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[PATCH] x86-64: fix vtime() vsyscall

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There is a tiny probability that the return value from vtime(time_t *t) is
Signed-off-by: Andi Kleen <ak@suse.de>

different than 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@cosmosbay.com>
This commit is contained in:
Eric Dumazet 2007-05-02 19:27:11 +02:00 committed by Andi Kleen
parent bd8559c38e
commit 272a3713bb
1 changed files with 5 additions and 3 deletions
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8
arch/x86_64/kernel/vsyscall.c
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@ -156,11 +156,13 @@ int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
* 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.