* [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 [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
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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
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