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author | Thomas Gleixner <tglx@linutronix.de> | 2006-03-25 03:06:33 -0800 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-25 08:22:48 -0800 |
commit | c08b8a49100715b20e6f7c997e992428b5e06078 (patch) | |
tree | 014758fb05908a3d49eeadc77f16dfa7585b12ac /kernel/timer.c | |
parent | 185ae6d7a32721e9062030a9f2d24ed714fa45df (diff) | |
download | op-kernel-dev-c08b8a49100715b20e6f7c997e992428b5e06078.zip op-kernel-dev-c08b8a49100715b20e6f7c997e992428b5e06078.tar.gz |
[PATCH] sys_alarm() unsigned signed conversion fixup
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>
Diffstat (limited to 'kernel/timer.c')
-rw-r--r-- | kernel/timer.c | 14 |
1 files changed, 1 insertions, 13 deletions
diff --git a/kernel/timer.c b/kernel/timer.c index 17d956c..13fa72c 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -956,19 +956,7 @@ void do_timer(struct pt_regs *regs) */ asmlinkage unsigned long sys_alarm(unsigned int seconds) { - struct itimerval it_new, it_old; - unsigned int oldalarm; - - 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 ((!oldalarm && it_old.it_value.tv_usec) || it_old.it_value.tv_usec >= 500000) - oldalarm++; - return oldalarm; + return alarm_setitimer(seconds); } #endif |