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sched: More sched_domain iterations fixes 

sched_domain iterations needs to be protected by rcu_read_lock() now,
this patch adds another two places which needs the rcu lock, which is
spotted by following suspicious rcu_dereference_check() usage warnings.

kernel/sched_rt.c:1244 invoked rcu_dereference_check() without protection!
kernel/sched_stats.h:41 invoked rcu_dereference_check() without protection!

Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1303469634-11678-1-git-send-email-dfeng@redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Xiaotian Feng 2011-04-22 18:53:54 +08:00 committed by Ingo Molnar
parent dc7acbb251
commit cd4ae6adf8
2 changed files with 10 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
kernel/sched_rt.c
View File

@ -1263,6 +1263,7 @@ static int find_lowest_rq(struct task_struct *task)
if (!cpumask_test_cpu(this_cpu, lowest_mask)) if (!cpumask_test_cpu(this_cpu, lowest_mask))
this_cpu = -1; /* Skip this_cpu opt if not among lowest */ this_cpu = -1; /* Skip this_cpu opt if not among lowest */
rcu_read_lock();
for_each_domain(cpu, sd) { for_each_domain(cpu, sd) {
if (sd->flags & SD_WAKE_AFFINE) { if (sd->flags & SD_WAKE_AFFINE) {
int best_cpu; int best_cpu;
@ -1272,15 +1273,20 @@ static int find_lowest_rq(struct task_struct *task)
* remote processor. * remote processor.
*/ */
if (this_cpu != -1 && if (this_cpu != -1 &&
cpumask_test_cpu(this_cpu, sched_domain_span(sd))) cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
rcu_read_unlock();
return this_cpu; return this_cpu;
}
best_cpu = cpumask_first_and(lowest_mask, best_cpu = cpumask_first_and(lowest_mask,
sched_domain_span(sd)); sched_domain_span(sd));
if (best_cpu < nr_cpu_ids) if (best_cpu < nr_cpu_ids) {
rcu_read_unlock();
return best_cpu; return best_cpu;
}
} }
} }
rcu_read_unlock();
/* /*
* And finally, if there were no matches within the domains * And finally, if there were no matches within the domains

4
kernel/sched_stats.h
View File

@ -37,7 +37,7 @@ static int show_schedstat(struct seq_file *seq, void *v)
#ifdef CONFIG_SMP #ifdef CONFIG_SMP
/* domain-specific stats */ /* domain-specific stats */
preempt_disable(); rcu_read_lock();
for_each_domain(cpu, sd) { for_each_domain(cpu, sd) {
enum cpu_idle_type itype; enum cpu_idle_type itype;
@ -64,7 +64,7 @@ static int show_schedstat(struct seq_file *seq, void *v)
sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_wake_remote, sd->ttwu_move_affine,
sd->ttwu_move_balance); sd->ttwu_move_balance);
} }
preempt_enable(); rcu_read_unlock();
#endif #endif
} }
kfree(mask_str); kfree(mask_str);