From 579b2b45120fa33f750cd65150d6d8995938750b Mon Sep 17 00:00:00 2001 From: Jonathan Nieder Date: Sun, 1 May 2011 06:30:46 -0300 Subject: [PATCH] [media] cx88: gracefully reject attempts to use unregistered cx88-blackbird driver It should not be possible to enter mpeg_open and acquire core->lock without the blackbird driver being registered, so just error out if it is not. This makes the code more readable and should prevent the bug fixed by the patch "hold device lock during sub-driver initialization" from resurfacing again. Similarly, if we enter mpeg_release and acquire core->lock then either the blackbird driver is registered (since open files keep it loaded) or the sysadmin forced the driver's removal. In the latter case the state will be inconsistent and this is worth a loud warning. Tested-by: Andi Huber Tested-by: Marlon de Boer Signed-off-by: Jonathan Nieder Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/cx88/cx88-blackbird.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/drivers/media/video/cx88/cx88-blackbird.c b/drivers/media/video/cx88/cx88-blackbird.c index f637d34d5062..fa8e347c448c 100644 --- a/drivers/media/video/cx88/cx88-blackbird.c +++ b/drivers/media/video/cx88/cx88-blackbird.c @@ -1060,18 +1060,21 @@ static int mpeg_open(struct file *file) /* Make sure we can acquire the hardware */ drv = cx8802_get_driver(dev, CX88_MPEG_BLACKBIRD); - if (drv) { - err = drv->request_acquire(drv); - if(err != 0) { - dprintk(1,"%s: Unable to acquire hardware, %d\n", __func__, err); - mutex_unlock(&dev->core->lock); - return err; - } + if (!drv) { + dprintk(1, "%s: blackbird driver is not loaded\n", __func__); + mutex_unlock(&dev->core->lock); + return -ENODEV; + } + + err = drv->request_acquire(drv); + if (err != 0) { + dprintk(1,"%s: Unable to acquire hardware, %d\n", __func__, err); + mutex_unlock(&dev->core->lock); + return err; } if (!atomic_read(&dev->core->mpeg_users) && blackbird_initialize_codec(dev) < 0) { - if (drv) - drv->request_release(drv); + drv->request_release(drv); mutex_unlock(&dev->core->lock); return -EINVAL; } @@ -1080,8 +1083,7 @@ static int mpeg_open(struct file *file) /* allocate + initialize per filehandle data */ fh = kzalloc(sizeof(*fh),GFP_KERNEL); if (NULL == fh) { - if (drv) - drv->request_release(drv); + drv->request_release(drv); mutex_unlock(&dev->core->lock); return -ENOMEM; } @@ -1125,6 +1127,7 @@ static int mpeg_release(struct file *file) /* Make sure we release the hardware */ drv = cx8802_get_driver(dev, CX88_MPEG_BLACKBIRD); + WARN_ON(!drv); if (drv) drv->request_release(drv); -- 2.11.0