From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754502Ab0C3Qme (ORCPT ); Tue, 30 Mar 2010 12:42:34 -0400 Received: from ppsw-0.csi.cam.ac.uk ([131.111.8.130]:43974 "EHLO ppsw-0.csi.cam.ac.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752764Ab0C3Qmc (ORCPT ); Tue, 30 Mar 2010 12:42:32 -0400 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: not scanned X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Message-ID: <4BB22A90.6070801@cam.ac.uk> Date: Tue, 30 Mar 2010 17:45:04 +0100 From: Jonathan Cameron User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20100109 Thunderbird/3.0 MIME-Version: 1.0 To: "linux-iio@vger.kernel.org" , LKML , Greg Kroah-Hartman Subject: [PATCH] Fix staging:iio:ring_sw: Fix incorrect test on successful read of last value, causes infinite loop X-Enigmail-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Jonathan Cameron --- This is a bad one. The test means that almost no reads of the last value ever succeed! Result is an infinite loop. Another one for the 'oops' category. Patch is post the spin lock fix: [PATCH] Staging: IIO: Fix uses of spinlocks prior to init in ring implementations drivers/staging/iio/ring_sw.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/staging/iio/ring_sw.c b/drivers/staging/iio/ring_sw.c index 7dff2bf..5abba8c 100644 --- a/drivers/staging/iio/ring_sw.c +++ b/drivers/staging/iio/ring_sw.c @@ -296,7 +296,7 @@ again: return -EAGAIN; memcpy(data, last_written_p_copy, ring->buf.bpd); - if (unlikely(ring->last_written_p >= last_written_p_copy)) + if (unlikely(ring->last_written_p != last_written_p_copy)) goto again; iio_unmark_sw_rb_in_use(&ring->buf); -- 1.6.4.4