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[PATCH] sys_alarm() unsigned signed conversion fixup

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alarm() calls the kernel with an unsigend int timeout in seconds.  The
value is stored in the tv_sec field of a struct timeval to setup the
itimer.  The tv_sec field of struct timeval is of type long, which causes
the tv_sec value to be negative on 32 bit machines if seconds > INT_MAX.

Before the hrtimer merge (pre 2.6.16) such a negative value was converted
to the maximum jiffies timeout by the timeval_to_jiffies conversion.  It's
not clear whether this was intended or just happened to be done by the
timeval_to_jiffies code.

hrtimers expect a timeval in canonical form and treat a negative timeout as
already expired.  This breaks the legitimate usage of alarm() with a
timeout value > INT_MAX seconds.

For 32 bit machines it is therefor necessary to limit the internal seconds
value to avoid API breakage.  Instead of doing this in all implementations
of sys_alarm the duplicated sys_alarm code is moved into a common function
in itimer.c

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Thomas Gleixner
2006-03-25 03:06:33 -08:00
committed by Linus Torvalds
parent 185ae6d7a3
commit c08b8a4910
6 changed files with 43 additions and 61 deletions
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arch/mips/kernel/sysirix.c
+1 -21
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@@ -645,27 +645,7 @@ static inline void getitimer_real(struct itimerval *value)
asmlinkage unsigned int irix_alarm(unsigned int seconds)
{
struct itimerval it_new, it_old;
unsigned int oldalarm;
if (!seconds) {
getitimer_real(&it_old);
del_timer(&current->real_timer);
} else {
it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
it_new.it_value.tv_sec = seconds;
it_new.it_value.tv_usec = 0;
do_setitimer(ITIMER_REAL, &it_new, &it_old);
}
oldalarm = it_old.it_value.tv_sec;
/*
* ehhh.. We can't return 0 if we have an alarm pending ...
* And we'd better return too much than too little anyway
*/
if (it_old.it_value.tv_usec)
oldalarm++;
return oldalarm;
return alarm_setitimer(seconds);
}
asmlinkage int irix_pause(void)