Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753001AbdHRNP6 (ORCPT ); Fri, 18 Aug 2017 09:15:58 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55215 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751969AbdHRNPk (ORCPT ); Fri, 18 Aug 2017 09:15:40 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Hans Verkuil" , "Arnd Bergmann" , "Mauro Carvalho Chehab" Date: Fri, 18 Aug 2017 14:13:20 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 001/134] [media] pvrusb2: reduce stack usage pvr2_eeprom_analyze() In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2064 Lines: 55 3.16.47-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Arnd Bergmann commit 6830733d53a4517588e56227b9c8538633f0c496 upstream. The driver uses a relatively large data structure on the stack, which showed up on my radar as we get a warning with the "latent entropy" GCC plugin: drivers/media/usb/pvrusb2/pvrusb2-eeprom.c:153:1: error: the frame size of 1376 bytes is larger than 1152 bytes [-Werror=frame-larger-than=] The warning is usually hidden as we raise the warning limit to 2048 when the plugin is enabled, but I'd like to lower that again in the future, and making this function smaller helps to do that without build regressions. Further analysis shows that putting an 'i2c_client' structure on the stack is not really supported, as the embedded 'struct device' is not initialized here, and we are only saved by the fact that the function that is called here does not use the pointer at all. Fixes: d855497edbfb ("V4L/DVB (4228a): pvrusb2 to kernel 2.6.18") Signed-off-by: Arnd Bergmann Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Ben Hutchings --- drivers/media/usb/pvrusb2/pvrusb2-eeprom.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) --- a/drivers/media/usb/pvrusb2/pvrusb2-eeprom.c +++ b/drivers/media/usb/pvrusb2/pvrusb2-eeprom.c @@ -123,15 +123,10 @@ int pvr2_eeprom_analyze(struct pvr2_hdw memset(&tvdata,0,sizeof(tvdata)); eeprom = pvr2_eeprom_fetch(hdw); - if (!eeprom) return -EINVAL; + if (!eeprom) + return -EINVAL; - { - struct i2c_client fake_client; - /* Newer version expects a useless client interface */ - fake_client.addr = hdw->eeprom_addr; - fake_client.adapter = &hdw->i2c_adap; - tveeprom_hauppauge_analog(&fake_client,&tvdata,eeprom); - } + tveeprom_hauppauge_analog(NULL, &tvdata, eeprom); trace_eeprom("eeprom assumed v4l tveeprom module"); trace_eeprom("eeprom direct call results:");