linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH] slab: fix 'dubious: x & !y' warning from Sparse
@ 2018-11-16  5:40 Masahiro Yamada
  2018-11-16  8:39 ` Michal Hocko
  2018-11-16 13:51 ` Christopher Lameter
  0 siblings, 2 replies; 4+ messages in thread
From: Masahiro Yamada @ 2018-11-16  5:40 UTC (permalink / raw)
  To: Christoph Lameter, Pekka Enberg, David Rientjes, Joonsoo Kim,
	Andrew Morton, linux-mm
  Cc: Masahiro Yamada, linux-kernel

Sparse reports:
./include/linux/slab.h:332:43: warning: dubious: x & !y

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 include/linux/slab.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 918f374..d395c73 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -329,7 +329,7 @@ static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
 	 * If an allocation is both __GFP_DMA and __GFP_RECLAIMABLE, return
 	 * KMALLOC_DMA and effectively ignore __GFP_RECLAIMABLE
 	 */
-	return type_dma + (is_reclaimable & !is_dma) * KMALLOC_RECLAIM;
+	return type_dma + (is_reclaimable && !is_dma) * KMALLOC_RECLAIM;
 }
 
 /*
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 4+ messages in thread

* Re: [PATCH] slab: fix 'dubious: x & !y' warning from Sparse
  2018-11-16  5:40 [PATCH] slab: fix 'dubious: x & !y' warning from Sparse Masahiro Yamada
@ 2018-11-16  8:39 ` Michal Hocko
  2018-11-16 13:51 ` Christopher Lameter
  1 sibling, 0 replies; 4+ messages in thread
From: Michal Hocko @ 2018-11-16  8:39 UTC (permalink / raw)
  To: Masahiro Yamada
  Cc: Christoph Lameter, Pekka Enberg, David Rientjes, Joonsoo Kim,
	Andrew Morton, linux-mm, linux-kernel

On Fri 16-11-18 14:40:29, Masahiro Yamada wrote:
> Sparse reports:
> ./include/linux/slab.h:332:43: warning: dubious: x & !y

JFYI this has been discussed here http://lkml.kernel.org/r/20181105204000.129023-1-bvanassche@acm.org

> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
> 
>  include/linux/slab.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 918f374..d395c73 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -329,7 +329,7 @@ static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
>  	 * If an allocation is both __GFP_DMA and __GFP_RECLAIMABLE, return
>  	 * KMALLOC_DMA and effectively ignore __GFP_RECLAIMABLE
>  	 */
> -	return type_dma + (is_reclaimable & !is_dma) * KMALLOC_RECLAIM;
> +	return type_dma + (is_reclaimable && !is_dma) * KMALLOC_RECLAIM;
>  }
>  
>  /*
> -- 
> 2.7.4

-- 
Michal Hocko
SUSE Labs

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] slab: fix 'dubious: x & !y' warning from Sparse
  2018-11-16  5:40 [PATCH] slab: fix 'dubious: x & !y' warning from Sparse Masahiro Yamada
  2018-11-16  8:39 ` Michal Hocko
@ 2018-11-16 13:51 ` Christopher Lameter
  2018-11-16 17:04   ` Michal Hocko
  1 sibling, 1 reply; 4+ messages in thread
From: Christopher Lameter @ 2018-11-16 13:51 UTC (permalink / raw)
  To: Masahiro Yamada
  Cc: Pekka Enberg, David Rientjes, Joonsoo Kim, Andrew Morton,
	linux-mm, linux-kernel

On Fri, 16 Nov 2018, Masahiro Yamada wrote:

> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 918f374..d395c73 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -329,7 +329,7 @@ static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
>  	 * If an allocation is both __GFP_DMA and __GFP_RECLAIMABLE, return
>  	 * KMALLOC_DMA and effectively ignore __GFP_RECLAIMABLE
>  	 */
> -	return type_dma + (is_reclaimable & !is_dma) * KMALLOC_RECLAIM;
> +	return type_dma + (is_reclaimable && !is_dma) * KMALLOC_RECLAIM;
>  }

Ok then lets revert the initial patch whose point was to avoid a branch.
&& causes a branch again.


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] slab: fix 'dubious: x & !y' warning from Sparse
  2018-11-16 13:51 ` Christopher Lameter
@ 2018-11-16 17:04   ` Michal Hocko
  0 siblings, 0 replies; 4+ messages in thread
From: Michal Hocko @ 2018-11-16 17:04 UTC (permalink / raw)
  To: Christopher Lameter
  Cc: Masahiro Yamada, Pekka Enberg, David Rientjes, Joonsoo Kim,
	Andrew Morton, linux-mm, linux-kernel

On Fri 16-11-18 13:51:19, Cristopher Lameter wrote:
> On Fri, 16 Nov 2018, Masahiro Yamada wrote:
> 
> > diff --git a/include/linux/slab.h b/include/linux/slab.h
> > index 918f374..d395c73 100644
> > --- a/include/linux/slab.h
> > +++ b/include/linux/slab.h
> > @@ -329,7 +329,7 @@ static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
> >  	 * If an allocation is both __GFP_DMA and __GFP_RECLAIMABLE, return
> >  	 * KMALLOC_DMA and effectively ignore __GFP_RECLAIMABLE
> >  	 */
> > -	return type_dma + (is_reclaimable & !is_dma) * KMALLOC_RECLAIM;
> > +	return type_dma + (is_reclaimable && !is_dma) * KMALLOC_RECLAIM;
> >  }
> 
> Ok then lets revert the initial patch whose point was to avoid a branch.
> && causes a branch again.

I believe Vlastimil managed to get rid of the branch http://lkml.kernel.org/r/aa5975b6-58ed-5a3e-7de1-4b1384f88457@suse.cz

-- 
Michal Hocko
SUSE Labs

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2018-11-16 17:04 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-11-16  5:40 [PATCH] slab: fix 'dubious: x & !y' warning from Sparse Masahiro Yamada
2018-11-16  8:39 ` Michal Hocko
2018-11-16 13:51 ` Christopher Lameter
2018-11-16 17:04   ` Michal Hocko

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).