RDMA/cma: Simplify locking needed for serialization of callbacks
The RDMA CM has some logic in place to make sure that callbacks on a
given CM ID are delivered to the consumer in a serialized manner.
Specifically it has code to protect against a device removal racing
with a running callback function.
This patch simplifies this logic by using a mutex per ID instead of a
wait queue and atomic variable. This means that cma_disable_remove()
now is more properly named to cma_disable_callback(), and
cma_enable_remove() can now be removed because it just would become a
trivial wrapper around mutex_unlock().
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 5fb506a..ae11d5c 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -130,8 +130,7 @@
struct completion comp;
atomic_t refcount;
- wait_queue_head_t wait_remove;
- atomic_t dev_remove;
+ struct mutex handler_mutex;
int backlog;
int timeout_ms;
@@ -355,26 +354,15 @@
complete(&id_priv->comp);
}
-static int cma_disable_remove(struct rdma_id_private *id_priv,
+static int cma_disable_callback(struct rdma_id_private *id_priv,
enum cma_state state)
{
- unsigned long flags;
- int ret;
-
- spin_lock_irqsave(&id_priv->lock, flags);
- if (id_priv->state == state) {
- atomic_inc(&id_priv->dev_remove);
- ret = 0;
- } else
- ret = -EINVAL;
- spin_unlock_irqrestore(&id_priv->lock, flags);
- return ret;
-}
-
-static void cma_enable_remove(struct rdma_id_private *id_priv)
-{
- if (atomic_dec_and_test(&id_priv->dev_remove))
- wake_up(&id_priv->wait_remove);
+ mutex_lock(&id_priv->handler_mutex);
+ if (id_priv->state != state) {
+ mutex_unlock(&id_priv->handler_mutex);
+ return -EINVAL;
+ }
+ return 0;
}
static int cma_has_cm_dev(struct rdma_id_private *id_priv)
@@ -399,8 +387,7 @@
mutex_init(&id_priv->qp_mutex);
init_completion(&id_priv->comp);
atomic_set(&id_priv->refcount, 1);
- init_waitqueue_head(&id_priv->wait_remove);
- atomic_set(&id_priv->dev_remove, 0);
+ mutex_init(&id_priv->handler_mutex);
INIT_LIST_HEAD(&id_priv->listen_list);
INIT_LIST_HEAD(&id_priv->mc_list);
get_random_bytes(&id_priv->seq_num, sizeof id_priv->seq_num);
@@ -927,7 +914,7 @@
struct rdma_cm_event event;
int ret = 0;
- if (cma_disable_remove(id_priv, CMA_CONNECT))
+ if (cma_disable_callback(id_priv, CMA_CONNECT))
return 0;
memset(&event, 0, sizeof event);
@@ -984,12 +971,12 @@
/* Destroy the CM ID by returning a non-zero value. */
id_priv->cm_id.ib = NULL;
cma_exch(id_priv, CMA_DESTROYING);
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
rdma_destroy_id(&id_priv->id);
return ret;
}
out:
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
return ret;
}
@@ -1101,7 +1088,7 @@
int offset, ret;
listen_id = cm_id->context;
- if (cma_disable_remove(listen_id, CMA_LISTEN))
+ if (cma_disable_callback(listen_id, CMA_LISTEN))
return -ECONNABORTED;
memset(&event, 0, sizeof event);
@@ -1122,7 +1109,7 @@
goto out;
}
- atomic_inc(&conn_id->dev_remove);
+ mutex_lock_nested(&conn_id->handler_mutex, SINGLE_DEPTH_NESTING);
mutex_lock(&lock);
ret = cma_acquire_dev(conn_id);
mutex_unlock(&lock);
@@ -1144,7 +1131,7 @@
!cma_is_ud_ps(conn_id->id.ps))
ib_send_cm_mra(cm_id, CMA_CM_MRA_SETTING, NULL, 0);
mutex_unlock(&lock);
- cma_enable_remove(conn_id);
+ mutex_unlock(&conn_id->handler_mutex);
goto out;
}
@@ -1153,11 +1140,11 @@
release_conn_id:
cma_exch(conn_id, CMA_DESTROYING);
- cma_enable_remove(conn_id);
+ mutex_unlock(&conn_id->handler_mutex);
rdma_destroy_id(&conn_id->id);
out:
- cma_enable_remove(listen_id);
+ mutex_unlock(&listen_id->handler_mutex);
return ret;
}
@@ -1223,7 +1210,7 @@
struct sockaddr_in *sin;
int ret = 0;
