From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751402AbeBWKr3 (ORCPT ); Fri, 23 Feb 2018 05:47:29 -0500 Received: from lelnx193.ext.ti.com ([198.47.27.77]:32672 "EHLO lelnx193.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750903AbeBWKr1 (ORCPT ); Fri, 23 Feb 2018 05:47:27 -0500 Subject: Re: [PATCH 1/2] pci: endpoint: Free func_name after last usage To: Lorenzo Pieralisi References: <20180221124707.26308-1-embedded24@evers-fischer.de> <20180221124707.26308-2-embedded24@evers-fischer.de> <20180222181901.GA13694@e107981-ln.cambridge.arm.com> <9cdc8c1c-b448-b00b-d5b8-b664bd96f856@ti.com> <20180223093611.GA25086@e107981-ln.cambridge.arm.com> CC: Rolf Evers-Fischer , , , , Rolf Evers-Fischer From: Kishon Vijay Abraham I Message-ID: Date: Fri, 23 Feb 2018 16:17:15 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <20180223093611.GA25086@e107981-ln.cambridge.arm.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday 23 February 2018 03:06 PM, Lorenzo Pieralisi wrote: > On Fri, Feb 23, 2018 at 11:40:49AM +0530, Kishon Vijay Abraham I wrote: >> Hi Lorenzo, >> >> On Thursday 22 February 2018 11:49 PM, Lorenzo Pieralisi wrote: >>> On Wed, Feb 21, 2018 at 01:47:06PM +0100, Rolf Evers-Fischer wrote: >>>> From: Rolf Evers-Fischer >>>> >>>> This commit decreases the number of jump labels and ensures >>>> that the next commit doesn't increase the number of occurrences >>>> of 'kfree(func_name)'. >>>> >>>> Change-Id: I0d1b6fd652395b85f82b11c43bf9b7db512854d1 >>>> Signed-off-by: Rolf Evers-Fischer >>>> Signed-off-by: Rolf Evers-Fischer >>>> --- >>>> drivers/pci/endpoint/pci-epf-core.c | 7 ++----- >>>> 1 file changed, 2 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c >>>> index 766ce1dca2ec..23d0e128d1a5 100644 >>>> --- a/drivers/pci/endpoint/pci-epf-core.c >>>> +++ b/drivers/pci/endpoint/pci-epf-core.c >>>> @@ -220,9 +220,10 @@ struct pci_epf *pci_epf_create(const char *name) >>>> *buf = '\0'; >>>> >>>> epf->name = kstrdup(func_name, GFP_KERNEL); >>>> + kfree(func_name); >>> >>> I am certainly missing something but what if we reworked the code >>> and just: >>> >>> kstrdup(name, GFP_KERNEL); >>> >>> once instead of allocating another local copy (that we then have to >>> free) ? >> >> name will be something like pci_epf_test.0 and in epf->name we want to just >> have pci_epf_test. >>> >>> Reworded: why >>> >>> epf->name = func_name; >> >> memory should be allocated for epf->name before it can be initialized. IMO >> without kstrdup, there will be a null pointer exception. > > I understand that but the point is that func_name *was* allocated with > kstrdup() already I would like to understand why we need to do it twice > (and kfree the first allocation). func_name would be allocated for a size greater than what will be in epf->name. It won't be significant though. Thanks Kishon