From: Steven Rostedt <srostedt@redhat.com>
Date: Fri, 30 Nov 2012 03:27:22 +0000 (-0500)
Subject: ring-buffer: Fix NULL pointer if rb_set_head_page() fails
X-Git-Tag: v3.2.36~77
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=51e8eac1d5138ab32debce67202b975c08920029;p=pandora-kernel.git

ring-buffer: Fix NULL pointer if rb_set_head_page() fails

commit 54f7be5b831254199522523ccab4c3d954bbf576 upstream.

The function rb_set_head_page() searches the list of ring buffer
pages for a the page that has the HEAD page flag set. If it does
not find it, it will do a WARN_ON(), disable the ring buffer and
return NULL, as this should never happen.

But if this bug happens to happen, not all callers of this function
can handle a NULL pointer being returned from it. That needs to be
fixed.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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