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Tue, 24 Mar 2026 02:30:59 -0700 (PDT) X-Received: by 2002:a05:600c:a4a:b0:485:33ad:3c9f with SMTP id 5b1f17b1804b1-486fee1aed6mr204528485e9.25.1774344658667; Tue, 24 Mar 2026 02:30:58 -0700 (PDT) Received: from [192.168.88.32] ([212.105.153.60]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4870f81db8esm16734255e9.8.2026.03.24.02.30.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 24 Mar 2026 02:30:58 -0700 (PDT) Message-ID: <2232bb67-b82d-4ed9-9c88-85b37d3c824a@redhat.com> Date: Tue, 24 Mar 2026 10:30:56 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] nfc: pn533: add error handling for i2c_master_send() in pn533_i2c_send_ack() To: Wenyuan Li <2063309626@qq.com>, netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, gszhai@bjtu.edu.cn, 25125332@bjtu.edu.cn, 25125283@bjtu.edu.cn, 23120469@bjtu.edu.cn References: Content-Language: en-US From: Paolo Abeni In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/19/26 7:50 AM, Wenyuan Li wrote: > In pn533_i2c_send_ack(), the return value of i2c_master_send() is not > checked. If the I2C transfer fails, the driver continues execution > without detecting the error, which may lead to incorrect device state > or silent failures. > > Specifically: > 1. The ACK may not be sent to the device, leaving it in an undefined state > 2. The caller (pn533_i2c_abort_cmd()) ignores the return value entirely > 3. No error logging is provided for debugging > > Fix this by: > - Adding proper return value check for i2c_master_send() > - Converting partial sends to -EIO and preserving kernel error codes > - Adding nfc_err() logging with %pe format for human-readable errors > - Propagating the error to the caller pn533_i2c_abort_cmd() > > Even if ACK sending fails, the abort procedure continues by scheduling > cmd_complete_work to ensure userspace is notified, but the error is > properly logged for debugging. > > Signed-off-by: Wenyuan Li <2063309626@qq.com> > --- > drivers/nfc/pn533/i2c.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/drivers/nfc/pn533/i2c.c b/drivers/nfc/pn533/i2c.c > index 132c050a365d..4d771fe24f70 100644 > --- a/drivers/nfc/pn533/i2c.c > +++ b/drivers/nfc/pn533/i2c.c > @@ -40,8 +40,15 @@ static int pn533_i2c_send_ack(struct pn533 *dev, gfp_t flags) > struct i2c_client *client = phy->i2c_dev; > static const u8 ack[6] = {0x00, 0x00, 0xff, 0x00, 0xff, 0x00}; > /* spec 6.2.1.3: Preamble, SoPC (2), ACK Code (2), Postamble */ > + int ret; > > - return i2c_master_send(client, ack, 6); > + ret = i2c_master_send(client, ack, 6); > + if (ret != 6) { > + nfc_err(&client->dev, "failed to send ACK: %pe\n", ERR_PTR(ret)); > + return ret < 0 ? ret : -EIO; > + } > + > + return 0; > } > > static int pn533_i2c_send_frame(struct pn533 *dev, > @@ -82,12 +89,14 @@ static int pn533_i2c_send_frame(struct pn533 *dev, > static void pn533_i2c_abort_cmd(struct pn533 *dev, gfp_t flags) > { > struct pn533_i2c_phy *phy = dev->phy; > + int ret; > > phy->aborted = true; > > /* An ack will cancel the last issued command */ > - pn533_i2c_send_ack(dev, flags); > - > + ret = pn533_i2c_send_ack(dev, flags); > + if (ret) > + nfc_err(&phy->i2c_dev->dev, "failed to abort command: %pe\n", ERR_PTR(ret)); A single failure on abort_cmd() will emit 2 err messages, which is IMHO way too verbose. Also send_ack errors are still ignored in most cases, and errors from other phy (usb, uart) too. I'm sorry but I see little value here. /P