Return-path: Received: from mail-qc0-f174.google.com ([209.85.216.174]:65486 "EHLO mail-qc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751333Ab2IHDeg convert rfc822-to-8bit (ORCPT ); Fri, 7 Sep 2012 23:34:36 -0400 Received: by qcro28 with SMTP id o28so154309qcr.19 for ; Fri, 07 Sep 2012 20:34:33 -0700 (PDT) MIME-Version: 1.0 Date: Sat, 8 Sep 2012 11:34:33 +0800 Message-ID: (sfid-20120908_053537_427742_401DBBBD) Subject: Re: [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test From: Wei Yongjun To: Larry.Finger@lwfinger.net Cc: lauro.venancio@openbossa.org, aloisio.almeida@openbossa.org, sameo@linux.intel.com, yongjun_wei@trendmicro.com.cn, linux-wireless@vger.kernel.org Content-Type: text/plain; charset=US-ASCII Sender: linux-wireless-owner@vger.kernel.org List-ID: On 09/08/2012 10:03 AM, Larry Finger wrote: > On 09/07/2012 08:53 PM, Wei Yongjun wrote: >> From: Wei Yongjun >> >> The dereference should be moved below the NULL test. >> >> spatch with a semantic match is used to found this. >> (http://coccinelle.lip6.fr/) >> >> Signed-off-by: Wei Yongjun >> --- >> > > As long as you are reworking this section, doesn't BUG_ON seem a little harsh? I do not think the kernel should ever be crashed because a non-essential driver is messed up. As the patch would be a totally different change, it should be a new submission, but I think each of these conditions should trigger a WARN_ON_ONCE, and return IRQ_NONE when they occur. > You means the should be like this? diff --git a/drivers/nfc/pn544_hci.c b/drivers/nfc/pn544_hci.c index aa71807..e42b100 100644 --- a/drivers/nfc/pn544_hci.c +++ b/drivers/nfc/pn544_hci.c @@ -341,13 +341,16 @@ flush: static irqreturn_t pn544_hci_irq_thread_fn(int irq, void *dev_id) { struct pn544_hci_info *info = dev_id; - struct i2c_client *client = info->i2c_dev; + struct i2c_client *client; struct sk_buff *skb = NULL; int r; - BUG_ON(!info); - BUG_ON(irq != info->i2c_dev->irq); + if (!info || irq != info->i2c_dev->irq) { + WARN_ON_ONCE(1); + return IRQ_NONE; + } + client = info->i2c_dev; dev_dbg(&client->dev, "IRQ\n"); if (info->hard_fault != 0)