From: Matthew Wilcox <matthew@wil.cx>
To: ?????? shin hong <hongshin@gmail.com>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: BUG? a suspected race bug at alloc_fd()
Date: Fri, 7 Aug 2009 05:08:12 -0600 [thread overview]
Message-ID: <20090807110812.GR3711@parisc-linux.org> (raw)
In-Reply-To: <2014bcab0908062155n6973cb7cg43bc5dcb19261a72@mail.gmail.com>
On Fri, Aug 07, 2009 at 01:55:10PM +0900, ?????? shin hong wrote:
> In alloc_fd(), spin_lock(&files->file_lock) synchronizes
> the execution of its gurading code block(line 448~486 at fs/file.c).
>
> However, by invocation of expand_files() at line 458,
> spin_lock(&file->file_lock) can be released and re-taken
> since expand_files() invokes expand_fdtable() and expand_fdtable()
> release &files->file_lock and re-take the lock (line 206~208).
>
> For this reason, the execution of alloc_fd() might result race condition
> if other threads are scheduled between the lock releasing and re-taking.
/*
* If we needed to expand the fs array we
* might have blocked - try again.
*/
if (error)
goto repeat;
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
prev parent reply other threads:[~2009-08-07 11:08 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-07 4:55 BUG? a suspected race bug at alloc_fd() 홍신 shin hong
2009-08-07 11:08 ` Matthew Wilcox [this message]
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