Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162479Ab1FAJEK (ORCPT ); Wed, 1 Jun 2011 05:04:10 -0400 Received: from cantor2.suse.de ([195.135.220.15]:43475 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162021Ab1FAIRI (ORCPT ); Wed, 1 Jun 2011 04:17:08 -0400 X-Mailbox-Line: From linux@blue.kroah.org Wed Jun 1 17:04:35 2011 Message-Id: <20110601080433.645288314@blue.kroah.org> User-Agent: quilt/0.48-16.4 Date: Wed, 01 Jun 2011 17:00:56 +0900 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jonathan Nieder , Mauro Carvalho Chehab , Greg Kroah-Hartman Subject: [120/146] [media] cx88: fix locking of sub-driver operations In-Reply-To: <20110601080606.GA522@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3782 Lines: 122 2.6.38-stable review patch. If anyone has any objections, please let us know. ------------------ From: Jonathan Nieder commit 1fe70e963028f34ba5e32488a7870ff4b410b19b upstream. The BKL conversion of this driver seems to have gone wrong. Loading the cx88-blackbird driver deadlocks. The cause: mpeg_ops::open in the cx2388x blackbird driver acquires the device lock and calls the sub-driver's request_acquire, which tries to acquire the lock again. Fix it by clarifying the semantics of request_acquire, request_release, advise_acquire, and advise_release: now all will rely on the caller to acquire the device lock. Based on work by Ben Hutchings . Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=31962 Reported-by: Andi Huber Tested-by: Andi Huber Tested-by: Marlon de Boer Signed-off-by: Jonathan Nieder Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Greg Kroah-Hartman --- drivers/media/video/cx88/cx88-blackbird.c | 4 ++-- drivers/media/video/cx88/cx88-dvb.c | 3 +-- drivers/media/video/cx88/cx88-mpeg.c | 4 ---- drivers/media/video/cx88/cx88.h | 3 ++- 4 files changed, 5 insertions(+), 9 deletions(-) --- a/drivers/media/video/cx88/cx88-blackbird.c +++ b/drivers/media/video/cx88/cx88-blackbird.c @@ -1125,13 +1125,13 @@ static int mpeg_release(struct file *fil /* Make sure we release the hardware */ drv = cx8802_get_driver(dev, CX88_MPEG_BLACKBIRD); - mutex_unlock(&dev->core->lock); - if (drv) drv->request_release(drv); atomic_dec(&dev->core->mpeg_users); + mutex_unlock(&dev->core->lock); + return 0; } --- a/drivers/media/video/cx88/cx88-dvb.c +++ b/drivers/media/video/cx88/cx88-dvb.c @@ -134,8 +134,6 @@ static int cx88_dvb_bus_ctrl(struct dvb_ mutex_lock(&dev->core->lock); drv = cx8802_get_driver(dev, CX88_MPEG_DVB); - mutex_unlock(&dev->core->lock); - if (drv) { if (acquire){ dev->frontends.active_fe_id = fe_id; @@ -145,6 +143,7 @@ static int cx88_dvb_bus_ctrl(struct dvb_ dev->frontends.active_fe_id = 0; } } + mutex_unlock(&dev->core->lock); return ret; } --- a/drivers/media/video/cx88/cx88-mpeg.c +++ b/drivers/media/video/cx88/cx88-mpeg.c @@ -624,13 +624,11 @@ static int cx8802_request_acquire(struct if (drv->advise_acquire) { - mutex_lock(&drv->core->lock); core->active_ref++; if (core->active_type_id == CX88_BOARD_NONE) { core->active_type_id = drv->type_id; drv->advise_acquire(drv); } - mutex_unlock(&drv->core->lock); mpeg_dbg(1,"%s() Post acquire GPIO=%x\n", __func__, cx_read(MO_GP0_IO)); } @@ -643,14 +641,12 @@ static int cx8802_request_release(struct { struct cx88_core *core = drv->core; - mutex_lock(&drv->core->lock); if (drv->advise_release && --core->active_ref == 0) { drv->advise_release(drv); core->active_type_id = CX88_BOARD_NONE; mpeg_dbg(1,"%s() Post release GPIO=%x\n", __func__, cx_read(MO_GP0_IO)); } - mutex_unlock(&drv->core->lock); return 0; } --- a/drivers/media/video/cx88/cx88.h +++ b/drivers/media/video/cx88/cx88.h @@ -500,7 +500,8 @@ struct cx8802_driver { /* Caller must _not_ hold core->lock */ int (*probe)(struct cx8802_driver *drv); - /* Caller must hold core->lock */ + /* Callers to the following functions must hold core->lock */ + int (*remove)(struct cx8802_driver *drv); /* MPEG 8802 -> mini driver - Access for hardware control */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/