Patch "fs: dlm: add check if dlm is currently running" has been added to the 5.12-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    fs: dlm: add check if dlm is currently running

to the 5.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     fs-dlm-add-check-if-dlm-is-currently-running.patch
and it can be found in the queue-5.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 461150f82badac4bb8b9752cdda8c209218277a6
Author: Alexander Aring <aahringo@xxxxxxxxxx>
Date:   Mon Mar 1 17:05:13 2021 -0500

    fs: dlm: add check if dlm is currently running
    
    [ Upstream commit 517461630d1c25ee4dfc1dee80973a64189d6ccf ]
    
    This patch adds checks for dlm config attributes regarding to protocol
    parameters as it makes only sense to change them when dlm is not running.
    It also adds a check for valid protocol specifiers and return invalid
    argument if they are not supported.
    
    Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx>
    Signed-off-by: David Teigland <teigland@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/dlm/config.c b/fs/dlm/config.c
index 8439610c266a..88d95d96e36c 100644
--- a/fs/dlm/config.c
+++ b/fs/dlm/config.c
@@ -164,6 +164,36 @@ static ssize_t cluster_##name##_show(struct config_item *item, char *buf)     \
 }                                                                             \
 CONFIGFS_ATTR(cluster_, name);
 
+static int dlm_check_protocol_and_dlm_running(unsigned int x)
+{
+	switch (x) {
+	case 0:
+		/* TCP */
+		break;
+	case 1:
+		/* SCTP */
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (dlm_allow_conn)
+		return -EBUSY;
+
+	return 0;
+}
+
+static int dlm_check_zero_and_dlm_running(unsigned int x)
+{
+	if (!x)
+		return -EINVAL;
+
+	if (dlm_allow_conn)
+		return -EBUSY;
+
+	return 0;
+}
+
 static int dlm_check_zero(unsigned int x)
 {
 	if (!x)
@@ -180,7 +210,7 @@ static int dlm_check_buffer_size(unsigned int x)
 	return 0;
 }
 
-CLUSTER_ATTR(tcp_port, dlm_check_zero);
+CLUSTER_ATTR(tcp_port, dlm_check_zero_and_dlm_running);
 CLUSTER_ATTR(buffer_size, dlm_check_buffer_size);
 CLUSTER_ATTR(rsbtbl_size, dlm_check_zero);
 CLUSTER_ATTR(recover_timer, dlm_check_zero);
@@ -188,7 +218,7 @@ CLUSTER_ATTR(toss_secs, dlm_check_zero);
 CLUSTER_ATTR(scan_secs, dlm_check_zero);
 CLUSTER_ATTR(log_debug, NULL);
 CLUSTER_ATTR(log_info, NULL);
-CLUSTER_ATTR(protocol, NULL);
+CLUSTER_ATTR(protocol, dlm_check_protocol_and_dlm_running);
 CLUSTER_ATTR(mark, NULL);
 CLUSTER_ATTR(timewarn_cs, dlm_check_zero);
 CLUSTER_ATTR(waitwarn_us, NULL);
diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index a4fabcced0f2..0f7fa23cccf0 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -135,7 +135,7 @@ static DEFINE_SPINLOCK(dlm_node_addrs_spin);
 static struct listen_connection listen_con;
 static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
 static int dlm_local_count;
-static int dlm_allow_conn;
+int dlm_allow_conn;
 
 /* Work queues */
 static struct workqueue_struct *recv_workqueue;
diff --git a/fs/dlm/lowcomms.h b/fs/dlm/lowcomms.h
index 790d6703b17e..bcd4dbd1dc98 100644
--- a/fs/dlm/lowcomms.h
+++ b/fs/dlm/lowcomms.h
@@ -14,6 +14,9 @@
 
 #define LOWCOMMS_MAX_TX_BUFFER_LEN	4096
 
+/* switch to check if dlm is running */
+extern int dlm_allow_conn;
+
 int dlm_lowcomms_start(void);
 void dlm_lowcomms_stop(void);
 void dlm_lowcomms_exit(void);