Messages in this thread Patch in this message | | | Date | Wed, 28 Mar 2007 08:22:01 +0200 | From | Eric Dumazet <> | Subject | [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 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> --- linux-2.6.21-rc5-mm1/arch/x86_64/kernel/vsyscall.c +++ linux-2.6.21-rc5-mm1-ed/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 (!__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. | |