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Date: Wed, 31 Jan 2007 21:42:51 +0300
From: Alexey Dobriyan <adobriyan@gmail.com>
To: Duncan Sands <duncan.sands@math.u-psud.fr>
Cc: linux-kernel@vger.kernel.org
Subject: Re: remove_proc_entry and read_proc
Message-ID: <20070131184251.GA5544@martell.zuzino.mipt.ru>
References: <200701311154.35929.duncan.sands@math.u-psud.fr>
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On Wed, Jan 31, 2007 at 11:54:35AM +0100, Duncan Sands wrote:
> Can read_proc still be executing when remove_proc_entry returns?
>
> In my driver [*] I allocate some data and create a proc entry using
> create_proc_entry.  My read method reads from my allocated data.  When
> shutting down, I call remove_proc_entry and immediately free the data.
> If some call to read_proc is still executing at this point then it will
> be accessing freed memory.  Can this happen?  I've been rummaging around
> in fs/proc to see what prevents it, but didn't find anything yet.

This should be fixed by the following patch (in -mm currently):
http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.20-rc6/2.6.20-rc6-mm3/broken-out/fix-rmmod-read-write-races-in-proc-entries.patch

Tell me if you're unsure it will.

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