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Commit 8bdc3de9 authored by Vikram Mulukutla's avatar Vikram Mulukutla
Browse files

sched: core: Fix possible hotplug race in set_cpus_allowed_ptr 



Since a CPU may go offline after cpu_active_mask is used
to query active CPUs, set_cpus_allowed_ptr might inadverntently
pass an invalid cpu number to move_queued_task.

Fix this by ensuring that the cpumask op that uses cpu_active_mask
checks the return value.

CRs-Fixed: 1029014
Change-Id: Id43a629b40b72cc47773e4027d30953b3a94058d
Signed-off-by: default avatarVikram Mulukutla <markivx@codeaurora.org>
parent cc957303

kernel/sched/core.c

+2 −2
Original line number Diff line number Diff line
@@ -8264,7 +8264,8 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) 
	if (cpumask_equal(&p->cpus_allowed, new_mask))

		goto out;



	if (!cpumask_intersects(new_mask, cpu_active_mask)) {

	dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);

	if (dest_cpu >= nr_cpu_ids) {

		ret = -EINVAL;

		goto out;

	}
@@ -8275,7 +8276,6 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) 
	if (cpumask_test_cpu(task_cpu(p), new_mask))

		goto out;



	dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);

	if (task_running(rq, p) || p->state == TASK_WAKING) {

		struct migration_arg arg = { p, dest_cpu };

		/* Need help from migration thread: drop lock and wait. */