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| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2014-12-05 21:22:22 +0900 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-01-14 13:34:15 +0100 |
| commit | 1f8a7633094b7886c0677b78ba60b82e501f3ce6 (patch) | |
| tree | 35b1e774960265e9463b4985dca4f09c3d2b9f26 /kernel/sched | |
| parent | a8b686b3af4419f92e0ea5be1c76fb68363df8e6 (diff) | |
| download | op-kernel-dev-1f8a7633094b7886c0677b78ba60b82e501f3ce6.zip op-kernel-dev-1f8a7633094b7886c0677b78ba60b82e501f3ce6.tar.gz | |
sched/debug: Fix potential call to __ffs(0) in sched_show_task()
"struct task_struct"->state is "volatile long" and __ffs() warns that
"Undefined if no bit exists, so code should check against 0 first."
Therefore, at expression
state = p->state ? __ffs(p->state) + 1 : 0;
in sched_show_task(), CPU might see "p->state" before "?" as "non-zero"
but "p->state" after "?" as "zero", which could result in
"state >= sizeof(stat_nam)" being true and bogus '?' is printed.
This patch changes "state" from "unsigned int" to "unsigned long" and
save "p->state" before calling __ffs(), in order to avoid potential call
to __ffs(0).
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/201412052131.GCE35924.FVHFOtLOJOMQFS@I-love.SAKURA.ne.jp
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/core.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 56c9b79..816c172 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4508,9 +4508,10 @@ void sched_show_task(struct task_struct *p) { unsigned long free = 0; int ppid; - unsigned state; + unsigned long state = p->state; - state = p->state ? __ffs(p->state) + 1 : 0; + if (state) + state = __ffs(state) + 1; printk(KERN_INFO "%-15.15s %c", p->comm, state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?'); #if BITS_PER_LONG == 32 |
