From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763726AbZFQX0u (ORCPT ); Wed, 17 Jun 2009 19:26:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755710AbZFQX0a (ORCPT ); Wed, 17 Jun 2009 19:26:30 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:60310 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753304AbZFQX02 (ORCPT ); Wed, 17 Jun 2009 19:26:28 -0400 Message-Id: <20090617232630.249960331@goodmis.org> References: <20090617232555.164629684@goodmis.org> User-Agent: quilt/0.46-1 Date: Wed, 17 Jun 2009 19:25:59 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Frederic Weisbecker Subject: [PATCH 4/7] ring-buffer: check for less than two in size allocation Content-Disposition: inline; filename=0004-ring-buffer-check-for-less-than-two-in-size-allocati.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt The ring buffer must have at least two pages allocated for the reader page swap to work. The page count check will miss the case of a zero size passed in. Even though a zero size ring buffer would probably fail an allocation, making the min size check for less than two instead of equal to one makes the code a bit more robust. Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 162da23..2e99dba 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -657,8 +657,8 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, buffer->reader_lock_key = key; /* need at least two pages */ - if (buffer->pages == 1) - buffer->pages++; + if (buffer->pages < 2) + buffer->pages = 2; /* * In case of non-hotplug cpu, if the ring-buffer is allocated -- 1.6.3.1 --