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[75.142.250.213]) by smtp.gmail.com with ESMTPSA id d135sm11795610qkg.117.2020.07.11.09.21.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 11 Jul 2020 09:21:08 -0700 (PDT) Subject: Re: [RESEND PATCH 1/2] fpga: dfl: pci: reduce the scope of variable 'ret' To: Xu Yilun Cc: mdf@kernel.org, linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org, lgoncalv@redhat.com References: <1594282337-32125-1-git-send-email-yilun.xu@intel.com> <1594282337-32125-2-git-send-email-yilun.xu@intel.com> <20200710051600.GA8689@yilunxu-OptiPlex-7050> From: Tom Rix Message-ID: <85d84892-14d0-3097-c4f9-cbb9092c9a5f@redhat.com> Date: Sat, 11 Jul 2020 09:21:07 -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: <20200710051600.GA8689@yilunxu-OptiPlex-7050> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ok, i take your point on the api. However I still feel that this change should be improved so the return is not defined inside a block. I think this could be done better with int ret = num_vfs; ... return ret; There is no consistency on this check with the other drivers' sriov_configure. I do not feel strongly about this change, your original change will work. So you may add. Reviewed-by: Tom Rix Tom On 7/9/20 10:16 PM, Xu Yilun wrote: > On Thu, Jul 09, 2020 at 06:18:18AM -0700, Tom Rix wrote: >> I think a better change is to use the ret variable, like this >> >> --- a/drivers/fpga/dfl-pci.c >> +++ b/drivers/fpga/dfl-pci.c >> @@ -312,7 +312,7 @@ static int cci_pci_sriov_configure(struct pci_dev *pcidev, int num_vfs) >>                 } >>         } >>   >> -       return num_vfs; >> +       return ret; >>  } >> >> The existing use of returning num_vfs is not right, the function should return 0/err not num_vfs. currently it is reusing the 0 passed in with num_vfs to mean disable as the 0 return status.  it should be properly returning ret. > The sriov_configure callback should return negative value for error, and > return num_vfs if success. > > See the Documentation/PCI/pci-iov-howto.rst > > also in drivers/pci/iov.c: > > static ssize_t sriov_numvfs_store(struct device *dev, ...) > { > ... > > ret = pdev->driver->sriov_configure(pdev, num_vfs); > if (ret < 0) > goto exit; > > if (ret != num_vfs) > pci_warn(pdev, "%d VFs requested; only %d enabled\n", > num_vfs, ret); > > ... > } > >> Tom >> >> On 7/9/20 1:12 AM, Xu Yilun wrote: >>> This is to fix lkp cppcheck warnings: >>> >>> drivers/fpga/dfl-pci.c:230:6: warning: The scope of the variable 'ret' can be reduced. [variableScope] >>> int ret = 0; >>> ^ >>> >>> drivers/fpga/dfl-pci.c:230:10: warning: Variable 'ret' is assigned a value that is never used. [unreadVariable] >>> int ret = 0; >>> ^ >>> >>> Fixes: 3c2760b78f90 ("fpga: dfl: pci: fix return value of cci_pci_sriov_configure") >>> Reported-by: kbuild test robot >>> Signed-off-by: Xu Yilun >>> Acked-by: Wu Hao >>> --- >>> drivers/fpga/dfl-pci.c | 3 ++- >>> 1 file changed, 2 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/fpga/dfl-pci.c b/drivers/fpga/dfl-pci.c >>> index 4a14a24..73b5153 100644 >>> --- a/drivers/fpga/dfl-pci.c >>> +++ b/drivers/fpga/dfl-pci.c >>> @@ -285,7 +285,6 @@ static int cci_pci_sriov_configure(struct pci_dev *pcidev, int num_vfs) >>> { >>> struct cci_drvdata *drvdata = pci_get_drvdata(pcidev); >>> struct dfl_fpga_cdev *cdev = drvdata->cdev; >>> - int ret = 0; >>> >>> if (!num_vfs) { >>> /* >>> @@ -297,6 +296,8 @@ static int cci_pci_sriov_configure(struct pci_dev *pcidev, int num_vfs) >>> dfl_fpga_cdev_config_ports_pf(cdev); >>> >>> } else { >>> + int ret; >>> + >>> /* >>> * before enable SRIOV, put released ports into VF access mode >>> * first of all.