From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753528AbbBKSNq (ORCPT ); Wed, 11 Feb 2015 13:13:46 -0500 Received: from mail.cybernetics.com ([173.71.130.66]:33145 "EHLO mail.cybernetics.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752452AbbBKSNo (ORCPT ); Wed, 11 Feb 2015 13:13:44 -0500 Message-ID: <54DB9BD7.7090605@cybernetics.com> Date: Wed, 11 Feb 2015 13:13:43 -0500 From: Tony Battersby User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: dgilbert@interlog.com, linux-scsi@vger.kernel.org, "James E.J. Bottomley" CC: linux-kernel@vger.kernel.org Subject: Re: [PATCH] [SCSI] sg: fix read() error reporting References: <54DB8406.4020804@cybernetics.com> <54DB953C.1090104@interlog.com> In-Reply-To: <54DB953C.1090104@interlog.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/11/2015 12:45 PM, Douglas Gilbert wrote: > On 15-02-11 11:32 AM, Tony Battersby wrote: >> Fix SCSI generic read() incorrectly returning success after detecting an >> error. >> >> Cc: >> Signed-off-by: Tony Battersby >> --- >> >> For inclusion in kernel 3.20. >> >> --- linux-3.19.0/drivers/scsi/sg.c.orig 2015-02-08 21:54:22.000000000 -0500 >> +++ linux-3.19.0/drivers/scsi/sg.c 2015-02-10 09:26:09.000000000 -0500 >> @@ -546,7 +546,7 @@ static ssize_t >> sg_new_read(Sg_fd * sfp, char __user *buf, size_t count, Sg_request * srp) >> { >> sg_io_hdr_t *hp = &srp->header; >> - int err = 0; >> + int err = 0, err2; >> int len; >> >> if (count < SZ_SG_IO_HDR) { >> @@ -575,8 +575,8 @@ sg_new_read(Sg_fd * sfp, char __user *bu >> goto err_out; >> } >> err_out: >> - err = sg_finish_rem_req(srp); >> - return (0 == err) ? count : err; >> + err2 = sg_finish_rem_req(srp); >> + return err ? : err2 ? : count; > Tony, > Your point is well made. > > I just don't like that last line, using a gcc extension that > hasn't even made it into C11 (or C++11). Wouldn't: > return err ? err : (err2 ? err2 : count); > > be a bit better? I think the following snippet makes the intent > clear but would it generate any more code: > if (err || err2) > return err ? err : err2; > else > return count; > > Doug Gilbert > > > I checked before submitting, and the foo ? : bar construct is already used at least 455 times in the kernel, so it is nothing new. find linux-3.19 -type f -name "*.[ch]" | xargs grep '\? :' | wc -l 455 But you are probably right; I think that with such small variable names your version is more readable due to the nesting. Updated patch below. --- Fix SCSI generic read() incorrectly returning success after detecting an error. Cc: Signed-off-by: Tony Battersby --- --- linux-3.19.0/drivers/scsi/sg.c.orig 2015-02-08 21:54:22.000000000 -0500 +++ linux-3.19.0/drivers/scsi/sg.c 2015-02-11 13:02:56.000000000 -0500 @@ -546,7 +546,7 @@ static ssize_t sg_new_read(Sg_fd * sfp, char __user *buf, size_t count, Sg_request * srp) { sg_io_hdr_t *hp = &srp->header; - int err = 0; + int err = 0, err2; int len; if (count < SZ_SG_IO_HDR) { @@ -575,8 +575,8 @@ sg_new_read(Sg_fd * sfp, char __user *bu goto err_out; } err_out: - err = sg_finish_rem_req(srp); - return (0 == err) ? count : err; + err2 = sg_finish_rem_req(srp); + return err ? err : (err2 ? err2 : count); } static ssize_t