nvdimm/pmem: fix leak on dax_add_host() failure

Fix a leak on dax_add_host() error, where "goto out_cleanup_dax" is done
before setting pmem->dax_dev, which therefore issues the two following
calls on NULL pointers:

out_cleanup_dax:
        kill_dax(pmem->dax_dev);
        put_dax(pmem->dax_dev);

Link: https://lkml.kernel.org/r/20240208184913.484340-1-mathieu.desnoyers@efficios.com
Link: https://lkml.kernel.org/r/20240208184913.484340-2-mathieu.desnoyers@efficios.comSigned-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/nvdimm/pmem.c

@@ -566,12 +566,11 @@ static int pmem_attach_disk(struct device *dev,
 	set_dax_nomc(dax_dev);
 	if (is_nvdimm_sync(nd_region))
 		set_dax_synchronous(dax_dev);
+	pmem->dax_dev = dax_dev;
 	rc = dax_add_host(dax_dev, disk);
 	if (rc)
 		goto out_cleanup_dax;
 	dax_write_cache(dax_dev, nvdimm_has_cache(nd_region));
-	pmem->dax_dev = dax_dev;
-
 	rc = device_add_disk(dev, disk, pmem_attribute_groups);
 	if (rc)
 		goto out_remove_host;