Commit eaad4513 authored Jan 16, 2014 by Peter Zijlstra Committed by Ingo Molnar Jan 16, 2014

sched: Fix __sched_setscheduler() nice test



With the introduction of sched_attr::sched_nice we need to check
if we've got permission to actually change the nice value.

Daniel found that can_nice() would always fail; and upon
inspection it turns out that can_nice() only tests to see if we
can lower the nice value, but it doesn't validate if we're
lowering or not.

Therefore amend the test to only call can_nice() when we lower
the nice value.

Reported-and-Tested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: raistlin@linux.it
Cc: juri.lelli@gmail.com
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Fixes: d50dde5a ("sched: Add new scheduler syscalls to support an extended scheduling parameters ABI")
Link: http://lkml.kernel.org/r/20140116165425.GA9481@laptop.programming.kicks-ass.net


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 7479f3c9

kernel/sched/core.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -3296,7 +3296,8 @@ static int __sched_setscheduler(struct task_struct *p,
		*/
		if (user && !capable(CAP_SYS_NICE)) {
		if (fair_policy(policy)) {
		if (!can_nice(p, attr->sched_nice))
		if (attr->sched_nice < TASK_NICE(p) &&
		!can_nice(p, attr->sched_nice))
		return -EPERM;
		}