dm: consolidate target deregistration error handling

Change dm_unregister_target to return void and use BUG() for error
reporting.

dm_unregister_target can only fail because of programming bug in the
target driver. It can't fail because of user's behavior or disk errors.

This patch changes unregister_target to return void and use BUG if
someone tries to unregister non-registered target or unregister target
that is in use.

This patch removes code duplication (testing of error codes in all dm
targets) and reports bugs in just one place, in dm_unregister_target. In
some target drivers, these return codes were ignored, which could lead
to a situation where bugs could be missed.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 1 insertions, 4 deletions

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 44042becad8a..79fb53e51c70 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -156,8 +156,5 @@ int __init dm_linear_init(void)
 
 void dm_linear_exit(void)
 {
-        int r = dm_unregister_target(&linear_target);
-
-        if (r < 0)
-                DMERR("unregister failed %d", r);
+        dm_unregister_target(&linear_target);
 }