Driver core: driver_find() drops reference before returning

As part of the removal of get_driver()/put_driver(), this patch
(as1510) changes driver_find(); it now drops the reference it acquires
before returning.  The patch also adjusts all the callers of
driver_find() to remove the now unnecessary calls to put_driver().

In addition, the patch adds a warning to driver_find(): Callers must
make sure the driver they are searching for does not get unloaded
while they are using it.  This has always been the case; driver_find()
has never prevented a driver from being unregistered or unloaded.
Hence the patch will not introduce any new bugs.  The existing callers
all seem to be okay in this respect, however I don't understand the
video drivers well enough to be certain about them.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Dmitry Torokhov <dmitry.torokhov@gmail.com>
CC: Kyungmin Park <kyungmin.park@samsung.com>
CC: Andy Walls <awalls@md.metrocast.net>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 0 insertions, 2 deletions

diff --git a/drivers/media/video/ivtv/ivtvfb.c b/drivers/media/video/ivtv/ivtvfb.c
index d0fbfcf7133..e5e7fa9e737 100644
--- a/drivers/media/video/ivtv/ivtvfb.c
+++ b/drivers/media/video/ivtv/ivtvfb.c
@@ -1293,7 +1293,6 @@ static int __init ivtvfb_init(void)
 
 	drv = driver_find("ivtv", &pci_bus_type);
 	err = driver_for_each_device(drv, NULL, &registered, ivtvfb_callback_init);
-	put_driver(drv);
 	if (!registered) {
 		printk(KERN_ERR "ivtvfb:  no cards found\n");
 		return -ENODEV;
@@ -1310,7 +1309,6 @@ static void ivtvfb_cleanup(void)
 
 	drv = driver_find("ivtv", &pci_bus_type);
 	err = driver_for_each_device(drv, NULL, NULL, ivtvfb_callback_cleanup);
-	put_driver(drv);
 }
 
 module_init(ivtvfb_init);