we received a short packet midway through
processing a scatterlist, we were not clearning HWO
bit as we should.
Other than the large dwc3 scatterlist fixes, we have
a new Device ID for Intel's Kabylake silicon.
Other drivers, such as fsl_qe_udc and renesas udc,
also got a few minor fixes. Details are in shortlog.
stop consuming TRBs when we reach one with HWO bit
already set. This will prevent us from prematurely
retiring a TRB.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
According to Synopsys Databook 2.60a, section 8.3.4,
it's stated that:
The LST bit should be set to 0 (isochronous
transfers normally continue until the
endpoint is removed entirely, at which time
an End Transfer command is used to stop the
transfer).
This patch makes sure that detail is observed and
fixes a regression with Android Audio playback
caused by recent changes to DWC3 gadget.
Signed-off-by: Janusz Dziedzic <januszx.dziedzic@linux.intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
When rndis data transfer is in progress, some Windows7 Host PC is not
sending the GET_ENCAPSULATED_RESPONSE command for receiving the response
for the previous SEND_ENCAPSULATED_COMMAND processed.
The rndis function driver appends each response for the
SEND_ENCAPSULATED_COMMAND in a queue. As the above process got corrupted,
the Host sends a REMOTE_NDIS_RESET_MSG command to do a soft-reset.
As the rndis response queue is not freed, the previous response is sent
as a part of this REMOTE_NDIS_RESET_MSG's reset response and the Host
block any more Rndis transfers.
Hence free the rndis response queue as a part of this soft-reset so that
the correct response for REMOTE_NDIS_RESET_MSG is sent properly during the
response command.
Signed-off-by: Rajkumar Raghupathy <raghup@codeaurora.org>
Signed-off-by: Xerox Lin <xerox_lin@htc.com>
[AmitP: Cherry-picked this patch and folded other relevant
fixes from Android common kernel android-4.4]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
The udc device needs to be deleted if error occurs
Fixes: 855ed04a37 ("usb: gadget: udc-core: independent registration of
gadgets and gadget drivers")
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
In 'composite_os_desc_req_prepare', if one of the memory allocations fail,
0 will be returned, which means success.
We should return -ENOMEM instead.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
When reading synchronously from a non-zero endpoint, gadgetfs will
return -EFAULT even if the read succeeds, due to a bad check of the
copy_to_iter() return value.
This fix compares the return value of copy_to_iter to the amount of
bytes that was passed, and only fails if they are not the same.
Signed-off-by: Binyamin Sharet <s.binyamin@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
For case 14 and case 21, their correct return value is the number
of bytes transferred, so it is a positive integer. But in usbtest_ioctl,
it takes non-zero as false return value for usbtest_do_ioctl, so
it will treat the correct test as wrong test, then the time on
tests will be the minus value.
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Cc: stable <stable@vger.kernel.org>
Fixes: 18fc4ebdc7 ("usb: misc: usbtest: Remove timeval usage")
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Add missing platform_set_drvdata() in dwc3_of_simple_probe(), otherwise
calling platform_get_drvdata() in remove returns NULL.
This is detected by Coccinelle semantic patch.
Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Add missing platform_set_drvdata() in omap_otg_probe(), otherwise
calling platform_get_drvdata() in remove returns NULL.
This is detected by Coccinelle semantic patch.
Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
There may be a race condition if f_fs calls unregister_gadget_item in
ffs_closed() when unregister_gadget is called by UDC store at the same time.
this leads to a kernel NULL pointer dereference:
[ 310.644928] Unable to handle kernel NULL pointer dereference at virtual address 00000004
[ 310.645053] init: Service 'adbd' is being killed...
