From: Julien Brunel Date: Mon, 01 Sep 2008 08:57:27 +0000 Subject: [PATCH] drivers/usb/misc: Use an IS_ERR test rather than a NULL test Message-Id: <200809011057.28293.brunel@diku.dk> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: gregkh@suse.de, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org From: Julien Brunel In case of error, the function backlight_device_register returns an ERR pointer, but never returns a NULL pointer. So a NULL test that may come after a call to this function should be strengthened by an IS_ERR test. The semantic match that finds this problem is as follows: (http://www.emn.fr/x-info/coccinelle/) // @match_bad_null_test@ expression x, E; statement S1,S2; @@ x = backlight_device_register(...) ... when != x = E * if (x != NULL) S1 else S2 // Signed-off-by: Julien Brunel Signed-off-by: Julia Lawall --- drivers/usb/misc/appledisplay.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -u -p a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c --- a/drivers/usb/misc/appledisplay.c +++ b/drivers/usb/misc/appledisplay.c @@ -314,7 +314,7 @@ error: pdata->urbdata, pdata->urb->transfer_dma); usb_free_urb(pdata->urb); } - if (pdata->bd) + if (pdata->bd && !IS_ERR(pdata->bd)) backlight_device_unregister(pdata->bd); kfree(pdata->msgdata); }