2009-04-23 07:46:42

by Chris Wright

Subject: [patch 058/100] posix-timers: fix RLIMIT_CPU && setitimer(CPUCLOCK_PROF)

-stable review patch. If anyone has any objections, please let us know.
---------------------

From: Oleg Nesterov <[email protected]>

upstream commit: 8f2e586567b1bad72dac7c3810fe9a2ef7117506

update_rlimit_cpu() tries to optimize out set_process_cpu_timer() in case
when we already have CPUCLOCK_PROF timer which should expire first. But it
uses cputime_lt() instead of cputime_gt().

Test case:

int main(void)
{
struct itimerval it = {
.it_value = { .tv_sec = 1000 },
};

assert(!setitimer(ITIMER_PROF, &it, NULL));

struct rlimit rl = {
.rlim_cur = 1,
.rlim_max = 1,
};

assert(!setrlimit(RLIMIT_CPU, &rl));

for (;;)
;

return 0;
}

Without this patch, the task is not killed as RLIMIT_CPU demands.

Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Peter Lojkin <[email protected]>
Cc: Roland McGrath <[email protected]>
Cc: [email protected]
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Chris Wright <[email protected]>
---
kernel/posix-cpu-timers.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -18,7 +18,7 @@ void update_rlimit_cpu(unsigned long rli

cputime = secs_to_cputime(rlim_new);
if (cputime_eq(current->signal->it_prof_expires, cputime_zero) ||
- cputime_lt(current->signal->it_prof_expires, cputime)) {
+ cputime_gt(current->signal->it_prof_expires, cputime)) {
spin_lock_irq(&current->sighand->siglock);
set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
spin_unlock_irq(&current->sighand->siglock);