Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754579AbZJ0HYj (ORCPT ); Tue, 27 Oct 2009 03:24:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753590AbZJ0HYj (ORCPT ); Tue, 27 Oct 2009 03:24:39 -0400 Received: from mail-pw0-f42.google.com ([209.85.160.42]:64075 "EHLO mail-pw0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753065AbZJ0HYi (ORCPT ); Tue, 27 Oct 2009 03:24:38 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type; b=Q2OOaythIHVn3UlK0dCkq5gxqV70tICzgir0dGQCy5mHbDAKHhKfR+xbOOso3bKn/a PMe/Ygwo18gkd/8gIng21AJcIQFBkX8cv1YJUmOsoCCCoqr0JNYWbkzZWSpGLFMRCHYX E0911ITNo7wAEa3CwTZvOVJOKIoSwXcJBOXt0= MIME-Version: 1.0 Date: Tue, 27 Oct 2009 00:24:43 -0700 Message-ID: Subject: Garbled printk output on 2.7.27 - No multi line printks From: "Leonidas ." To: linux-kernel Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1568 Lines: 35 Hi, I am trying a simple char driver and for debug purposes I have added lot of printks in my module. The module is rather heavily being used by my test app which does hundreds of open/read/write calls. The driver just copies and prints incoming/outgoing buffers. I see a lot of garbled output in /var/log/messages E.g. Oct 27 00:18:47 ubuntu-vm kernel: [ 4903.382917] returned buf "Hello" Oct 27 00:18:47 ubuntu-vm kernel: [ 4903.382925] returned buf "Hello" Oct 27 00:18:47 ubuntu-vm kernel: [ 4903.383033] returned buf "Hello" reeeeeeeeeexeeeeeeexteeeexeeeeeeeeeeeeeeeeeeeeeeeeeeeeexeeeeeeeeeeeeeeeeeexeeeeeeeeeexteexeeeeeeeeexeeeeeeeeeeeeeeeeeeeeeeexeeeeeeeeeeeexeeeeeeeeeeeexeeeeeeeeeeeeeeeeeeeeexeeeeeeeeeeeeeeeeeeexeeeeeeeeeexteeeeeeeeeeeeeeexeeeext for 8902 Hello Oct 27 00:18:47 ubuntu-vm kernel: [ d Oct 27 00:18:47 ubuntu-vm kernel: dddddddd Oct 27 00:18:47 ubuntu-vm kernel: ddddddddn3eexeeeeeeeeeeeeeeeexeeeeeeeeeeeeexeeeeexteeeeeeexeeeeeeeeeeeeeeeeeeeeeeeeeeexeeeeeeeeeexeeeeeeeeeeexeeeeeeeeeeeeexeeeeeeeeeeeeeexeeeeeeeeeexeeeeexeeeeeeeeeeeeeeeeeeeeeeexeeeeeeeeeeeeeeeeeeeeexeeeeeeeeeexeeeeeeeeeeeeeeeeexeeeeeeeext for 8903 Hello My loglevel is KERN_INFO, my understanding was a multiline printk might cause garbled output on SMPs but a single line printk is always protected using a semaphore. -Leo. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/