[PATCH v2] sched: Use BUG_ON

Subsystems: cell broadband engine architecture, linux for powerpc (32-bit and 64-bit), spu file system, the rest

STALE1869d

2 messages, 2 authors, 2021-07-02 · open the first message on its own page

[PATCH v2] sched: Use BUG_ON

From: Jason Wang <hidden>
Date: 2021-07-01 14:12:03

The BUG_ON macro simplifies the if condition followed by BUG, so that
we can use BUG_ON instead of if condition followed by BUG.

Signed-off-by: Jason Wang <redacted>
---
 arch/powerpc/platforms/cell/spufs/sched.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 369206489895..0f218d9e5733 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -904,8 +904,8 @@ 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 */
+	/* a kernel thread never has signals pending */
+	BUG_ON(spu_acquire(ctx));
 
 	if (ctx->state != SPU_STATE_RUNNABLE)
 		goto out;
-- 
2.32.0


Re: [PATCH v2] sched: Use BUG_ON

From: Jeremy Kerr <jk@ozlabs.org>
Date: 2021-07-02 01:19:40

Hi Jason,
The BUG_ON macro simplifies the if condition followed by BUG, so that
we can use BUG_ON instead of if condition followed by BUG.
[...]
-       if (spu_acquire(ctx))
-               BUG();  /* a kernel thread never has signals pending */
+       /* a kernel thread never has signals pending */
+       BUG_ON(spu_acquire(ctx));
I'm not convinced that this is an improvement; you've combined the
acquire and the BUG into a single statement, and now it's no longer
clear what the comment applies to.

If you really wanted to use BUG_ON, something like this would be more
clear:

	rc = spu_acquire(ctx);
	/* a kernel thread never has signals pending */
	BUG_ON(rc);

but we don't have a suitable rc variable handy, so we'd need one of
those declared too. You could avoid that with:

	if (spu_acquire(ctx))
		BUG_ON(1); /* a kernel thread never has signals pending */

but wait: no need for the constant there, so this would be better:

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

wait, what are we doing again?

To me, this is a bit of shuffling code around, for no real benefit.

Regards,


Jeremy
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