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, 4 insertions, 5 deletions

diff --git a/drivers/s390/net/smsgiucv_app.c b/drivers/s390/net/smsgiucv_app.c
index 4d2ea4000422..32515a201bbc 100644
--- a/drivers/s390/net/smsgiucv_app.c
+++ b/drivers/s390/net/smsgiucv_app.c
@@ -168,7 +168,7 @@ static int __init smsgiucv_app_init(void)
 	rc = dev_set_name(smsg_app_dev, KMSG_COMPONENT);
 	if (rc) {
 		kfree(smsg_app_dev);
-		goto fail_put_driver;
+		goto fail;
 	}
 	smsg_app_dev->bus = &iucv_bus;
 	smsg_app_dev->parent = iucv_root;
@@ -177,7 +177,7 @@ static int __init smsgiucv_app_init(void)
 	rc = device_register(smsg_app_dev);
 	if (rc) {
 		put_device(smsg_app_dev);
-		goto fail_put_driver;
+		goto fail;
 	}
 
 	/* convert sender to uppercase characters */
@@ -191,12 +191,11 @@ static int __init smsgiucv_app_init(void)
 	rc = smsg_register_callback(SMSG_PREFIX, smsg_app_callback);
 	if (rc) {
 		device_unregister(smsg_app_dev);
-		goto fail_put_driver;
+		goto fail;
 	}
 
 	rc = 0;
-fail_put_driver:
-	put_driver(smsgiucv_drv);
+fail:
 	return rc;
 }
 module_init(smsgiucv_app_init);