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authorAndy Grover <andy.grover@oracle.com>2009-07-17 17:13:36 +0400
committerDavid S. Miller <davem@davemloft.net>2009-07-20 19:03:17 +0400
commitcb24405e67e56cbef51b5e4d0bb0a0fde167261f (patch)
tree3c1ced0452f0d9c6086eb88ab74dfcadacf01851 /net/rds/connection.c
parented9e352a350ec85eb354046e0db6a86019620f53 (diff)
downloadlinux-cb24405e67e56cbef51b5e4d0bb0a0fde167261f.tar.xz
RDS: Refactor end of __conn_create for readability
Add a comment for what's going on. Remove negative logic. I find this much easier to understand quickly, although there are a few lines duplicated. Signed-off-by: Andy Grover <andy.grover@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds/connection.c')
-rw-r--r--net/rds/connection.c48
1 files changed, 31 insertions, 17 deletions
diff --git a/net/rds/connection.c b/net/rds/connection.c
index 605fe3f60de3..b420a20d84fd 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -126,7 +126,7 @@ static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
struct rds_transport *trans, gfp_t gfp,
int is_outgoing)
{
- struct rds_connection *conn, *tmp, *parent = NULL;
+ struct rds_connection *conn, *parent = NULL;
struct hlist_head *head = rds_conn_bucket(laddr, faddr);
unsigned long flags;
int ret;
@@ -210,26 +210,40 @@ static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
trans->t_name ? trans->t_name : "[unknown]",
is_outgoing ? "(outgoing)" : "");
+ /*
+ * Since we ran without holding the conn lock, someone could
+ * have created the same conn (either normal or passive) in the
+ * interim. We check while holding the lock. If we won, we complete
+ * init and return our conn. If we lost, we rollback and return the
+ * other one.
+ */
spin_lock_irqsave(&rds_conn_lock, flags);
- if (parent == NULL) {
- tmp = rds_conn_lookup(head, laddr, faddr, trans);
- if (tmp == NULL)
- hlist_add_head(&conn->c_hash_node, head);
- } else {
- tmp = parent->c_passive;
- if (!tmp)
+ if (parent) {
+ /* Creating passive conn */
+ if (parent->c_passive) {
+ trans->conn_free(conn->c_transport_data);
+ kmem_cache_free(rds_conn_slab, conn);
+ conn = parent->c_passive;
+ } else {
parent->c_passive = conn;
- }
-
- if (tmp) {
- trans->conn_free(conn->c_transport_data);
- kmem_cache_free(rds_conn_slab, conn);
- conn = tmp;
+ rds_cong_add_conn(conn);
+ rds_conn_count++;
+ }
} else {
- rds_cong_add_conn(conn);
- rds_conn_count++;
+ /* Creating normal conn */
+ struct rds_connection *found;
+
+ found = rds_conn_lookup(head, laddr, faddr, trans);
+ if (found) {
+ trans->conn_free(conn->c_transport_data);
+ kmem_cache_free(rds_conn_slab, conn);
+ conn = found;
+ } else {
+ hlist_add_head(&conn->c_hash_node, head);
+ rds_cong_add_conn(conn);
+ rds_conn_count++;
+ }
}
-
spin_unlock_irqrestore(&rds_conn_lock, flags);
out: