[patch 057/100] posix-timers: fix RLIMIT_CPU && fork()

Chris Wright
2009-04-23T07:47:42Z

[-- Attachment #1: posix-timers-fix-rlimit_cpu-fork.patch --]
[-- Type: text/plain, Size: 2176 bytes --]

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

From: Oleg Nesterov <oleg@redhat.com>

upstream commit: 6279a751fe096a21dc7704e918d570d3ff06e769

See http://bugzilla.kernel.org/show_bug.cgi?id=12911

copy_signal() copies signal->rlim, but RLIMIT_CPU is "lost". Because
posix_cpu_timers_init_group() sets cputime_expires.prof_exp = 0 and thus
fastpath_timer_check() returns false unless we have other expired cpu timers.

Change copy_signal() to set cputime_expires.prof_exp if we have RLIMIT_CPU.
Also, set cputimer.running = 1 in that case. This is not strictly necessary,
but imho makes sense.

Reported-by: Peter Lojkin <ia6432@inbox.ru>
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: <20090327000607.GA10104@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
kernel/fork.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -808,6 +808,12 @@ static void posix_cpu_timers_init_group(
sig->cputime_expires.virt_exp = cputime_zero;
sig->cputime_expires.sched_exp = 0;

+ if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
+ sig->cputime_expires.prof_exp =
+ secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
+ sig->cputimer.running = 1;
+ }
+
/* The timer lists. */
INIT_LIST_HEAD(&sig->cpu_timers[0]);
INIT_LIST_HEAD(&sig->cpu_timers[1]);
@@ -823,11 +829,8 @@ static int copy_signal(unsigned long clo
atomic_inc(&current->signal->live);
return 0;
}
- sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
-
- if (sig)
- posix_cpu_timers_init_group(sig);

+ sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
tsk->signal = sig;
if (!sig)
return -ENOMEM;
@@ -865,6 +868,8 @@ static int copy_signal(unsigned long clo
memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
task_unlock(current->group_leader);

+ posix_cpu_timers_init_group(sig);
+
acct_init_pacct(&sig->pacct);

tty_audit_fork(sig);