2013-02-26 04:06:06 +00:00
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From a58bf9f435b1f3232a9352c901d3fcec4ef9aaec Mon Sep 17 00:00:00 2001
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2012-03-04 13:31:34 +00:00
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Tue, 28 Feb 2012 18:24:07 +0100
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2013-02-26 04:06:06 +00:00
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Subject: [PATCH 018/304] x86: vdso: Use seqcount instead of seqlock
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2012-03-04 13:31:34 +00:00
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The update of the vdso data happens under xtime_lock, so adding a
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nested lock is pointless. Just use a seqcount to sync the readers.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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arch/x86/include/asm/vgtod.h | 2 +-
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arch/x86/kernel/vsyscall_64.c | 11 +++--------
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arch/x86/vdso/vclock_gettime.c | 16 ++++++++--------
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3 files changed, 12 insertions(+), 17 deletions(-)
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2012-05-12 14:20:55 +00:00
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diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
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index 815285b..1f00717 100644
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--- a/arch/x86/include/asm/vgtod.h
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+++ b/arch/x86/include/asm/vgtod.h
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2012-03-04 13:31:34 +00:00
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@@ -5,7 +5,7 @@
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#include <linux/clocksource.h>
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struct vsyscall_gtod_data {
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- seqlock_t lock;
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+ seqcount_t seq;
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/* open coded 'struct timespec' */
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time_t wall_time_sec;
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2012-05-12 14:20:55 +00:00
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diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
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index f04adbd..50392ee 100644
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--- a/arch/x86/kernel/vsyscall_64.c
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+++ b/arch/x86/kernel/vsyscall_64.c
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2012-03-04 13:31:34 +00:00
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@@ -52,10 +52,7 @@
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#include "vsyscall_trace.h"
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DEFINE_VVAR(int, vgetcpu_mode);
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-DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) =
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-{
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- .lock = __SEQLOCK_UNLOCKED(__vsyscall_gtod_data.lock),
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-};
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+DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data);
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static enum { EMULATE, NATIVE, NONE } vsyscall_mode = NATIVE;
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@@ -86,9 +83,7 @@ void update_vsyscall_tz(void)
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void update_vsyscall(struct timespec *wall_time, struct timespec *wtm,
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struct clocksource *clock, u32 mult)
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{
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- unsigned long flags;
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-
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- write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags);
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+ write_seqcount_begin(&vsyscall_gtod_data.seq);
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/* copy vsyscall data */
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vsyscall_gtod_data.clock.vclock_mode = clock->archdata.vclock_mode;
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2012-05-12 14:20:55 +00:00
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@@ -101,7 +96,7 @@ void update_vsyscall(struct timespec *wall_time, struct timespec *wtm,
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2012-03-04 13:31:34 +00:00
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vsyscall_gtod_data.wall_to_monotonic = *wtm;
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vsyscall_gtod_data.wall_time_coarse = __current_kernel_time();
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- write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags);
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+ write_seqcount_end(&vsyscall_gtod_data.seq);
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}
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static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,
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2012-05-12 14:20:55 +00:00
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diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
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index 6bc0e72..d8511fb 100644
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--- a/arch/x86/vdso/vclock_gettime.c
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+++ b/arch/x86/vdso/vclock_gettime.c
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@@ -86,11 +86,11 @@ notrace static noinline int do_realtime(struct timespec *ts)
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2012-03-04 13:31:34 +00:00
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{
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unsigned long seq, ns;
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do {
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- seq = read_seqbegin(>od->lock);
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+ seq = read_seqcount_begin(>od->seq);
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ts->tv_sec = gtod->wall_time_sec;
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ts->tv_nsec = gtod->wall_time_nsec;
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ns = vgetns();
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- } while (unlikely(read_seqretry(>od->lock, seq)));
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+ } while (unlikely(read_seqcount_retry(>od->seq, seq)));
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timespec_add_ns(ts, ns);
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return 0;
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}
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2012-05-12 14:20:55 +00:00
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@@ -99,12 +99,12 @@ notrace static noinline int do_monotonic(struct timespec *ts)
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2012-03-04 13:31:34 +00:00
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{
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unsigned long seq, ns, secs;
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do {
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- seq = read_seqbegin(>od->lock);
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+ seq = read_seqcount_begin(>od->seq);
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secs = gtod->wall_time_sec;
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ns = gtod->wall_time_nsec + vgetns();
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secs += gtod->wall_to_monotonic.tv_sec;
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ns += gtod->wall_to_monotonic.tv_nsec;
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- } while (unlikely(read_seqretry(>od->lock, seq)));
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+ } while (unlikely(read_seqcount_retry(>od->seq, seq)));
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/* wall_time_nsec, vgetns(), and wall_to_monotonic.tv_nsec
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* are all guaranteed to be nonnegative.
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2012-05-12 14:20:55 +00:00
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@@ -123,10 +123,10 @@ notrace static noinline int do_realtime_coarse(struct timespec *ts)
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2012-03-04 13:31:34 +00:00
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{
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unsigned long seq;
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do {
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- seq = read_seqbegin(>od->lock);
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+ seq = read_seqcount_begin(>od->seq);
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ts->tv_sec = gtod->wall_time_coarse.tv_sec;
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ts->tv_nsec = gtod->wall_time_coarse.tv_nsec;
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- } while (unlikely(read_seqretry(>od->lock, seq)));
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+ } while (unlikely(read_seqcount_retry(>od->seq, seq)));
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return 0;
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}
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2012-05-12 14:20:55 +00:00
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@@ -134,12 +134,12 @@ notrace static noinline int do_monotonic_coarse(struct timespec *ts)
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2012-03-04 13:31:34 +00:00
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{
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unsigned long seq, ns, secs;
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do {
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- seq = read_seqbegin(>od->lock);
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+ seq = read_seqcount_begin(>od->seq);
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secs = gtod->wall_time_coarse.tv_sec;
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ns = gtod->wall_time_coarse.tv_nsec;
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secs += gtod->wall_to_monotonic.tv_sec;
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ns += gtod->wall_to_monotonic.tv_nsec;
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- } while (unlikely(read_seqretry(>od->lock, seq)));
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+ } while (unlikely(read_seqcount_retry(>od->seq, seq)));
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/* wall_time_nsec and wall_to_monotonic.tv_nsec are
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* guaranteed to be between 0 and NSEC_PER_SEC.
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