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From: Trond Myklebust <trondmy@hammerspace.com>
To: Dan Carpenter <error27@gmail.com>
Cc: "oe-kbuild@lists.linux.dev" <oe-kbuild@lists.linux.dev>,
	"lkp@intel.com" <lkp@intel.com>,
	"oe-kbuild-all@lists.linux.dev" <oe-kbuild-all@lists.linux.dev>
Subject: Re: [trondmy-nfs-2.6:testing 8/17] fs/nfs/read.c:358 nfs_read_folio() warn: variable dereferenced before check 'file' (see line 335)
Date: Wed, 11 Jan 2023 18:45:47 +0000	[thread overview]
Message-ID: <A846DACF-A13D-42BC-B1BA-A97A7956890E@hammerspace.com> (raw)
In-Reply-To: <Y77+n9MyHgx/alA4@kadam>



> On Jan 11, 2023, at 13:23, Dan Carpenter <error27@gmail.com> wrote:
> 
> On Wed, Jan 11, 2023 at 02:55:00PM +0000, Trond Myklebust wrote:
>> 
>> 
>>> On Jan 11, 2023, at 03:54, Dan Carpenter <error27@gmail.com> wrote:
>>> 
>>> [You don't often get email from error27@gmail.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>>> 
>>> tree:   git://git.linux-nfs.org/projects/trondmy/nfs-2.6.git testing
>>> head:   653d2b50cb73b541465920a748c6b1a1edf240d0
>>> commit: c87e83b9f933cc75e6c5ce2f99d333713e87cb6f [8/17] NFS: Convert buffered reads to use folios
>>> config: i386-randconfig-m021
>>> compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
>>> 
>>> If you fix the issue, kindly add following tag where applicable
>>> | Reported-by: kernel test robot <lkp@intel.com>
>>> | Reported-by: Dan Carpenter <error27@gmail.com>
>>> 
>>> smatch warnings:
>>> fs/nfs/read.c:358 nfs_read_folio() warn: variable dereferenced before check 'file' (see line 335)
>>> 
>>> 
> 
> [ snip ]
> 
>> 
>> I think that’s a false positive. From what I can see after auditing
>> all the callers, ‘file’ is guaranteed to be non-NULL, so the above
>> check should probably have been retired years ago.
> 
> When I build Smatch with the cross function DB then it silences the
> warning because Smatch also thinks "file" can't be NULL.
> 
> The cross function DB takes too long for the kbuild bot though so I only
> do that on my own system.
> 

Cool! I’ll add a patch to this series to just remove that check altogether.

Thanks, Dan!

_________________________________
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com


      reply	other threads:[~2023-01-11 18:45 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-11  8:35 [trondmy-nfs-2.6:testing 8/17] fs/nfs/read.c:358 nfs_read_folio() warn: variable dereferenced before check 'file' (see line 335) kernel test robot
2023-01-11  8:54 ` Dan Carpenter
2023-01-11 14:55 ` Trond Myklebust
2023-01-11 18:23   ` Dan Carpenter
2023-01-11 18:45     ` Trond Myklebust [this message]

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