From: Stefan Hajnoczi <stefanha@gmail.com>
Date: Wed, 23 Nov 2011 08:20:45 +0000 (+0000)
Subject: staging: line6: alloc/free buffers in hw_params/hw_free
X-Git-Tag: v3.3-rc1~152^2~101^2~355
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=140e28b83c4a31831cbf293d9cab20c603821202;p=pandora-kernel.git

staging: line6: alloc/free buffers in hw_params/hw_free

It is unsafe to free buffers in line6_pcm_stop(), which is not allowed
to sleep, since urbs cannot be killed completely there and only
unlinked.  This means I/O may still be in progress and the URB
completion function still gets invoked.  This may result in memory
corruption when buffer_in is freed but I/O is still pending.

Additionally, line6_pcm_start() is not supposed to sleep so it should
not use kmalloc(GFP_KERNEL).

These issues can be resolved by performing buffer allocation/freeing in
the .hw_params/.hw_free callbacks instead.  The ALSA documentation also
recommends doing buffer allocation/freeing in these callbacks.

Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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