[ 310.658938] pgd = c9528000
[ 310.662515] [00000004] *pgd=19451831, *pte=00000000, *ppte=00000000
[ 310.669702] Internal error: Oops: 817 [#1] PREEMPT SMP ARM
[ 310.675211] Modules linked in:
[ 310.678294] CPU: 0 PID: 1537 Comm: ->transport Not tainted 4.1.15-03725-g793404c #2
[ 310.685958] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 310.692493] task: c8e24200 ti: c945e000 task.ti: c945e000
[ 310.697911] PC is at usb_gadget_unregister_driver+0xb4/0xd0
[ 310.703502] LR is at __mutex_lock_slowpath+0x10c/0x16c
[ 310.708648] pc : [<c075efc0>] lr : [<c0bfb0bc>] psr: 600f0113
<snip..>
[ 311.565585] [<c075efc0>] (usb_gadget_unregister_driver) from [<c075e2b8>] (unregister_gadget_item+0x1c/0x34)
[ 311.575426] [<c075e2b8>] (unregister_gadget_item) from [<c076fcc8>] (ffs_closed+0x8c/0x9c)
[ 311.583702] [<c076fcc8>] (ffs_closed) from [<c07736b8>] (ffs_data_reset+0xc/0xa0)
[ 311.591194] [<c07736b8>] (ffs_data_reset) from [<c07738ac>] (ffs_data_closed+0x90/0xd0)
[ 311.599208] [<c07738ac>] (ffs_data_closed) from [<c07738f8>] (ffs_ep0_release+0xc/0x14)
[ 311.607224] [<c07738f8>] (ffs_ep0_release) from [<c023e030>] (__fput+0x80/0x1d0)
[ 311.614635] [<c023e030>] (__fput) from [<c014e688>] (task_work_run+0xb0/0xe8)
[ 311.621788] [<c014e688>] (task_work_run) from [<c010afdc>] (do_work_pending+0x7c/0xa4)
[ 311.629718] [<c010afdc>] (do_work_pending) from [<c010770c>] (work_pending+0xc/0x20)
for functions using functionFS, i.e. android adbd will close /dev/usb-ffs/adb/ep0
when usb IO thread fails, but switch adb from on to off also triggers write
"none" > UDC. These 2 operations both call unregister_gadget, which will lead
to the panic above.
add a mutex before calling unregister_gadget for api used in f_fs.
Signed-off-by: Winter Wang <wente.wang@nxp.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
dev->port_usb is checked for null pointer at above code, so dev->port_usb
might be null, fix it by adding null pointer check.
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
cdev->config is checked for null pointer at above code, so cdev->config
might be null, fix it by adding null pointer check.
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This patch fixes an issue that isochronous transfer's data is possible to
be lost as a workaround. Since this driver uses a workqueue to start
the dmac, the transfer is possible to be delayed when system load is high.
Fixes: 6e4b74e469 ("usb: renesas: fix scheduling in atomic context bug")
Cc: <stable@vger.kernel.org> # v3.4+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This patch fixes an issue that unexpected BRDY interruption happens
when the usb_ep_{enable,disable}() are called with different direction.
In this case, the driver will cause the following message:
renesas_usbhs e6590000.usb: irq_ready run_error 1 : -16
This issue causes the followings:
1) A pipe is enabled as transmission
2) The pipe sent a data
3) The pipe is disabled and re-enabled as reception.
4) The pipe got a queue
Since the driver doesn't clear the BRDYSTS flags after 2) above, the issue
happens. If we add such clearing the flags into the driver, the code will
become complicate. So, this patch clears the BRDYSTS flag of reception in
usbhsg_ep_enable() to avoid complicate.
Cc: <stable@vger.kernel.org> # v4.1+ (usbhs_xxxsts_clear() is needed)
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Since R-Car Gen3 SoC has the USB-DMAC, this driver should set
dparam->has_usb_dmac to 1. Otherwise, behavior of this driver and
the usb-dmac driver will be mismatch, then sometimes receiving data will
be corrupt.
Fixes: de18757e27 ("usb: renesas_usbhs: add R-Car Gen3 power control")
Cc: <stable@vger.kernel.org> # v4.5+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
DWC3 has one interesting peculiarity with chained
transfers. If we setup N chained transfers and we
get a short packet before processing all N TRBs,
DWC3 will (conditionally) issue a XferComplete or
XferInProgress event and retire all TRBs from the
one which got a short packet to the last without
clearing their HWO bits.
