linux-kernel - [tip:sched/core] sched/deadline: No need to check p if dl

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Date:	Thu, 16 Jan 2014 05:40:01 -0800
From:	tip-bot for Juri Lelli <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	peterz@...radead.org, tglx@...utronix.de, dan.carpenter@...cle.com,
	juri.lelli@...il.com
Subject: [tip:sched/core] sched/deadline:
  No need to check p if dl_se is valid

Commit-ID:  71362650b555a5b24c732e455484cc7cac1c8588
Gitweb:     http://git.kernel.org/tip/71362650b555a5b24c732e455484cc7cac1c8588
Author:     Juri Lelli <juri.lelli@...il.com>
AuthorDate: Tue, 14 Jan 2014 12:03:51 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 16 Jan 2014 09:27:11 +0100

sched/deadline: No need to check p if dl_se is valid

Dan Carpenter reported new 'Smatch' warnings:

  > tree:   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/core
  > head:   130816ce4d5f69167324f7272e70aa3d641677c6
  > commit: 1baca4ce16b8cc7d4f50be1f7914799af30a2861 [17/50] sched/deadline: Add SCHED_DEADLINE SMP-related data structures & logic
  >
  > kernel/sched/deadline.c:937 pick_next_task_dl() warn: variable dereferenced before check 'p' (see line 934)

BUG_ON() already fires if pick_next_dl_entity() doesn't return a valid
dl_se. No need to check if p is valid afterward.

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Juri Lelli <juri.lelli@...il.com>
Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Fixes: 1baca4ce16b8 ("sched/deadline: Add SCHED_DEADLINE SMP-related data structures & logic")
Link: http://lkml.kernel.org/r/52D54E25.6060100@gmail.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/deadline.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index ee25361..0de2482 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1007,8 +1007,7 @@ struct task_struct *pick_next_task_dl(struct rq *rq)
 	p->se.exec_start = rq_clock_task(rq);
 
 	/* Running task will never be pushed. */
-	if (p)
-		dequeue_pushable_dl_task(rq, p);
+       dequeue_pushable_dl_task(rq, p);
 
 #ifdef CONFIG_SCHED_HRTICK
 	if (hrtick_enabled(rq))
--
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