linux-kernel - Re: linux-next: build warning after merge of the md tree

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Message-ID: <20170328154914.tkowin5hm5biybd6@kernel.org>
Date:   Tue, 28 Mar 2017 08:49:14 -0700
From:   Shaohua Li <shli@...nel.org>
To:     Ming Lei <tom.leiming@...il.com>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        linux-next@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: linux-next: build warning after merge of the md tree

On Tue, Mar 28, 2017 at 04:17:55PM +0800, Ming Lei wrote:
> Hi,
> 
> On Tue, Mar 28, 2017 at 03:40:22PM +1100, Stephen Rothwell wrote:
> > Hi Shaohua,
> > 
> > After merging the md tree, today's linux-next build (powerpc
> > pseries_le_defconfig) produced this warning:
> > 
> > drivers/md/raid1.c: In function 'raid1d':
> > drivers/md/raid1.c:2172:9: warning: 'page_len$' may be used uninitialized in this function [-Wmaybe-uninitialized]
> >      if (memcmp(page_address(ppages[j]),
> >          ^
> > drivers/md/raid1.c:2160:7: note: 'page_len$' was declared here
> >    int page_len[RESYNC_PAGES];
> >        ^
> > 
> > Introduced by commit
> > 
> >   60928a91b0b3 ("md: raid1: use bio helper in process_checks()")
> 
> It is a false positive, and looks we have to initialize it for killing
> the warning since I don't find a annotation for addressing uninitialized
> array.
> 
> So how about the following patch?

thanks, added.
 
> ---
> 
> From 73fd5ba571465d764fc0cf73fc4169d222dd676a Mon Sep 17 00:00:00 2001
> From: Ming Lei <tom.leiming@...il.com>
> Date: Tue, 28 Mar 2017 16:09:13 +0800
> Subject: [PATCH] md: raid1: kill warning on powerpc_pseries
> 
> This patch kills the warning reported on powerpc_pseries,
> and actually we don't need the initialization.
> 
> 	After merging the md tree, today's linux-next build (powerpc
> 	pseries_le_defconfig) produced this warning:
> 
> 	drivers/md/raid1.c: In function 'raid1d':
> 	drivers/md/raid1.c:2172:9: warning: 'page_len$' may be used uninitialized in this function [-Wmaybe-uninitialized]
> 	     if (memcmp(page_address(ppages[j]),
> 	         ^
> 	drivers/md/raid1.c:2160:7: note: 'page_len$' was declared here
> 	   int page_len[RESYNC_PAGES];
>        ^
> 
> Signed-off-by: Ming Lei <tom.leiming@...il.com>
> ---
>  drivers/md/raid1.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 3c13286190c1..7e6350334d8e 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -2172,7 +2172,7 @@ static void process_checks(struct r1bio *r1_bio)
>  		struct page **ppages = get_resync_pages(pbio)->pages;
>  		struct page **spages = get_resync_pages(sbio)->pages;
>  		struct bio_vec *bi;
> -		int page_len[RESYNC_PAGES];
> +		int page_len[RESYNC_PAGES] = { 0 };
>  
>  		if (sbio->bi_end_io != end_sync_read)
>  			continue;
> -- 
> 2.9.3
> 
>