This means SW must clear HWO bit manually, which
this patch is doing.
Cc: <stable@vger.kernel.org>
Cc: Brian E Rogers <brian.e.rogers@intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
When using SG lists, we would end up setting
request->actual to:
num_mapped_sgs * (request->length - count)
Let's fix that up by incrementing request->actual
only once.
Cc: <stable@vger.kernel.org>
Reported-by: Brian E Rogers <brian.e.rogers@intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Implemented queued response handling. This queue is processed every time the
WDM_READ flag is cleared.
In case of a read error, userspace may not actually read the data, since the
driver returns an error through wdm_poll. After this, the underlying device may
attempt to send us more data, but the queue is not processed. While userspace is
also blocked, because the read error is never cleared.
After this patch, we proactively process the queue on a read error. If there was
an outstanding response to handle, that will clear the error (or go through the
same logic again, if another read error occurs). If there was no outstanding
response, this will bring the queue size back to 0, unblocking a future response
from the underlying device.
Signed-off-by: Robert Foss <robert.foss@collabora.com>
Tested-by: Robert Foss <robert.foss@collabora.com>
Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Modification to Kconfig, vhci_hc.c, vhci.h and vhci_sysfs.c.
1. kernel config
Followings are added.
USBIP_VHCI_HC_PORTS: Number of ports per USB/IP virtual host
controller. The default is 8 - same as current VHCI_NPORTS.
USBIP_VHCI_NR_HCS: Number of USB/IP virtual host controllers. The
default is 1. This paratmeter is replaced with USBIP_VHCI_INIT_HCS and
USBIP_VHCI_MAX_HCS included in succeeding dynamic extension patch.
2. the_controller to controllers
the_controller is changed to vhci_pdevs: array of struct
platform_device.
3. vhci_sysfs.c
Sysfs structure is changed as following.
BEFORE:
/sys/devices/platform
+-- vhci
+-- status
+-- attach
+-- detach
+-- usbip_debug
AFTER: example for CONFIG_USBIP_NR_HCS=4
/sys/devices/platform
+-- vhci
| +-- nports
| +-- status
| +-- status.1
| +-- status.2
| +-- status.3
| +-- attach
| +-- detach
| +-- usbip_debug
+-- vhci.1
+-- vhci.2
+-- vhci.3
vhci[.N] is shown for each host controller kobj. vhch.1, vhci.2, ...
are shown only when CONFIG_USBIP_NR_HCS is more than 1. Only 'vhci'
(without number) has user space interfaces. 'nports' is newly added to
give ports-per-controller and number of controlles. Before that, number
of ports is acquired by reading status lines. Status is divided for
each controller to avoid page size (4KB) limitation.
Old userspace tool binaries work with the first status within the first
controller.
Inconsistency between status header and content is fixed.
4th and 5th column are
header: "dev bus"
content(unused): "000 000"
content(used): "%08x", devid
Only 1st and 2nd column are used by program. In old version, sscanf()
in parse_status expect no bus column. And bus_id string is shown in the
last column. Then bus in the header is removed and unused content is
replaced with 8 zeros. The sscanf() expects more than 5 columns and new
has 6 columns so there's no compatibility issue in this change.
Signed-off-by: Nobuo Iwata <nobuo.iwata@fujixerox.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The whole Kconfig entries of the USB subsystem are surrounded with
"if USB_SUPPORT" ... "endif", so CONFIG_USB_SUPPORT=y is surely met
when these two Kconfig options are visible.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
GPIO control register is divided into IOPINS1 and IOPINS2.
And low 4-bit of register is controls output.
So, this patch fixes wrong mask of GPIO output.
Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Hans de Goede has reported a difficulty in the Linux port of libusb.
When a device is removed, the poll() system call in usbfs starts
returning POLLERR as soon as udev->state is set to
USB_STATE_NOTATTACHED, but the outstanding URBs are not available for
reaping until some time later (after usbdev_remove() has been called).
This is awkward for libusb or other usbfs clients, although not an
insuperable problem.
