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Date: Tue, 20 Oct 2015 19:52:55 -0700
From: Geliang Tang <geliangtang@163.com>
To: Kees Cook <keescook@chromium.org>
Cc: Anton Vorontsov <anton@enomsg.org>, Colin Cross <ccross@android.com>,
        Tony Luck <tony.luck@intel.com>, Geliang Tang <geliangtang@163.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 0/3] pstore: add pstore unregister
Message-ID: <20151021025255.GA7402@ubuntu>
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On Tue, Oct 20, 2015 at 10:19:09AM -0700, Kees Cook wrote:
> On Tue, Oct 20, 2015 at 12:39 AM, Geliang Tang <geliangtang@163.com> wrote:
> > On Mon, Oct 19, 2015 at 10:56:54PM +0000, Luck, Tony wrote:
> >> Thanks for looking to close out this TODO item.
> >>
> >> The thing that scared me about unloading pstore was what happens to
> >> a process that is in the middle of reading some /sys/fs/pstore/file-name-here
> 
> Were you able to verify that this reading-while-rmmod case works correctly?
> 
> -Kees

$ sudo insmod zlib_deflate.ko
$ sudo insmod pstore.ko
$ lsmod
Module                  Size  Used by
pstore                 11225  0
zlib_deflate           18292  1 pstore

$ sudo mount -t pstore pstore /sys/fs/pstore
$ lsmod
Module                  Size  Used by
pstore                 11225  1
zlib_deflate           18292  1 pstore

$ sudo insmod reed_solomon.ko
$ sudo insmod ramoops.ko mem_address=0x40000000 mem_size=0x400000
$ lsmod
Module                  Size  Used by
ramoops                 9638  0
reed_solomon            5150  1 ramoops
pstore                 11225  2 ramoops
zlib_deflate           18292  1 pstore

$ tail -f /sys/fs/pstore/console-ramoops-0 &
[1] 3483
$ lsmod
Module                  Size  Used by
ramoops                 9638  0
reed_solomon            5150  1 ramoops
pstore                 11225  3 ramoops
zlib_deflate           18292  1 pstore

$ kill -9 3483
$ lsmod
Module                  Size  Used by
ramoops                 9638  0
reed_solomon            5150  1 ramoops
pstore                 11225  2 ramoops
zlib_deflate           18292  1 pstore

$ sudo rmmod ramoops
$ lsmod
Module                  Size  Used by
reed_solomon            5150  0
pstore                 11225  1
zlib_deflate           18292  1 pstore

$ sudo umount /sys/fs/pstore/
$ lsmod
Module                  Size  Used by
reed_solomon            5150  0 
pstore                 11225  0 
zlib_deflate           18292  1 pstore

$ sudo rmmod pstore
$ lsmod
Module                  Size  Used by
reed_solomon            5150  0 
zlib_deflate           18292  0

Thanks.
Geliang Tang