sched: Fix/remove redundant cfs_rq checks
Paul Turner [Sat, 22 Jan 2011 04:45:00 +0000 (20:45 -0800)]
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

index ccecfec..1997383 100644 (file)
@@ -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)