At any rate, it's easy to change usbfs so that it returns POLLHUP as
soon as the state becomes USB_STATE_NOTATTACHED but it doesn't return
POLLERR until after the outstanding URBs have completed. That's what
this patch does; it uses the fact that ps->list is always on the
dev->filelist list until usbdev_remove() takes it off, which happens
after all the outstanding URBs have been cancelled.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
usbdev_mmap allocates a buffer. The size of the buffer is determined
by a user. So with this code (no need to be root):
int fd = open("/dev/bus/usb/001/001", O_RDONLY);
mmap(NULL, 0x800000, PROT_READ, MAP_SHARED, fd, 0);
we can see a warning:
WARNING: CPU: 0 PID: 21771 at ../mm/page_alloc.c:3563 __alloc_pages_slowpath+0x1036/0x16e0()
...
Call Trace:
[<ffffffff8117a3ae>] ? warn_slowpath_null+0x2e/0x40
[<ffffffff815178b6>] ? __alloc_pages_slowpath+0x1036/0x16e0
[<ffffffff81516880>] ? warn_alloc_failed+0x250/0x250
[<ffffffff8151226b>] ? get_page_from_freelist+0x75b/0x28b0
[<ffffffff815184e3>] ? __alloc_pages_nodemask+0x583/0x6b0
[<ffffffff81517f60>] ? __alloc_pages_slowpath+0x16e0/0x16e0
[<ffffffff810565d4>] ? dma_generic_alloc_coherent+0x104/0x220
[<ffffffffa0269e56>] ? hcd_buffer_alloc+0x1d6/0x3e0 [usbcore]
[<ffffffffa0269c80>] ? hcd_buffer_destroy+0xa0/0xa0 [usbcore]
[<ffffffffa0228f05>] ? usb_alloc_coherent+0x65/0x90 [usbcore]
[<ffffffffa0275c05>] ? usbdev_mmap+0x1a5/0x770 [usbcore]
...
Allocations like this one should be marked as __GFP_NOWARN. So do so.
The size could be also clipped by something like:
if (size >= (1 << (MAX_ORDER + PAGE_SHIFT - 1)))
return -ENOMEM;
But I think the overall limit of 16M (by usbfs_increase_memory_usage)
is enough, so that we only silence the warning here.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Steinar H. Gunderson <sesse@google.com>
Cc: Markus Rechberger <mrechberger@gmail.com>
Fixes: f7d34b445a (USB: Add support for usbfs zerocopy.)
Cc: 4.6+ <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In ehci_turn_off_all_ports() all EHCI port registers are cleared to zero.
On some hardware, this can lead to an system hang,
when ehci_port_power() accesses the already cleared registers.
This patch changes the order of cleanup.
First call ehci_port_power() which respects the current bits in
port status registers
and afterwards cleanup the hard way by setting everything to zero.
Signed-off-by: Marc Ohlf <ohlf@mkt-sys.de>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Erroneous or malicious endpoint descriptors may have non-zero bits in
reserved positions, or out-of-bounds values. This patch helps prevent
these from causing problems by bounds-checking the wMaxPacketValue
entries in endpoint descriptors and capping the values at the maximum
allowed.
This issue was first discovered and tests were conducted by Jake Lamberson
<jake.lamberson1@gmail.com>, an intern working for Rosie Hall.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: roswest <roswest@cisco.com>
Tested-by: roswest <roswest@cisco.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Let's follow other driver registration functions and
automatically set the driver's owner member to THIS_MODULE when
ulpi_driver_register() is called. This allows ulpi driver writers
to forget about this boiler plate detail and avoids common bugs
in the process.
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It's a rather simple controller, we just need to make sure USB is
powered (using GPIO pin) and reset bus core. Once this is done it's
safe to register XHCI controller and let it init PHY and do its magic.
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since commit 71723f9546 "PM / runtime: print error when activating a
child to unactive parent" I see the following error message:
scsi host2: usb-storage 1-3:1.0
scsi host2: runtime PM trying to activate child device host2 but parent
(1-3:1.0) is not active
Digging into it it seems to be related to the problem described in the
commit message for cd998ded5c "i2c: designware: Prevent runtime
suspend during adapter registration" as scsi_add_host also calls
device_add and after the call to device_add the parent device is
suspended.
