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[79.22.100.164]) by smtp.gmail.com with ESMTPSA id v12sm10292649ejq.36.2021.08.24.21.35.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Aug 2021 21:35:09 -0700 (PDT) From: "Fabio M. De Francesco" To: Larry.Finger@lwfinger.net, phil@philpotter.co.uk, gregkh@linuxfoundation.org, straube.linux@gmail.com, Pavel Skripkin Cc: linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 4/6] staging: r8188eu: add error handling of rtw_read16 Date: Wed, 25 Aug 2021 06:35:08 +0200 Message-ID: <1665728.ljvk3MsED4@localhost.localdomain> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, August 24, 2021 9:27:35 AM CEST Pavel Skripkin wrote: > _rtw_read16 function can fail in case of usb transfer failure. But > previous function prototype wasn't designed to return an error to > caller. It can cause a lot uninit value bugs all across the driver code, > since rtw_read16() returns local stack variable to caller. > > Fix it by changing the prototype of this function. Now it returns an > int: 0 on success, negative error value on failure and callers should pass > the pointer to storage location for register value. > > Signed-off-by: Pavel Skripkin > > [...] > > -static u16 usb_read16(struct intf_hdl *pintfhdl, u32 addr) > +static int usb_read16(struct intf_hdl *pintfhdl, u32 addr, u16 *data) > { > u8 requesttype; > u16 wvalue; > u16 len; > - __le32 data; > + int res; > + __le32 tmp; > + > + if (WARN_ON(unlikely(!data))) > + return -EINVAL; > > requesttype = 0x01;/* read_in */ > wvalue = (u16)(addr & 0x0000ffff); > len = 2; > - usbctrl_vendorreq(pintfhdl, wvalue, &data, len, requesttype); > + res = usbctrl_vendorreq(pintfhdl, wvalue, &tmp, len, requesttype); > + if (res < 0) { > + dev_err(dvobj_to_dev(pintfhdl->pintf_dev), "Failed to read 16 bytes: %d\n", res); > + return res; > + } else if (res != len) { Dear Pavel, Please note that if and when my patch "Use usb_control_msg_recv / send () in usbctrl_vendorreq ()" will be merged, "if (res! = len)" will always evaluate 'true' and usb_read16 () will always return -EIO even if usbctrl_vendorreq () succeeds. > + dev_err(dvobj_to_dev(pintfhdl->pintf_dev), > + "Failed to read 16 bytes, could read only %d bytes\n", res); > + return -EIO; > + } > > - return (u16)(le32_to_cpu(data) & 0xffff); > + *data = le32_to_cpu(tmp) & 0xffff; > + > + return 0; > } [...] Regards, Fabio