* sys_gettimeofday racy or not?
@ 2004-06-25 0:20 Wichert Akkerman
2004-06-25 4:53 ` Chris Friesen
0 siblings, 1 reply; 2+ messages in thread
From: Wichert Akkerman @ 2004-06-25 0:20 UTC (permalink / raw)
To: linux-kernel
This just happened to catch my eye and it's probably perfectly
valid, but if so please educate me on why it is. In kernel/time.c
sys_gettimeofday() there is this code:
if (unlikely(tz != NULL)) {
if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
return -EFAULT;
}
what prevents sys_tz from being changed while this code runs?
Wichert.
--
Wichert Akkerman <wichert@wiggy.net> It is simple to make things.
http://www.wiggy.net/ It is hard to make things simple.
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: sys_gettimeofday racy or not?
2004-06-25 0:20 sys_gettimeofday racy or not? Wichert Akkerman
@ 2004-06-25 4:53 ` Chris Friesen
0 siblings, 0 replies; 2+ messages in thread
From: Chris Friesen @ 2004-06-25 4:53 UTC (permalink / raw)
To: Wichert Akkerman; +Cc: linux-kernel
Wichert Akkerman wrote:
> This just happened to catch my eye and it's probably perfectly
> valid, but if so please educate me on why it is. In kernel/time.c
> sys_gettimeofday() there is this code:
>
> if (unlikely(tz != NULL)) {
> if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
> return -EFAULT;
> }
>
> what prevents sys_tz from being changed while this code runs?
Nothing at all.
I suspect most people don't worry about it, since its use is deprecated. The
man page for gettimeofday() says "The use of the timezone struct is obsolete".
Chris
^ permalink raw reply [flat|nested] 2+ messages in thread
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