linux-kernel - Re: [PATCH] sched: Use WARN

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Date:   Thu, 1 Jul 2021 14:57:59 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Jason Wang <wangborong@...rlc.com>, jk@...abs.org
Cc:     arnd@...db.de, linux-kernel@...r.kernel.org, paulus@...ba.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] sched: Use WARN_ON



Le 01/07/2021 à 14:50, Jason Wang a écrit :
> The BUG_ON macro simplifies the if condition followed by BUG, but it
> will lead to the kernel crashing. Therefore, we can try using WARN_ON
> instead of if condition followed by BUG.

But are you sure it is ok to continue if spu_acquire(ctx) returned false ?
Shouldn't there be at least for fallback handling ?

Something like:

	if (WARN_ON(spu_acquire(ctx)))
		return;


Christophe


> 
> Signed-off-by: Jason Wang <wangborong@...rlc.com>
> ---
>   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 */
> +	WARN_ON(spu_acquire(ctx));
>   
>   	if (ctx->state != SPU_STATE_RUNNABLE)
>   		goto out;
>