Fix this by using the approach from the mentioned commit and getting
the runtime pm reference before calling scsi_add_host.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The driver enforces a strict one-to-one relationship between the
received RESPONSE_AVAILABLE notifications and messages read from
the device. At the same time, it will cancel the interrupt URB
when there is no client holding the character device open.
Many devices do not cope well with this behaviour. They maintain
a FIFO queue of messages, and send notifications on a best effort
basis. Messages are queued regardless of whether the notification
is successful or not. So if the driver loses a single notification,
which can easily happen when the interrupt URB is cancelled, then
the device and driver becomes out-of-sync. New messages end up
at the end of the queue, while the associated notification makes
the driver read only the first message from the queue.
This state is permanent from a user point of view. There is no
no way to flush the device queue without resetting the device or
using another driver.
The problem is easy to hit with current QMI and MBIM command line
tools, which typically close the character device after seeing
the reply they expect. Any pending unsolicited messages from the
device will then trigger the driver bug.
Fix by always reading all queued messages from the device when
the notification URB is first submitted. This is expected to
end with an -EPIPE status when there are no more pending
messages, so demote the printk associated with -EPIPE to debug
level.
The workaround has been tested on a large number of different MBIM
and QMI devices, as well as the Ericsson F5521gw and H5321gw modems
with real Device Management functions.
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
alloc_ordered_workqueue replaces the deprecated
create_singlethread_workqueue.
There are multiple work items on the work queue, which require
ordering. Hence, an ordered workqueue has been used.
The workqueue "wq_otg" is not being used on a memory reclaim path.
Hence, WQ_MEM_RECLAIM has not been set.
Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The status workqueue is involved in initializing the Uxxx and polling
the Uxxx until a supported PCMCIA CardBus device is detected.
It then starts the command and respond workqueues and then loads the
module that handles the device, after which it just polls the Uxxx
looking for card ejects.
The command and respond workqueues are involved in implementing a command
sequencer for communicating with the firmware on the other side of
the FTDI chip in the Uxxx.
These workqueues have only a single work item each and hence they do not
require ordering. Also, none of the above workqueues are being used on a
memory recliam path. Hence, the singlethreaded workqueues have been
replaced with the use of system_wq.
System workqueues have been able to handle high level of concurrency
for a long time now and hence it's not required to have a singlethreaded
workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue
created with create_singlethread_workqueue(), system_wq allows multiple
work items to overlap executions even on the same CPU; however, a
per-cpu workqueue doesn't have any CPU locality or global ordering
guarantee unless the target CPU is explicitly specified and thus the
increase of local concurrency shouldn't make any difference.
The work items have been sync cancelled because they are self-requeueing
and need to wait for the in-flight work item to finish before proceeding
with destruction. Hence, they have been sync cancelled in
ftdi_status_cancel_work(), ftdi_command_cancel_work() and
ftdi_response_cancel_work(). These functions are called in
ftdi_elan_exit() to ensure that there are no pending work items while
disconnecting the driver.
Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The workqueue "wq" is involved in controlling the brightness of an
Apple Cinema Display over USB.
It has a single work item(&pdata->work) per appledisplay and hence
doesn't require ordering. Also, it is not being used on a memory
reclaim path.
Hence, the singlethreaded workqueue has been replaced with the use of
system_wq.
System workqueues have been able to handle high level of concurrency
for a long time now and hence it's not required to have a singlethreaded
workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue
created with create_singlethread_workqueue(), system_wq allows multiple
work items to overlap executions even on the same CPU; however, a
per-cpu workqueue doesn't have any CPU locality or global ordering
guarantee unless the target CPU is explicitly specified and thus the
increase of local concurrency shouldn't make any difference.
The work item is self-requeueing and needs to wait for the in-flight
work item to finish before proceeding with destruction.
Hence, it has been sync cancelled in appledisplay_disconnect().
This also ensures that there are no pending tasks while disconnecting
the driver.
Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
