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

Chris Wright
2009-04-23T07:46:42Z

[-- Attachment #1: posix-timers-fix-rlimit_cpu-setitimer.patch --]
[-- Type: text/plain, Size: 1681 bytes --]

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

From: Oleg Nesterov <oleg@redhat.com>

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 <oleg@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Peter Lojkin <ia6432@inbox.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: stable@kernel.org
LKML-Reference: <20090327000610.GA10108@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
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);