linux-kernel - RE: [PATCH] tools: fix -Wunused-result in linux.c

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Message-ID: <13ddebb3e15b4a94b466c6ee5f3f2f42@AcuMS.aculab.com>
Date: Mon, 21 Oct 2024 16:10:18 +0000
From: David Laight <David.Laight@...LAB.COM>
To: "'Liam R. Howlett'" <Liam.Howlett@...cle.com>, Shuah Khan
	<skhan@...uxfoundation.org>
CC: "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "vbabka@...e.cz"
	<vbabka@...e.cz>, "sidhartha.kumar@...cle.com" <sidhartha.kumar@...cle.com>,
	"lorenzo.stoakes@...cle.com" <lorenzo.stoakes@...cle.com>,
	"zhangpeng.00@...edance.com" <zhangpeng.00@...edance.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] tools: fix -Wunused-result in linux.c

From: Liam R. Howlett
> Sent: 15 October 2024 02:11
> 
> * Shuah Khan <skhan@...uxfoundation.org> [241011 18:52]:
> > Fix the following -Wunused-result warnings on posix_memalign()
> > return values and add error handling.
> >
> > ./shared/linux.c:100:25: warning: ignoring return value of ‘posix_memalign’ declared with attribute
> ‘warn_unused_result’ [-Wunused-result]
> >   100 |          posix_memalign(&p, cachep->align, cachep->size);
> >       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > ../shared/linux.c: In function ‘kmem_cache_alloc_bulk’:
> > ../shared/linux.c:198:33: warning: ignoring return value of ‘posix_memalign’ declared with attribute
> ‘warn_unused_result’ [-Wunused-result]
> >   198 |          posix_memalign(&p[i], cachep->align,
> >       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >   199 |                                cachep->size);
> >       |                                ~~~~~~~~~~~~~
> >
> > Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
> 
> Reviewed-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> 
> > ---
> >  tools/testing/shared/linux.c | 14 +++++++++-----
> >  1 file changed, 9 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/testing/shared/linux.c b/tools/testing/shared/linux.c
> > index 17263696b5d8..66dbb362385f 100644
> > --- a/tools/testing/shared/linux.c
> > +++ b/tools/testing/shared/linux.c
> > @@ -96,10 +96,13 @@ void *kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru,
> >  		p = node;
> >  	} else {
> >  		pthread_mutex_unlock(&cachep->lock);
> > -		if (cachep->align)
> > -			posix_memalign(&p, cachep->align, cachep->size);
> > -		else
> > +		if (cachep->align) {
> > +			if (posix_memalign(&p, cachep->align, cachep->size) < 0)
> > +				return NULL;
> > +		} else {
> >  			p = malloc(cachep->size);
> > +		}
> > +

You really ought to be checking malloc() as well.
Perhaps:
		if (...) {
			if (posix_memalign(...) < 0)
				p = NULL;
		} else {
			p = malloc(...);
		}
		if (!p)
			return NULL;

Or just use a hack to get the compiler to STFU :-)

	David

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