drbd: Use RCU for the drbd_tconns list

Preparing removal of drbd_cfg_rwsem

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 8da0e99..771b53e 100644 (file)
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2341,7 +2341,7 @@ static void drbd_cleanup(void)
        }
 
        list_for_each_entry_safe(tconn, tmp, &drbd_tconns, all_tconn) {
-               list_del(&tconn->all_tconn);
+               list_del_rcu(&tconn->all_tconn);
                synchronize_rcu();
                kref_put(&tconn->kref, &conn_destroy);
        }
@@ -2409,7 +2409,7 @@ struct drbd_tconn *conn_get_by_name(const char *name)
                return NULL;
 
        down_read(&drbd_cfg_rwsem);
-       list_for_each_entry(tconn, &drbd_tconns, all_tconn) {
+       list_for_each_entry_rcu(tconn, &drbd_tconns, all_tconn) {
                if (!strcmp(tconn->name, name)) {
                        kref_get(&tconn->kref);
                        goto found;
@@ -2459,6 +2459,7 @@ void conn_free_crypto(struct drbd_tconn *tconn)
        tconn->int_dig_vv = NULL;
 }
 
+/* caller must be under genl_lock() */
 struct drbd_tconn *conn_create(const char *name)
 {
        struct drbd_tconn *tconn;
@@ -2503,7 +2504,7 @@ struct drbd_tconn *conn_create(const char *name)
 
        down_write(&drbd_cfg_rwsem);
        kref_init(&tconn->kref);
-       list_add_tail(&tconn->all_tconn, &drbd_tconns);
+       list_add_tail_rcu(&tconn->all_tconn, &drbd_tconns);
        up_write(&drbd_cfg_rwsem);
 
        return tconn;

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 5747bc6..a0cf000 100644 (file)
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -2674,7 +2674,7 @@ int get_one_status(struct sk_buff *skb, struct netlink_callback *cb)
        /* synchronize with conn_create()/conn_destroy() */
        down_read(&drbd_cfg_rwsem);
        /* revalidate iterator position */
-       list_for_each_entry(tmp, &drbd_tconns, all_tconn) {
+       list_for_each_entry_rcu(tmp, &drbd_tconns, all_tconn) {
                if (pos == NULL) {
                        /* first iteration */
                        pos = tmp;
@@ -2692,8 +2692,8 @@ next_tconn:
                if (!mdev) {
                        /* No more volumes to dump on this tconn.
                         * Advance tconn iterator. */
-                       pos = list_entry(tconn->all_tconn.next,
-                                       struct drbd_tconn, all_tconn);
+                       pos = list_entry_rcu(tconn->all_tconn.next,
+                                            struct drbd_tconn, all_tconn);
                        /* Did we dump any volume on this tconn yet? */
                        if (volume != 0) {
                                /* If we reached the end of the list,
@@ -3130,7 +3130,8 @@ int drbd_adm_down(struct sk_buff *skb, struct genl_info *info)
 
        /* delete connection */
        if (conn_lowest_minor(adm_ctx.tconn) < 0) {
-               list_del(&adm_ctx.tconn->all_tconn);
+               list_del_rcu(&adm_ctx.tconn->all_tconn);
+               synchronize_rcu();
                kref_put(&adm_ctx.tconn->kref, &conn_destroy);
 
                retcode = NO_ERROR;
@@ -3160,7 +3161,8 @@ int drbd_adm_delete_connection(struct sk_buff *skb, struct genl_info *info)
 
        down_write(&drbd_cfg_rwsem);
        if (conn_lowest_minor(adm_ctx.tconn) < 0) {
-               list_del(&adm_ctx.tconn->all_tconn);
+               list_del_rcu(&adm_ctx.tconn->all_tconn);
+               synchronize_rcu();
                kref_put(&adm_ctx.tconn->kref, &conn_destroy);
 
                retcode = NO_ERROR;