mm/hmm/test: fix error handling in dmirror_device_init

dmirror_device_init() calls device_initialize() which sets the device
reference count to 1, but fails to call put_device() when error occurs
after dev_set_name() or cdev_device_add() failures.  This results in
memory leaks of struct device objects.  Additionally,
dmirror_device_remove() lacks the final put_device() call to properly
release the device reference.

Found by code review.

Link: https://lkml.kernel.org/r/20251108115346.6368-1-make24@iscas.ac.cn
Fixes: 6a760f58c792 ("mm/hmm/test: use char dev with struct device to get device node")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
Cc: Haoxiang Li <make24@iscas.ac.cn>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Mika Penttilä <mpenttil@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 72a8b2f38d8a98bd802f05038060ef894f1c9745..8af169d3873ae459a4001822c735347fe9955bad 100644 (file)
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -1740,20 +1740,25 @@ static int dmirror_device_init(struct dmirror_device *mdevice, int id)
 
        ret = dev_set_name(&mdevice->device, "hmm_dmirror%u", id);
        if (ret)
-               return ret;
+               goto put_device;
 
        ret = cdev_device_add(&mdevice->cdevice, &mdevice->device);
        if (ret)
-               return ret;
+               goto put_device;
 
        /* Build a list of free ZONE_DEVICE struct pages */
        return dmirror_allocate_chunk(mdevice, NULL, false);
+
+put_device:
+       put_device(&mdevice->device);
+       return ret;
 }
 
 static void dmirror_device_remove(struct dmirror_device *mdevice)
 {
        dmirror_device_remove_chunks(mdevice);
        cdev_device_del(&mdevice->cdevice, &mdevice->device);
+       put_device(&mdevice->device);
 }
 
 static int __init hmm_dmirror_init(void)