[tip:sched/core] sched: Fix/remove redundant cfs_rq checks

tip-bot for Paul Turner
2011-01-26T12:10:39Z

Commit-ID: b815f1963e47b9b69bb17e0588bd5af5b1114ae0
Gitweb: http://git.kernel.org/tip/b815f1963e47b9b69bb17e0588bd5af5b1114ae0
Author: Paul Turner <pjt@google.com>
AuthorDate: Fri, 21 Jan 2011 20:45:00 -0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 26 Jan 2011 12:31:02 +0100

sched: Fix/remove redundant cfs_rq checks

Since updates are against an entity's queuing cfs_rq it's not possible to
enter update_cfs_{shares,load} with a NULL cfs_rq. (Indeed, update_cfs_load
would crash prior to the check if we did anyway since we load is examined
during the initializers).

Also, in the update_cfs_load case there's no point
in maintaining averages for rq->cfs_rq since we don't perform shares
distribution at that level -- NULL check is replaced accordingly.

Thanks to Dan Carpenter for pointing out the deference before NULL check.

Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20110122044851.825284940@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched_fair.c | 5 +----
1 files changed, 1 insertions(+), 4 deletions(-)

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index ccecfec..1997383 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -722,7 +722,7 @@ static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
u64 now, delta;
unsigned long load = cfs_rq->load.weight;

- if (!cfs_rq)
+ if (cfs_rq->tg == &root_task_group)
return;

now = rq_of(cfs_rq)->clock;
@@ -830,9 +830,6 @@ static void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta)
struct sched_entity *se;
long shares;

- if (!cfs_rq)
- return;
-
tg = cfs_rq->tg;
se = tg->se[cpu_of(rq_of(cfs_rq))];
if (!se)