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Subject[patch 17/22] RLIMIT_CPU: fix handling of a zero limit
-stable review patch.  If anyone has any objections, please let us know.

------------------

At present the kernel doesn't honour an attempt to set RLIMIT_CPU to zero
seconds. But the spec says it should, and that's what 2.4.x does.

Fixing this for real would involve some complexity (such as adding a new
it-has-been-set flag to the task_struct, and testing that everwhere, instead
of overloading the value of it_prof_expires).

Given that a 2.4 kernel won't actually send the signal until one second has
expired anyway, let's just handle this case by treating the caller's
zero-seconds as one second.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ulrich Weigand <uweigand@de.ibm.com>
Cc: Cliff Wickman <cpw@sgi.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

---

kernel/sys.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

e0661111e5441995f7a69dc4336c9f131cb9bc58
--- linux-2.6.16.5.orig/kernel/sys.c
+++ linux-2.6.16.5/kernel/sys.c
@@ -1657,7 +1657,19 @@ asmlinkage long sys_setrlimit(unsigned i
(cputime_eq(current->signal->it_prof_expires, cputime_zero) ||
new_rlim.rlim_cur <= cputime_to_secs(
current->signal->it_prof_expires))) {
- cputime_t cputime = secs_to_cputime(new_rlim.rlim_cur);
+ unsigned long rlim_cur = new_rlim.rlim_cur;
+ cputime_t cputime;
+
+ if (rlim_cur == 0) {
+ /*
+ * The caller is asking for an immediate RLIMIT_CPU
+ * expiry. But we use the zero value to mean "it was
+ * never set". So let's cheat and make it one second
+ * instead
+ */
+ rlim_cur = 1;
+ }
+ cputime = secs_to_cputime(rlim_cur);
read_lock(&tasklist_lock);
spin_lock_irq(&current->sighand->siglock);
set_process_cpu_timer(current, CPUCLOCK_PROF,
--
-
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