diff options
| author | Srikar Dronamraju <srikar@linux.vnet.ibm.com> | 2013-11-12 17:41:26 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-11-19 17:01:15 +0100 |
| commit | 9abf24d465180f5f2eb26a43545348262f16b771 (patch) | |
| tree | b823e6a604a522d7b0c3a374f6d8b8aab4a8acd5 /kernel | |
| parent | MAINTAINERS: Update file patterns in the lockdep and scheduler entries (diff) | |
| download | linux-9abf24d465180f5f2eb26a43545348262f16b771.tar.xz linux-9abf24d465180f5f2eb26a43545348262f16b771.zip | |
sched: Check sched_domain before computing group power
After commit 863bffc80898 ("sched/fair: Fix group power_orig
computation"), we can dereference rq->sd before it is set.
Fix this by falling back to power_of() in this case and add a comment
explaining things.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
[ Added comment and tweaked patch. ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: mikey@neuling.org
Link: http://lkml.kernel.org/r/20131113151718.GN21461@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e8b652ebe027..fd773ade1a31 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5379,10 +5379,31 @@ void update_group_power(struct sched_domain *sd, int cpu) */ for_each_cpu(cpu, sched_group_cpus(sdg)) { - struct sched_group *sg = cpu_rq(cpu)->sd->groups; + struct sched_group_power *sgp; + struct rq *rq = cpu_rq(cpu); - power_orig += sg->sgp->power_orig; - power += sg->sgp->power; + /* + * build_sched_domains() -> init_sched_groups_power() + * gets here before we've attached the domains to the + * runqueues. + * + * Use power_of(), which is set irrespective of domains + * in update_cpu_power(). + * + * This avoids power/power_orig from being 0 and + * causing divide-by-zero issues on boot. + * + * Runtime updates will correct power_orig. + */ + if (unlikely(!rq->sd)) { + power_orig += power_of(cpu); + power += power_of(cpu); + continue; + } + + sgp = rq->sd->groups->sgp; + power_orig += sgp->power_orig; + power += sgp->power; } } else { /* |