Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753736AbdLMUaH (ORCPT ); Wed, 13 Dec 2017 15:30:07 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:46686 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752932AbdLMUaG (ORCPT ); Wed, 13 Dec 2017 15:30:06 -0500 Subject: Re: [PATCH][mtd-next] mtd: nand: remove redundant check of len To: Boris Brezillon Cc: Richard Weinberger , David Woodhouse , Brian Norris , Marek Vasut , Cyrille Pitchen , linux-mtd@lists.infradead.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org References: <20171213201743.27324-1-colin.king@canonical.com> <20171213212425.6fe999cb@bbrezillon> From: Colin Ian King Message-ID: Date: Wed, 13 Dec 2017 20:30:04 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171213212425.6fe999cb@bbrezillon> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1467 Lines: 53 On 13/12/17 20:24, Boris Brezillon wrote: > On Wed, 13 Dec 2017 20:17:43 +0000 > Colin King wrote: > >> From: Colin Ian King >> >> The check of len being zero is redundant as it has already been >> sanity checked for this value at the start of the function. Hence >> it is impossible for this test to be true and so the redundant >> code can be removed. > > Nope, it's not the same test, the initial test is > > if (len && !buf) Ah, the current tip from linux-next has: 1912 if (!len || !buf) 1913 return -EINVAL; ..so I guess that's why it got picked up by static analysis. > > not > > if (len) > > So this test is not redundant. > >> >> Detected by CoverityScan, CID#1462748 ("Logically dead code") >> >> Signed-off-by: Colin Ian King >> --- >> drivers/mtd/nand/nand_base.c | 4 ---- >> 1 file changed, 4 deletions(-) >> >> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c >> index afd5e18db81c..9daaa23db943 100644 >> --- a/drivers/mtd/nand/nand_base.c >> +++ b/drivers/mtd/nand/nand_base.c >> @@ -1507,10 +1507,6 @@ static int nand_read_param_page_op(struct nand_chip *chip, u8 page, void *buf, >> }; >> struct nand_operation op = NAND_OPERATION(instrs); >> >> - /* Drop the DATA_IN instruction if len is set to 0. */ >> - if (!len) >> - op.ninstrs--; >> - >> return nand_exec_op(chip, &op); >> } >> >