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author | Thomas Gleixner <tglx@linutronix.de> | 2012-02-28 19:46:04 +0000 |
---|---|---|
committer | John Stultz <john.stultz@linaro.org> | 2012-03-15 18:17:58 -0700 |
commit | 2ab516575f2f273b19d95140d02c54612201e80a (patch) | |
tree | 26db92249e65754d99759af21fd207507a81cec8 | |
parent | 6c260d586343f7f78239d90aa9e2cfed02f74ff3 (diff) | |
download | linux-3.10-2ab516575f2f273b19d95140d02c54612201e80a.tar.gz linux-3.10-2ab516575f2f273b19d95140d02c54612201e80a.tar.bz2 linux-3.10-2ab516575f2f273b19d95140d02c54612201e80a.zip |
x86: vdso: Use seqcount instead of seqlock
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>
-rw-r--r-- | arch/x86/include/asm/vgtod.h | 2 | ||||
-rw-r--r-- | arch/x86/kernel/vsyscall_64.c | 11 | ||||
-rw-r--r-- | arch/x86/vdso/vclock_gettime.c | 16 |
3 files changed, 12 insertions, 17 deletions
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h index 815285bcace..1f007178c81 100644 --- a/arch/x86/include/asm/vgtod.h +++ b/arch/x86/include/asm/vgtod.h @@ -5,7 +5,7 @@ #include <linux/clocksource.h> struct vsyscall_gtod_data { - seqlock_t lock; + seqcount_t seq; /* open coded 'struct timespec' */ time_t wall_time_sec; diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c index 33385c18e5d..cdc95a707cd 100644 --- a/arch/x86/kernel/vsyscall_64.c +++ b/arch/x86/kernel/vsyscall_64.c @@ -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, diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c index 7eeb1f6188e..944c5e5d6b6 100644 --- a/arch/x86/vdso/vclock_gettime.c +++ b/arch/x86/vdso/vclock_gettime.c @@ -100,12 +100,12 @@ notrace static noinline int do_realtime(struct timespec *ts) int mode; do { - seq = read_seqbegin(>od->lock); + seq = read_seqcount_begin(>od->seq); mode = gtod->clock.vclock_mode; ts->tv_sec = gtod->wall_time_sec; ts->tv_nsec = gtod->wall_time_nsec; ns = vgetns(); - } while (unlikely(read_seqretry(>od->lock, seq))); + } while (unlikely(read_seqcount_retry(>od->seq, seq))); timespec_add_ns(ts, ns); return mode; @@ -117,13 +117,13 @@ notrace static noinline int do_monotonic(struct timespec *ts) int mode; do { - seq = read_seqbegin(>od->lock); + seq = read_seqcount_begin(>od->seq); mode = gtod->clock.vclock_mode; secs = gtod->wall_time_sec; ns = gtod->wall_time_nsec + vgetns(); secs += gtod->wall_to_monotonic.tv_sec; ns += gtod->wall_to_monotonic.tv_nsec; - } while (unlikely(read_seqretry(>od->lock, seq))); + } while (unlikely(read_seqcount_retry(>od->seq, seq))); /* wall_time_nsec, vgetns(), and wall_to_monotonic.tv_nsec * are all guaranteed to be nonnegative. @@ -142,10 +142,10 @@ notrace static noinline int do_realtime_coarse(struct timespec *ts) { unsigned long seq; do { - seq = read_seqbegin(>od->lock); + seq = read_seqcount_begin(>od->seq); ts->tv_sec = gtod->wall_time_coarse.tv_sec; ts->tv_nsec = gtod->wall_time_coarse.tv_nsec; - } while (unlikely(read_seqretry(>od->lock, seq))); + } while (unlikely(read_seqcount_retry(>od->seq, seq))); return 0; } @@ -153,12 +153,12 @@ notrace static noinline int do_monotonic_coarse(struct timespec *ts) { unsigned long seq, ns, secs; do { - seq = read_seqbegin(>od->lock); + seq = read_seqcount_begin(>od->seq); secs = gtod->wall_time_coarse.tv_sec; ns = gtod->wall_time_coarse.tv_nsec; secs += gtod->wall_to_monotonic.tv_sec; ns += gtod->wall_to_monotonic.tv_nsec; - } while (unlikely(read_seqretry(>od->lock, seq))); + } while (unlikely(read_seqcount_retry(>od->seq, seq))); /* wall_time_nsec and wall_to_monotonic.tv_nsec are * guaranteed to be between 0 and NSEC_PER_SEC. |