[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>
diff --git a/include/linux/time.h b/include/linux/time.h
index d9cdba5..bf0e785 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -101,6 +101,7 @@
struct itimerval;
extern int do_setitimer(int which, struct itimerval *value,
struct itimerval *ovalue);
+extern unsigned int alarm_setitimer(unsigned int seconds);
extern int do_getitimer(int which, struct itimerval *value);
extern void getnstimeofday(struct timespec *tv);