fs: dlm: fix mark setting deadlock

This patch fixes an deadlock issue when dlm_lowcomms_close() is called.
When dlm_lowcomms_close() is called the clusters_root.subsys.su_mutex is
held to remove configfs items. At this time we flushing (e.g.
cancel_work_sync()) the workers of send and recv workqueue. Due the fact
that we accessing configfs items (mark values), these workers will lock
clusters_root.subsys.su_mutex as well which are already hold by
dlm_lowcomms_close() and ends in a deadlock situation.

[67170.703046] ======================================================
[67170.703965] WARNING: possible circular locking dependency detected
[67170.704758] 5.11.0-rc4+ #22 Tainted: G        W
[67170.705433] ------------------------------------------------------
[67170.706228] dlm_controld/280 is trying to acquire lock:
[67170.706915] ffff9f2f475a6948 ((wq_completion)dlm_recv){+.+.}-{0:0}, at: __flush_work+0x203/0x4c0
[67170.708026]
               but task is already holding lock:
[67170.708758] ffffffffa132f878 (&clusters_root.subsys.su_mutex){+.+.}-{3:3}, at: configfs_rmdir+0x29b/0x310
[67170.710016]
               which lock already depends on the new lock.

The new behaviour adds the mark value to the node address configuration
which doesn't require to held the clusters_root.subsys.su_mutex by
accessing mark values in a separate datastructure. However the mark
values can be set now only after a node address was set which is the
case when the user is using dlm_controld.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

1 files changed, 10 insertions, 19 deletions

diff --git a/fs/dlm/config.c b/fs/dlm/config.c
index 49c5f9407098..582bffa09a66 100644
--- a/fs/dlm/config.c
+++ b/fs/dlm/config.c
@@ -688,6 +688,7 @@ static ssize_t comm_mark_show(struct config_item *item, char *buf)
 static ssize_t comm_mark_store(struct config_item *item, const char *buf,
 			       size_t len)
 {
+	struct dlm_comm *comm;
 	unsigned int mark;
 	int rc;
 
@@ -695,7 +696,15 @@ static ssize_t comm_mark_store(struct config_item *item, const char *buf,
 	if (rc)
 		return rc;
 
-	config_item_to_comm(item)->mark = mark;
+	if (mark == 0)
+		mark = dlm_config.ci_mark;
+
+	comm = config_item_to_comm(item);
+	rc = dlm_lowcomms_nodes_set_mark(comm->nodeid, mark);
+	if (rc)
+		return rc;
+
+	comm->mark = mark;
 	return len;
 }
 
@@ -870,24 +879,6 @@ int dlm_comm_seq(int nodeid, uint32_t *seq)
 	return 0;
 }
 
-void dlm_comm_mark(int nodeid, unsigned int *mark)
-{
-	struct dlm_comm *cm;
-
-	cm = get_comm(nodeid);
-	if (!cm) {
-		*mark = dlm_config.ci_mark;
-		return;
-	}
-
-	if (cm->mark)
-		*mark = cm->mark;
-	else
-		*mark = dlm_config.ci_mark;
-
-	put_comm(cm);
-}
-
 int dlm_our_nodeid(void)
 {
 	return local_comm ? local_comm->nodeid : 0;