From patchwork Wed Feb 26 11:01:47 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 3723381 Return-Path: X-Original-To: patchwork-linux-media@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 78DD2BF40C for ; Wed, 26 Feb 2014 11:04:54 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9C53C2014A for ; Wed, 26 Feb 2014 11:04:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA28F201D3 for ; Wed, 26 Feb 2014 11:04:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752150AbaBZLCw (ORCPT ); Wed, 26 Feb 2014 06:02:52 -0500 Received: from moutng.kundenserver.de ([212.227.126.130]:54782 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752064AbaBZLCt (ORCPT ); Wed, 26 Feb 2014 06:02:49 -0500 Received: from wuerfel.lan (HSI-KBW-5-56-226-176.hsi17.kabel-badenwuerttemberg.de [5.56.226.176]) by mrelayeu.kundenserver.de (node=mreue003) with ESMTP (Nemesis) id 0LapiO-1WyIkC25JA-00kN4m; Wed, 26 Feb 2014 12:02:41 +0100 From: Arnd Bergmann To: linux-kernel@vger.kernel.org Cc: Arnd Bergmann , Hans Verkuil , Mauro Carvalho Chehab , linux-media@vger.kernel.org Subject: [PATCH 07/16] [media] radio-cadet: avoid interruptible_sleep_on race Date: Wed, 26 Feb 2014 12:01:47 +0100 Message-Id: <1393412516-3762435-8-git-send-email-arnd@arndb.de> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1393412516-3762435-1-git-send-email-arnd@arndb.de> References: <1393412516-3762435-1-git-send-email-arnd@arndb.de> X-Provags-ID: V02:K0:1TBVnu7Ro34STCxwy7j8q1UgGEJZaysIfyuwdIhotto d1HUItnPnF0x7Kim4/O6I2a/DQmnPO7nxgZtlVc9gRDu2d2ltA XtLPqqKtcfP1Q3e0GF3DI9oNNnog3Vj+N2NZG338YbhNXdGpvV KHU3sCkrzThgAxYOV6Wr3a9uTUhGVA2WMkD6Iypf44LPGmX5et 2PwkHFa4jzjWkZ0L0gVEfCyDBbcuIym8bAzeh7k2C7PWlcuec8 lPx2yVE1ZRNZzUQ17jvSBSEG6wRBawm3bvN2TmCP/j2thFMzZL ybSjyPo3HxwHluC6DJRMBVBXvP1rSMPsDf47f8093jSexRtq/I MHEZwZNpsmGYx0v65UFrpujw3kTecUivq0OwbXSh1 Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP interruptible_sleep_on is racy and going away. This replaces one use in the radio-cadet driver with an wait_event_interruptible call that lets us check the condition under the mutex but sleep without it. The first version of this patch was done by Arnd, but Hans came up with a nicer solution. Signed-off-by: Hans Verkuil Signed-off-by: Arnd Bergmann Cc: Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org --- drivers/media/radio/radio-cadet.c | 46 +++++++++++++++++++++++---------------- 1 file changed, 27 insertions(+), 19 deletions(-) diff --git a/drivers/media/radio/radio-cadet.c b/drivers/media/radio/radio-cadet.c index 545c04c..d27e8b2 100644 --- a/drivers/media/radio/radio-cadet.c +++ b/drivers/media/radio/radio-cadet.c @@ -270,6 +270,16 @@ reset_rds: outb(inb(dev->io + 1) & 0x7f, dev->io + 1); } +static bool cadet_has_rds_data(struct cadet *dev) +{ + bool result; + + mutex_lock(&dev->lock); + result = dev->rdsin != dev->rdsout; + mutex_unlock(&dev->lock); + return result; +} + static void cadet_handler(unsigned long data) { @@ -279,13 +289,12 @@ static void cadet_handler(unsigned long data) if (mutex_trylock(&dev->lock)) { outb(0x3, dev->io); /* Select RDS Decoder Control */ if ((inb(dev->io + 1) & 0x20) != 0) - printk(KERN_CRIT "cadet: RDS fifo overflow\n"); + pr_err("cadet: RDS fifo overflow\n"); outb(0x80, dev->io); /* Select RDS fifo */ + while ((inb(dev->io) & 0x80) != 0) { dev->rdsbuf[dev->rdsin] = inb(dev->io + 1); - if (dev->rdsin + 1 == dev->rdsout) - printk(KERN_WARNING "cadet: RDS buffer overflow\n"); - else + if (dev->rdsin + 1 != dev->rdsout) dev->rdsin++; } mutex_unlock(&dev->lock); @@ -294,7 +303,7 @@ static void cadet_handler(unsigned long data) /* * Service pending read */ - if (dev->rdsin != dev->rdsout) + if (cadet_has_rds_data(dev)) wake_up_interruptible(&dev->read_queue); /* @@ -327,22 +336,21 @@ static ssize_t cadet_read(struct file *file, char __user *data, size_t count, lo mutex_lock(&dev->lock); if (dev->rdsstat == 0) cadet_start_rds(dev); - if (dev->rdsin == dev->rdsout) { - if (file->f_flags & O_NONBLOCK) { - i = -EWOULDBLOCK; - goto unlock; - } - mutex_unlock(&dev->lock); - interruptible_sleep_on(&dev->read_queue); - mutex_lock(&dev->lock); - } + mutex_unlock(&dev->lock); + + if (!cadet_has_rds_data(dev) && (file->f_flags & O_NONBLOCK)) + return -EWOULDBLOCK; + i = wait_event_interruptible(dev->read_queue, cadet_has_rds_data(dev)); + if (i) + return i; + + mutex_lock(&dev->lock); while (i < count && dev->rdsin != dev->rdsout) readbuf[i++] = dev->rdsbuf[dev->rdsout++]; + mutex_unlock(&dev->lock); if (i && copy_to_user(data, readbuf, i)) - i = -EFAULT; -unlock: - mutex_unlock(&dev->lock); + return -EFAULT; return i; } @@ -352,7 +360,7 @@ static int vidioc_querycap(struct file *file, void *priv, { strlcpy(v->driver, "ADS Cadet", sizeof(v->driver)); strlcpy(v->card, "ADS Cadet", sizeof(v->card)); - strlcpy(v->bus_info, "ISA", sizeof(v->bus_info)); + strlcpy(v->bus_info, "ISA:radio-cadet", sizeof(v->bus_info)); v->device_caps = V4L2_CAP_TUNER | V4L2_CAP_RADIO | V4L2_CAP_READWRITE | V4L2_CAP_RDS_CAPTURE; v->capabilities = v->device_caps | V4L2_CAP_DEVICE_CAPS; @@ -491,7 +499,7 @@ static unsigned int cadet_poll(struct file *file, struct poll_table_struct *wait cadet_start_rds(dev); mutex_unlock(&dev->lock); } - if (dev->rdsin != dev->rdsout) + if (cadet_has_rds_data(dev)) res |= POLLIN | POLLRDNORM; return res; }