linux-kernel - [PATCH 6.6 083/638] s390/dasd: fix double module refcount decrement

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Date: Sun, 24 Mar 2024 18:52:00 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Miroslav Franc <mfranc@...e.cz>,
	Jan Höppner <hoeppner@...ux.ibm.com>,
	Stefan Haberland <sth@...ux.ibm.com>,
	Jens Axboe <axboe@...nel.dk>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH 6.6 083/638] s390/dasd: fix double module refcount decrement

From: Miroslav Franc <mfranc@...e.cz>

[ Upstream commit c3116e62ddeff79cae342147753ce596f01fcf06 ]

Once the discipline is associated with the device, deleting the device
takes care of decrementing the module's refcount.  Doing it manually on
this error path causes refcount to artificially decrease on each error
while it should just stay the same.

Fixes: c020d722b110 ("s390/dasd: fix panic during offline processing")
Signed-off-by: Miroslav Franc <mfranc@...e.cz>
Signed-off-by: Jan Höppner <hoeppner@...ux.ibm.com>
Signed-off-by: Stefan Haberland <sth@...ux.ibm.com>
Link: https://lore.kernel.org/r/20240209124522.3697827-3-sth@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/s390/block/dasd.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 96f4c94865846..6f97456798917 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -3528,12 +3528,11 @@ int dasd_generic_set_online(struct ccw_device *cdev,
 		dasd_delete_device(device);
 		return -EINVAL;
 	}
+	device->base_discipline = base_discipline;
 	if (!try_module_get(discipline->owner)) {
-		module_put(base_discipline->owner);
 		dasd_delete_device(device);
 		return -EINVAL;
 	}
-	device->base_discipline = base_discipline;
 	device->discipline = discipline;
 
 	/* check_device will allocate block device if necessary */
@@ -3541,8 +3540,6 @@ int dasd_generic_set_online(struct ccw_device *cdev,
 	if (rc) {
 		dev_warn(dev, "Setting the DASD online with discipline %s failed with rc=%i\n",
 			 discipline->name, rc);
-		module_put(discipline->owner);
-		module_put(base_discipline->owner);
 		dasd_delete_device(device);
 		return rc;
 	}
-- 
2.43.0