dect/linux-2.6
Archived
14
0
Fork 0
Code Releases Activity

[media] cx88: hold device lock during sub-driver initialization

Browse source 
cx8802_blackbird_probe makes a device node for the mpeg sub-device
before it has been added to dev->drvlist.  If the device is opened
during that time, the open succeeds but request_acquire cannot be
called, so the reference count remains zero.  Later, when the device
is closed, the reference count becomes negative --- uh oh.

Close the race by holding core->lock during probe and not releasing
until the device is in drvlist and initialization finished.
Previously the BKL prevented this race.

Reported-by: Andreas Huber <hobrom@gmx.at>
Tested-by: Andi Huber <hobrom@gmx.at>
Tested-by: Marlon de Boer <marlon@hyves.nl>
Cc: stable@kernel.org
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Jonathan Nieder 2011-05-01 06:29:56 -03:00 committed by Mauro Carvalho Chehab
parent 1fe70e9630
commit 1d6213ab99
3 changed files with 4 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
drivers/media/video/cx88/cx88-blackbird.c
View file

@ -1335,11 +1335,9 @@ static int cx8802_blackbird_probe(struct cx8802_driver *drv)
blackbird_register_video(dev);
/* initial device configuration: needed ? */
mutex_lock(&dev->core->lock);
// init_controls(core);
cx88_set_tvnorm(core,core->tvnorm);
cx88_video_mux(core,0);
mutex_unlock(&dev->core->lock);
return 0;

5
drivers/media/video/cx88/cx88-mpeg.c
View file

@ -709,18 +709,17 @@ int cx8802_register_driver(struct cx8802_driver *drv)
drv->request_release = cx8802_request_release;
memcpy(driver, drv, sizeof(*driver));
mutex_lock(&drv->core->lock);
err = drv->probe(driver);
if (err == 0) {
i++;
mutex_lock(&drv->core->lock);
list_add_tail(&driver->drvlist, &dev->drvlist);
mutex_unlock(&drv->core->lock);
} else {
printk(KERN_ERR
"%s/2: cx8802 probe failed, err = %d\n",
dev->core->name, err);
}
mutex_unlock(&drv->core->lock);
}
return i ? 0 : -ENODEV;

7
drivers/media/video/cx88/cx88.h
View file

@ -505,13 +505,10 @@ struct cx8802_driver {
int (*suspend)(struct pci_dev *pci_dev, pm_message_t state);
int (*resume)(struct pci_dev *pci_dev);
/* MPEG 8802 -> mini driver - Driver probe and configuration */
/* Caller must _not_ hold core->lock */
int (*probe)(struct cx8802_driver *drv);
/* Callers to the following functions must hold core->lock */
/* MPEG 8802 -> mini driver - Driver probe and configuration */
int (*probe)(struct cx8802_driver *drv);
int (*remove)(struct cx8802_driver *drv);
/* MPEG 8802 -> mini driver - Access for hardware control */