* [PATCH] sched: Use WARN_ON
@ 2021-07-01 12:50 ` Jason Wang
0 siblings, 0 replies; 6+ messages in thread
From: Jason Wang @ 2021-07-01 12:50 UTC (permalink / raw)
To: jk; +Cc: arnd, mpe, benh, paulus, linuxppc-dev, linux-kernel, Jason Wang
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.
Signed-off-by: Jason Wang <wangborong@cdjrlc.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;
--
2.32.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH] sched: Use WARN_ON
@ 2021-07-01 12:50 ` Jason Wang
0 siblings, 0 replies; 6+ messages in thread
From: Jason Wang @ 2021-07-01 12:50 UTC (permalink / raw)
To: jk; +Cc: arnd, linux-kernel, Jason Wang, paulus, linuxppc-dev
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.
Signed-off-by: Jason Wang <wangborong@cdjrlc.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;
--
2.32.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] sched: Use WARN_ON
2021-07-01 12:50 ` Jason Wang
@ 2021-07-01 12:57 ` Christophe Leroy
-1 siblings, 0 replies; 6+ messages in thread
From: Christophe Leroy @ 2021-07-01 12:57 UTC (permalink / raw)
To: Jason Wang, jk; +Cc: arnd, linux-kernel, paulus, linuxppc-dev
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@cdjrlc.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;
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] sched: Use WARN_ON
@ 2021-07-01 12:57 ` Christophe Leroy
0 siblings, 0 replies; 6+ messages in thread
From: Christophe Leroy @ 2021-07-01 12:57 UTC (permalink / raw)
To: Jason Wang, jk; +Cc: linuxppc-dev, paulus, linux-kernel, arnd
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@cdjrlc.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;
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] sched: Use WARN_ON
2021-07-01 12:57 ` Christophe Leroy
@ 2021-07-01 13:47 ` Arnd Bergmann
-1 siblings, 0 replies; 6+ messages in thread
From: Arnd Bergmann @ 2021-07-01 13:47 UTC (permalink / raw)
To: Christophe Leroy
Cc: Jason Wang, Jeremy Kerr, Linux Kernel Mailing List,
Paul Mackerras, linuxppc-dev
On Thu, Jul 1, 2021 at 2:57 PM Christophe Leroy
<christophe.leroy@csgroup.eu> wrote:
> 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;
I think you get a crash in either case:
- with the existing BUG_ON() there is an immediate backtrace and it stops there
- with WARN_ON() and continuing, you operate on a context that is not
valid
- with the 'return', you get an endless loop, as it keeps calling
spusched_tick()
without sleeping.
Out of those options, the existing BUG_ON() seems best.
Arnd
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] sched: Use WARN_ON
@ 2021-07-01 13:47 ` Arnd Bergmann
0 siblings, 0 replies; 6+ messages in thread
From: Arnd Bergmann @ 2021-07-01 13:47 UTC (permalink / raw)
To: Christophe Leroy
Cc: linuxppc-dev, Paul Mackerras, Jeremy Kerr, Jason Wang,
Linux Kernel Mailing List
On Thu, Jul 1, 2021 at 2:57 PM Christophe Leroy
<christophe.leroy@csgroup.eu> wrote:
> 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;
I think you get a crash in either case:
- with the existing BUG_ON() there is an immediate backtrace and it stops there
- with WARN_ON() and continuing, you operate on a context that is not
valid
- with the 'return', you get an endless loop, as it keeps calling
spusched_tick()
without sleeping.
Out of those options, the existing BUG_ON() seems best.
Arnd
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-07-01 13:48 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-01 12:50 [PATCH] sched: Use WARN_ON Jason Wang
2021-07-01 12:50 ` Jason Wang
2021-07-01 12:57 ` Christophe Leroy
2021-07-01 12:57 ` Christophe Leroy
2021-07-01 13:47 ` Arnd Bergmann
2021-07-01 13:47 ` Arnd Bergmann
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