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@xxxxxx>
Tested-by: Andi Huber <hobrom@xxxxxx>
Tested-by: Marlon de Boer <marlon@xxxxxxxx>
Cc: stable@xxxxxxxxxx
Signed-off-by: Jonathan Nieder <jrnieder@xxxxxxxxx>
---
drivers/media/video/cx88/cx88-blackbird.c | 2 --
drivers/media/video/cx88/cx88-mpeg.c | 5 ++---
drivers/media/video/cx88/cx88.h | 7 ++-----
3 files changed, 4 insertions(+), 10 deletions(-)
diff --git a/drivers/media/video/cx88/cx88-blackbird.c b/drivers/media/video/cx88/cx88-blackbird.c
index a6f7d53..f637d34 100644
--- a/drivers/media/video/cx88/cx88-blackbird.c
+++ b/drivers/media/video/cx88/cx88-blackbird.c
@@ -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;
diff --git a/drivers/media/video/cx88/cx88-mpeg.c b/drivers/media/video/cx88/cx88-mpeg.c
index 9147c16..497f26f 100644
--- a/drivers/media/video/cx88/cx88-mpeg.c
+++ b/drivers/media/video/cx88/cx88-mpeg.c
@@ -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;
diff --git a/drivers/media/video/cx88/cx88.h b/drivers/media/video/cx88/cx88.h
index e912919..93a94bf 100644
--- a/drivers/media/video/cx88/cx88.h
+++ b/drivers/media/video/cx88/cx88.h
@@ -495,13 +495,10 @@ struct cx8802_driver {
int (*suspend)(struct pci_dev *pci_dev, pm_message_t state);
int (*resume)(struct pci_dev *pci_dev);
+ /* Callers to the following functions must hold core->lock */
+
/* 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 */
-
int (*remove)(struct cx8802_driver *drv);
/* MPEG 8802 -> mini driver - Access for hardware control */
--
1.7.5
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
