The patch titled
x86_64: fix vtime() vsyscall
has been added to the -mm tree. Its filename is
x86_64-fix-vtime-vsyscall.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: x86_64: fix vtime() vsyscall
From: Eric Dumazet <dada1@xxxxxxxxxxxxx>
There is a tiny probability that the return value from vtime(time_t *t) is
different from the value stored in *t.
Using a temporary variable solves the problem and gives a faster code.
17: 48 85 ff test %rdi,%rdi
1a: 48 8b 05 00 00 00 00 mov 0(%rip),%rax #
__vsyscall_gtod_data.wall_time_tv.tv_sec
21: 74 03 je 26
23: 48 89 07 mov %rax,(%rdi)
26: c9 leaveq
27: c3 retq
Signed-off-by: Eric Dumazet <dada1@xxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86_64/kernel/vsyscall.c | 10 +++++-----
1 files changed, 5 insertions(+), 5 deletions(-)
diff -puN arch/x86_64/kernel/vsyscall.c~x86_64-fix-vtime-vsyscall arch/x86_64/kernel/vsyscall.c
--- a/arch/x86_64/kernel/vsyscall.c~x86_64-fix-vtime-vsyscall
+++ a/arch/x86_64/kernel/vsyscall.c
@@ -147,15 +147,15 @@ int __vsyscall(0) vgettimeofday(struct t
return 0;
}
-/* This will break when the xtime seconds get inaccurate, but that is
- * unlikely */
time_t __vsyscall(1) vtime(time_t *t)
{
+ time_t result;
if (unlikely(!__vsyscall_gtod_data.sysctl_enabled))
return time_syscall(t);
- else if (t)
- *t = __vsyscall_gtod_data.wall_time_tv.tv_sec;
- return __vsyscall_gtod_data.wall_time_tv.tv_sec;
+ result = __vsyscall_gtod_data.wall_time_tv.tv_sec;
+ if (t)
+ *t = result;
+ return result;
}
/* Fast way to get current CPU and node.
_
Patches currently in -mm which might be from dada1@xxxxxxxxxxxxx are
x86_64-move-__vgetcpu_mode-__jiffies-to-the-vsyscall_2-zone.patch
x86_64-fix-vtime-vsyscall.patch
slab-use-num_possible_cpus-in-enable_cpucache.patch
slab-dont-allocate-empty-shared-caches.patch
slab-numa-kmem_cache-diet.patch
optimize-timespec_trunc.patch
procfs-reorder-struct-pid_dentry-to-save-space-on-64bit-archs-and-constify-them.patch
vfs-delay-the-dentry-name-generation-on-sockets-and.patch
getrusage-fill-ru_inblock-and-ru_oublock-fields-if-possible.patch
time-smp-friendly-alignment-of-struct-clocksource.patch
make-static-counters-in-new_inode-and-iunique-be-32-bits.patch
speedup-divides-by-cpu_power-in-scheduler.patch
-
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