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X-CSE-ConnectionGUID: VkilXhyZQyiTSeR8h91QOA== X-CSE-MsgGUID: pHBNXWmMT6m9z5JpGeoiDg== X-IronPort-AV: E=McAfee;i="6700,10204,11369"; a="53281777" X-IronPort-AV: E=Sophos;i="6.14,237,1736841600"; d="scan'208";a="53281777" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Mar 2025 13:28:36 -0700 X-CSE-ConnectionGUID: Io1LQZW1SMCWx8jlCrJC6w== X-CSE-MsgGUID: TkRSYNbZTDiqa6hIOx+iIQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,237,1736841600"; d="scan'208";a="157305575" Received: from aschofie-mobl2.amr.corp.intel.com (HELO aschofie-mobl2.lan) ([10.125.111.66]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Mar 2025 13:28:35 -0700 Date: Mon, 10 Mar 2025 13:28:33 -0700 From: Alison Schofield To: Shiju Jose Cc: "linux-cxl@vger.kernel.org" , "dan.j.williams@intel.com" , "dave@stgolabs.net" , Jonathan Cameron , "dave.jiang@intel.com" , "vishal.l.verma@intel.com" , "ira.weiny@intel.com" , "david@redhat.com" , "Vilas.Sridharan@amd.com" , "linux-edac@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "bp@alien8.de" , "tony.luck@intel.com" , "rafael@kernel.org" , "lenb@kernel.org" , "mchehab@kernel.org" , "leo.duran@amd.com" , "Yazen.Ghannam@amd.com" , "rientjes@google.com" , "jiaqiyan@google.com" , "Jon.Grimm@amd.com" , "dave.hansen@linux.intel.com" , "naoya.horiguchi@nec.com" , "james.morse@arm.com" , "jthoughton@google.com" , "somasundaram.a@hpe.com" , "erdemaktas@google.com" , "pgonda@google.com" , "duenwen@google.com" , "gthelen@google.com" , "wschwartz@amperecomputing.com" , "dferguson@amperecomputing.com" , "wbs@os.amperecomputing.com" , "nifan.cxl@gmail.com" , tanxiaofei , "Zengtao (B)" , Roberto Sassu , "kangkang.shen@futurewei.com" , wanghuiqiang , Linuxarm Subject: Re: [PATCH 1/8] cxl: Add helper function to retrieve a feature entry Message-ID: References: <20250227223816.2036-1-shiju.jose@huawei.com> <20250227223816.2036-2-shiju.jose@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: 7A2D91C000D X-Rspamd-Server: rspam08 X-Stat-Signature: 9d1ma8c1km9si53i4b3d7hfxszuir3yi X-HE-Tag: 1741638518-541684 X-HE-Meta: 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 kAz5AxMY mWC7YKTnXs3gJQiue4ZDwJwa3Nhkf9cAx6VurboZMkmLx9Fz++Zzly7oSUDrq77Pjd/mwcF7ntq7OSDHgAqHM46eZcBsA5ANzjyDrQapG2u4HDAu4LNFSea8Zjmc1L1pO1uWTksm9D6ki1WsUw2yBpidyMTDGTH/caJuFNyVOwTgX72nc3W7ULHrRiO4X5v05NZs5Q3ohK++F+SEzoQkp8q2TUf/3/Xer5rYSBOdjrAjP/eb/v2U/B6Vy84vlkZuWusf+PQCNIQtjw/X/8nYxalTsquuYweL7KGFLvaO8ymWFukL0rT9VAFEn24jsJUBqefcCa8nn8mGke0Ivr5v85uO7VePXJSmHOFU1LybkA+KVH6o= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000073, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 10, 2025 at 06:15:38PM +0000, Shiju Jose wrote: > >-----Original Message----- > >From: Alison Schofield > >Sent: 07 March 2025 19:20 > >To: Shiju Jose > [...] > >> +struct cxl_feat_entry *cxl_get_feature_entry(struct cxl_dev_state *cxlds, > >> + const uuid_t *feat_uuid) > >> +{ > >> + struct cxl_features_state *cxlfs = to_cxlfs(cxlds); > >> + struct cxl_feat_entry *feat_entry; > >> + int count; > >> + > >> + /* > >> + * Retrieve the feature entry from the supported features list, > >> + * if the feature is supported. > >> + */ > >> + feat_entry = cxlfs->entries->ent; > > > >Do we need some NULL checking here on cxlfs, entries > > Hi Alison, > > Thanks for the feedbacks. > We had check on cxlfs before > https://lore.kernel.org/all/20250122235159.2716036-5-dave.jiang@intel.com/ > but removed because of the following comment. > https://lore.kernel.org/all/20250124150150.GZ5556@nvidia.com/ Hi Shiju, I have not followed all along, so yeah my questions may be a bit pesky at this point. I did see the comment linked above about how the driver must be bound at this point. I think my question is a bit different. Are each of these guaranteed not to be NULL here: to_cxlfs(cxlds) cxlfs->entries cxlfs->entries->ent If these cannot be NULL, then all good. --Alison > > > > > >> + for (count = 0; count < cxlfs->entries->num_features; count++, > >> +feat_entry++) { > > > >Was num_features previously validated? > Not in the caller. Had check for num_features here before in cxl_get_feature_entry() > as seen in the above link. > > > >> + if (uuid_equal(&feat_entry->uuid, feat_uuid)) > >> + return feat_entry; > >> + } > >> + > >> + return ERR_PTR(-ENOENT); > > > >Why not just return NULL? > Will do. > > > > > >> +} > >> + > >> size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid, > >> enum cxl_get_feat_selection selection, > >> void *feat_out, size_t feat_out_size, u16 offset, > >> -- > >> 2.43.0 > >> > > Thanks, > Shiju >