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authorThomas Gleixner <tglx@linutronix.de>2009-12-09 10:15:01 +0000
committerIngo Molnar <mingo@elte.hu>2009-12-14 17:11:35 +0100
commit23f5d142519621b16cf2b378cf8adf4dcf01a616 (patch)
treec7907cb635ea1ad6cab71598d687b752c17adf37 /kernel
parent5fe85be081edf0ac92d83f9c39e0ab5c1371eb82 (diff)
sched: Use rcu in sched_get/set_affinity()
tasklist_lock is held read locked to protect the find_task_by_vpid() call and to prevent the task going away. sched_setaffinity acquires a task struct ref and drops tasklist lock right away. The access to the cpus_allowed mask is protected by rq->lock. rcu_read_lock() provides the same protection here. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <20091209100706.789059966@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c16
1 files changed, 6 insertions, 10 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 1782beed2fa..79893123325 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6516,22 +6516,18 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
int retval;
get_online_cpus();
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_process_by_pid(pid);
if (!p) {
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
put_online_cpus();
return -ESRCH;
}
- /*
- * It is not safe to call set_cpus_allowed with the
- * tasklist_lock held. We will bump the task_struct's
- * usage count and then drop tasklist_lock.
- */
+ /* Prevent p going away */
get_task_struct(p);
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
retval = -ENOMEM;
@@ -6617,7 +6613,7 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask)
int retval;
get_online_cpus();
- read_lock(&tasklist_lock);
+ rcu_read_lock();
retval = -ESRCH;
p = find_process_by_pid(pid);
@@ -6633,7 +6629,7 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask)
task_rq_unlock(rq, &flags);
out_unlock:
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
put_online_cpus();
return retval;