From: Thomas Gleixner 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. Signed-off-by: Thomas Gleixner Cc: stable-rt@vger.kernel.org Signed-off-by: Steven Rostedt --- arch/x86/include/asm/vgtod.h | 2 +- arch/x86/kernel/vsyscall_64.c | 11 +++-------- 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 646b4c1..10e09fc 100644 --- a/arch/x86/include/asm/vgtod.h +++ b/arch/x86/include/asm/vgtod.h @@ -5,7 +5,7 @@ #include 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 c378a18..c1fe684 100644 --- a/arch/x86/kernel/vsyscall_64.c +++ b/arch/x86/kernel/vsyscall_64.c @@ -50,11 +50,7 @@ #include DEFINE_VVAR(int, vgetcpu_mode); -DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) = -{ - .lock = __SEQLOCK_UNLOCKED(__vsyscall_gtod_data.lock), - .sysctl_enabled = 1, -}; +DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data); void update_vsyscall_tz(void) { @@ -64,9 +60,8 @@ void update_vsyscall_tz(void) void update_vsyscall(struct timespec *wall_time, struct timespec *wtm, struct clocksource *clock, u32 mult) { - unsigned long flags; + write_seqcount_begin(&vsyscall_gtod_data.seq); - write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags); /* copy vsyscall data */ vsyscall_gtod_data.clock.vread = clock->vread; @@ -79,7 +74,7 @@ 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 a724905..117e6cf 100644 --- a/arch/x86/vdso/vclock_gettime.c +++ b/arch/x86/vdso/vclock_gettime.c @@ -46,11 +46,11 @@ notrace static noinline int do_realtime(struct timespec *ts) { unsigned long seq, ns; do { - seq = read_seqbegin(>od->lock); + seq = read_seqcount_begin(>od->seq); 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 0; } @@ -59,12 +59,12 @@ notrace static noinline int do_monotonic(struct timespec *ts) { unsigned long seq, ns, secs; do { - seq = read_seqbegin(>od->lock); + seq = read_seqcount_begin(>od->seq); 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. @@ -83,10 +83,10 @@ 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; } @@ -94,12 +94,12 @@ 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. -- 1.7.8.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/