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[75.142.250.213]) by smtp.gmail.com with ESMTPSA id t127sm16326265qkc.100.2020.08.02.07.53.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 02 Aug 2020 07:53:50 -0700 (PDT) Subject: Re: [RFC PATCH 00/17] Drop uses of pci_read_config_*() return value To: Borislav Petkov , "Saheed O. Bolarinwa" Cc: helgaas@kernel.org, Kalle Valo , "David S. Miller" , Jakub Kicinski , Wolfgang Grandegger , Marc Kleine-Budde , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Joerg Roedel , bjorn@helgaas.com, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-mtd@lists.infradead.org, iommu@lists.linux-foundation.org, linux-rdma@vger.kernel.org, linux-ide@vger.kernel.org, linux-i2c@vger.kernel.org, linux-hwmon@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-gpio@vger.kernel.org, linux-fpga@vger.kernel.org, linux-edac@vger.kernel.org, dmaengine@vger.kernel.org, linux-crypto@vger.kernel.org, linux-atm-general@lists.sourceforge.net References: <20200801112446.149549-1-refactormyself@gmail.com> <20200801125657.GA25391@nazgul.tnic> From: Tom Rix Message-ID: <6ecce8f3-350a-b5d5-82c9-4609f2298e61@redhat.com> Date: Sun, 2 Aug 2020 07:53:46 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200801125657.GA25391@nazgul.tnic> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/1/20 5:56 AM, Borislav Petkov wrote: > On Sat, Aug 01, 2020 at 01:24:29PM +0200, Saheed O. Bolarinwa wrote: >> The return value of pci_read_config_*() may not indicate a device error. >> However, the value read by these functions is more likely to indicate >> this kind of error. This presents two overlapping ways of reporting >> errors and complicates error checking. > So why isn't the *value check done in the pci_read_config_* functions > instead of touching gazillion callers? > > For example, pci_conf{1,2}_read() could check whether the u32 *value it > just read depending on the access method, whether that value is ~0 and > return proper PCIBIOS_ error in that case. > > The check you're replicating > > if (val32 == (u32)~0) > > everywhere, instead, is just ugly and tests a naked value ~0 which > doesn't mean anything... > I agree, if there is a change, it should be in the pci_read_* functions. Anything returning void should not fail and likely future users of the proposed change will not do the extra checks. Tom