xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

x86: vdso: Use seqcount instead of seqlock

Browse Source 
The update of the vdso data happens under xtime_lock, so adding a
nested lock is pointless. Just use a seqcount to sync the readers.

Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
Thomas Gleixner
2012-02-28 19:46:04 +00:00
committed by John Stultz
parent 6c260d5863
commit 2ab516575f
3 changed files with 12 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
arch/x86/kernel/vsyscall_64.c
View File

@@ -52,10 +52,7 @@
#include "vsyscall_trace.h"
DEFINE_VVAR(int, vgetcpu_mode);
DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) =
{
.lock = __SEQLOCK_UNLOCKED(__vsyscall_gtod_data.lock),
};
DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data);
static enum { EMULATE, NATIVE, NONE } vsyscall_mode = EMULATE;
@@ -86,9 +83,7 @@ void update_vsyscall_tz(void)
void update_vsyscall(struct timespec *wall_time, struct timespec *wtm,
struct clocksource *clock, u32 mult)
{
unsigned long flags;
write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags);
write_seqcount_begin(&vsyscall_gtod_data.seq);
/* copy vsyscall data */
vsyscall_gtod_data.clock.vclock_mode = clock->archdata.vclock_mode;
@@ -101,7 +96,7 @@ void update_vsyscall(struct timespec *wall_time, struct timespec *wtm,
vsyscall_gtod_data.wall_to_monotonic = *wtm;
vsyscall_gtod_data.wall_time_coarse = __current_kernel_time();
write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags);
write_seqcount_end(&vsyscall_gtod_data.seq);
}
static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,