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Subject[tip:timers/urgent] posix-timers: fix RLIMIT_CPU && setitimer(CPUCLOCK_PROF)
Commit-ID:  8f2e586567b1bad72dac7c3810fe9a2ef7117506
Gitweb: http://git.kernel.org/tip/8f2e586567b1bad72dac7c3810fe9a2ef7117506
Author: Oleg Nesterov <oleg@redhat.com>
AuthorDate: Fri, 27 Mar 2009 01:06:10 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 8 Apr 2009 17:51:39 +0200

posix-timers: fix RLIMIT_CPU && setitimer(CPUCLOCK_PROF)

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>


---
kernel/posix-cpu-timers.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 8e5d9a6..bb53185 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -18,7 +18,7 @@ void update_rlimit_cpu(unsigned long rlim_new)

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);

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