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sched: Protect task->cpus_allowed access in sched_getaffinity()

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sched_getaffinity() is not protected against a concurrent
modification of the tasks affinity.

Serialize the access with task_rq_lock(task).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091208202026.769251187@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Thomas Gleixner
2009-12-08 20:24:16 +00:00
committed by Ingo Molnar
parent 6ad4c18884
commit 3160568371
1 changed files with 4 additions and 0 deletions
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4
kernel/sched.c
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@@ -6631,6 +6631,8 @@ SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
long sched_getaffinity(pid_t pid, struct cpumask *mask) long sched_getaffinity(pid_t pid, struct cpumask *mask)
{ {
struct task_struct *p; struct task_struct *p;
unsigned long flags;
struct rq *rq;
int retval; int retval;
get_online_cpus(); get_online_cpus();
@@ -6645,7 +6647,9 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask)
if (retval) if (retval)
goto out_unlock; goto out_unlock;
rq = task_rq_lock(p, &flags);
cpumask_and(mask, &p->cpus_allowed, cpu_online_mask); cpumask_and(mask, &p->cpus_allowed, cpu_online_mask);
task_rq_unlock(rq, &flags);
out_unlock: out_unlock:
read_unlock(&tasklist_lock); read_unlock(&tasklist_lock);