From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761999AbZAOAE5 (ORCPT ); Wed, 14 Jan 2009 19:04:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761435AbZAOADh (ORCPT ); Wed, 14 Jan 2009 19:03:37 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:62193 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758435AbZAOADe (ORCPT ); Wed, 14 Jan 2009 19:03:34 -0500 Message-Id: <20090115000332.355796420@goodmis.org> References: <20090115000254.519563275@goodmis.org> User-Agent: quilt/0.46-1 Date: Wed, 14 Jan 2009 19:02:56 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Frederic Weisbecker , Lai Jiangshan , Steven Rostedt Subject: [PATCH 2/4] ring_buffer: reset write when reserve buffer fail Content-Disposition: inline; filename=0002-ring_buffer-reset-write-when-reserve-buffer-fail.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan [ The following text is in the "UTF-8" character set. ] [ Your display is set for the "ANSI_X3.4-1968" character set. ] [ Some characters may be displayed incorrectly. ] Impact: reset struct buffer_page.write when interrupt storm if struct buffer_page.write is not reset, any succedent committing will corrupted ring_buffer: static inline void rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) { ...... cpu_buffer->commit_page->commit = cpu_buffer->commit_page->write; ...... } when "if (RB_WARN_ON(cpu_buffer, next_page == reader_page))", ring_buffer is disabled, but some reserved buffers may haven't been committed. we need reset struct buffer_page.write. when "if (unlikely(next_page == cpu_buffer->commit_page))", ring_buffer is still available, we should not corrupt it. Signed-off-by: Lai Jiangshan Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 10 +++++----- 1 files changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 4832ffa..0b9de5a 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1017,12 +1017,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, } if (next_page == head_page) { - if (!(buffer->flags & RB_FL_OVERWRITE)) { - /* reset write */ - if (tail <= BUF_PAGE_SIZE) - local_set(&tail_page->write, tail); + if (!(buffer->flags & RB_FL_OVERWRITE)) goto out_unlock; - } /* tail_page has not moved yet? */ if (tail_page == cpu_buffer->tail_page) { @@ -1097,6 +1093,10 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, return event; out_unlock: + /* reset write */ + if (tail <= BUF_PAGE_SIZE) + local_set(&tail_page->write, tail); + __raw_spin_unlock(&cpu_buffer->lock); local_irq_restore(flags); return NULL; -- 1.5.6.5 --