2021-03-17 07:37:22

by Jiapeng Chong

Subject: [PATCH v2] sched: replace if (cond) BUG() with WARN_ON()

Fix the following coccicheck warnings:

./arch/powerpc/platforms/cell/spufs/sched.c:908:2-5: WARNING: Use BUG_ON
instead of if condition followed by BUG.

Reported-by: Abaci Robot <[email protected]>
Signed-off-by: Jiapeng Chong <[email protected]>
---
Changes in v2:
- replace BUG with WARN_ON.

arch/powerpc/platforms/cell/spufs/sched.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 3692064..1031448 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -904,8 +904,7 @@ static noinline void spusched_tick(struct spu_context *ctx)
struct spu_context *new = NULL;
struct spu *spu = NULL;

- if (spu_acquire(ctx))
- BUG(); /* a kernel thread never has signals pending */
+ WARN_ON(spu_acquire(ctx)); /* a kernel thread never has signals pending */

if (ctx->state != SPU_STATE_RUNNABLE)
goto out;
--
1.8.3.1

2021-03-17 07:59:30

by Arnd Bergmann

Subject: Re: [PATCH v2] sched: replace if (cond) BUG() with WARN_ON()

On Wed, Mar 17, 2021 at 8:35 AM Jiapeng Chong
<[email protected]> wrote:
>
> Fix the following coccicheck warnings:
>
> ./arch/powerpc/platforms/cell/spufs/sched.c:908:2-5: WARNING: Use BUG_ON
> instead of if condition followed by BUG.
>
> Reported-by: Abaci Robot <[email protected]>
> Signed-off-by: Jiapeng Chong <[email protected]>

If you change it from BUG() to WARN_ON(), you should explain why it's safe to
do that in this case. Here it is not, since the following spu_release() will
end up making things worse if the acquire failed. Also if there was a signal
pending, then spusched_tick() will just get called again and constantly
print these warnings.

There is probably a way to use WARN_ON_ONCE() here, in combination
with a way to terminate the thread safely, but this has to be done carefully.

Arnd