RDS: Change send lock from a mutex to a spinlock
This change allows us to call rds_send_xmit() from a tasklet,
which is crucial to our new operating model.
* Change c_send_lock to a spinlock
* Update stats fields "sem_" to "_lock"
* Remove unneeded rds_conn_is_sending()
About locking between shutdown and send -- send checks if the
connection is up. Shutdown puts the connection into
DISCONNECTING. After this, all threads entering send will exit
immediately. However, a thread could be *in* send_xmit(), so
shutdown acquires the c_send_lock to ensure everyone is out
before proceeding with connection shutdown.
Signed-off-by: Andy Grover <andy.grover@oracle.com>
diff --git a/net/rds/rds.h b/net/rds/rds.h
index e81d7e4..c3a668b 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -91,7 +91,7 @@
struct rds_cong_map *c_lcong;
struct rds_cong_map *c_fcong;
- struct mutex c_send_lock; /* protect send ring */
+ spinlock_t c_send_lock; /* protect send ring */
struct rds_message *c_xmit_rm;
unsigned long c_xmit_sg;
unsigned int c_xmit_hdr_off;
@@ -548,8 +548,8 @@
uint64_t s_recv_ping;
uint64_t s_send_queue_empty;
uint64_t s_send_queue_full;
- uint64_t s_send_sem_contention;
- uint64_t s_send_sem_queue_raced;
+ uint64_t s_send_lock_contention;
+ uint64_t s_send_lock_queue_raced;
uint64_t s_send_immediate_retry;
uint64_t s_send_delayed_retry;
uint64_t s_send_drop_acked;