Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755545Ab1FNAe2 (ORCPT ); Mon, 13 Jun 2011 20:34:28 -0400 Received: from smtp-out.google.com ([74.125.121.67]:37454 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753187Ab1FNAeZ convert rfc822-to-8bit (ORCPT ); Mon, 13 Jun 2011 20:34:25 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; b=pi9c1WwP/C2bWov/Cao1/CLNOuifj482WfflQC5bBXGBiUnc1EGnT2A5w9hY6oorHQ emIdPYHjoYZYOsnN0voQ== MIME-Version: 1.0 In-Reply-To: <20110613181212.571f8e76@s6510.ftrdhcpuser.net> References: <20110613181212.571f8e76@s6510.ftrdhcpuser.net> From: Greg Thelen Date: Mon, 13 Jun 2011 17:34:00 -0700 Message-ID: Subject: Re: [PATCH] sky2: avoid using uninitialized variable To: Stephen Hemminger Cc: Stephen Hemminger , netdev@vger.kernel.org, "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2325 Lines: 49 On Mon, Jun 13, 2011 at 3:12 PM, Stephen Hemminger wrote: > On Mon, 13 Jun 2011 14:21:59 -0700 > Greg Thelen wrote: > >> I am not sure if 0 or ~0 would be a better choice in the gm_phy_read() >> error case. ?I used 0. ?A more complete solution might be to plumb up >> error handling to the callers of gm_phy_read(). >> >> == >> From 37486219a3d93881f3b2619a4b2bb21be62db7d4 Mon Sep 17 00:00:00 2001 >> From: Greg Thelen >> Date: Mon, 13 Jun 2011 14:09:07 -0700 >> Subject: [PATCH] sky2: avoid using uninitialized variable >> >> Prior to this change gm_phy_read() could return an uninitialized >> variable if __gm_phy_read() failed. >> >> This change returns zero in the failure case. >> >> Signed-off-by: Greg Thelen > > Shouldn't the callers be changed to check rather than just returning > 0 and masking the problem. I agree that the right long term solution is to plumb the error handling up through the callers. This would involve deleting the error-free gm_phy_read() routine and replacing all calls to it with calls to error-capable __gm_phy_read(). This would require converting several routines from returning void to returning int allowing errors to propagate upwards. Notable affected routines include: sky2_phy_power_up(), sky2_wol_init(), sky2_phy_power_down(), sky2_hw_down(), sky2_mac_init(), sky2_hw_up(), sky2_phy_intr(), sky2_led(). sky2_restart() would likely have to re-queue the work item in the case of failure. Presumably sky2_poll() would return 0 if error is seen. On a related note, it also seems that gm_phy_write() callers should be checking its return value to also handle the same class of I/O errors. Testing these changes would involve injecting error values or access to certain kinds of broken hardware. For the short term I figured that not consuming random data was a step in right direction. But I understand if you prefer to hold out for the complete solution. Unfortunately, I do not currently have time to contribute to the complete solution. -- 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/