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Subject[PATCH 02/12] drbd: Use RCU for the drbd_tconns list
Date
Preparing removal of drbd_cfg_rwsem

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
---
drivers/block/drbd/drbd_main.c | 7 ++++---
drivers/block/drbd/drbd_nl.c | 12 +++++++-----
2 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 9e4c487..c229448 100644
--- 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 3c55be5..49f3b8d 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -2719,7 +2719,7 @@ 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;
@@ -2737,8 +2737,8 @@ 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,
@@ -3176,7 +3176,8 @@ 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;
@@ -3206,7 +3207,8 @@ 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;
--
1.7.4.1


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