- if (cma_disable_remove(id_priv, CMA_CONNECT))
+ if (cma_disable_callback(id_priv, CMA_CONNECT))
return 0;
memset(&event, 0, sizeof event);
@@ -1267,12 +1254,12 @@
/* Destroy the CM ID by returning a non-zero value. */
id_priv->cm_id.iw = NULL;
cma_exch(id_priv, CMA_DESTROYING);
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
rdma_destroy_id(&id_priv->id);
return ret;
}
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
return ret;
}
@@ -1288,7 +1275,7 @@
struct ib_device_attr attr;
listen_id = cm_id->context;
- if (cma_disable_remove(listen_id, CMA_LISTEN))
+ if (cma_disable_callback(listen_id, CMA_LISTEN))
return -ECONNABORTED;
/* Create a new RDMA id for the new IW CM ID */
@@ -1300,19 +1287,19 @@
goto out;
}
conn_id = container_of(new_cm_id, struct rdma_id_private, id);
- atomic_inc(&conn_id->dev_remove);
+ mutex_lock_nested(&conn_id->handler_mutex, SINGLE_DEPTH_NESTING);
conn_id->state = CMA_CONNECT;
dev = ip_dev_find(&init_net, iw_event->local_addr.sin_addr.s_addr);
if (!dev) {
ret = -EADDRNOTAVAIL;
- cma_enable_remove(conn_id);
+ mutex_unlock(&conn_id->handler_mutex);
rdma_destroy_id(new_cm_id);
goto out;
}
ret = rdma_copy_addr(&conn_id->id.route.addr.dev_addr, dev, NULL);
if (ret) {
- cma_enable_remove(conn_id);
+ mutex_unlock(&conn_id->handler_mutex);
rdma_destroy_id(new_cm_id);
goto out;
}
@@ -1321,7 +1308,7 @@
ret = cma_acquire_dev(conn_id);
mutex_unlock(&lock);
if (ret) {
- cma_enable_remove(conn_id);
+ mutex_unlock(&conn_id->handler_mutex);
rdma_destroy_id(new_cm_id);
goto out;
}
@@ -1337,7 +1324,7 @@
ret = ib_query_device(conn_id->id.device, &attr);
if (ret) {
- cma_enable_remove(conn_id);
+ mutex_unlock(&conn_id->handler_mutex);
rdma_destroy_id(new_cm_id);
goto out;
}
@@ -1353,14 +1340,17 @@
/* User wants to destroy the CM ID */
conn_id->cm_id.iw = NULL;
cma_exch(conn_id, CMA_DESTROYING);
- cma_enable_remove(conn_id);
+ mutex_unlock(&conn_id->handler_mutex);
rdma_destroy_id(&conn_id->id);
+ goto out;
}
+ mutex_unlock(&conn_id->handler_mutex);
+
out:
if (dev)
dev_put(dev);
- cma_enable_remove(listen_id);
+ mutex_unlock(&listen_id->handler_mutex);
return ret;
}
@@ -1592,7 +1582,7 @@
struct rdma_id_private *id_priv = work->id;
int destroy = 0;
- atomic_inc(&id_priv->dev_remove);
+ mutex_lock(&id_priv->handler_mutex);
if (!cma_comp_exch(id_priv, work->old_state, work->new_state))
goto out;
@@ -1601,7 +1591,7 @@
destroy = 1;
}
out:
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
cma_deref_id(id_priv);
if (destroy)
rdma_destroy_id(&id_priv->id);
@@ -1764,7 +1754,7 @@
struct rdma_cm_event event;
memset(&event, 0, sizeof event);
- atomic_inc(&id_priv->dev_remove);
+ mutex_lock(&id_priv->handler_mutex);
/*
* Grab mutex to block rdma_destroy_id() from removing the device while
@@ -1793,13 +1783,13 @@
if (id_priv->id.event_handler(&id_priv->id, &event)) {
cma_exch(id_priv, CMA_DESTROYING);
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
cma_deref_id(id_priv);
rdma_destroy_id(&id_priv->id);
return;
}
out:
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
cma_deref_id(id_priv);
}
@@ -2126,7 +2116,7 @@
struct ib_cm_sidr_rep_event_param *rep = &ib_event->param.sidr_rep_rcvd;
int ret = 0;
- if (cma_disable_remove(id_priv, CMA_CONNECT))
+ if (cma_disable_callback(id_priv, CMA_CONNECT))
return 0;
memset(&event, 0, sizeof event);
@@ -2167,12 +2157,12 @@
/* Destroy the CM ID by returning a non-zero value. */
id_priv->cm_id.ib = NULL;
cma_exch(id_priv, CMA_DESTROYING);
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
rdma_destroy_id(&id_priv->id);
return ret;
}
out:
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
return ret;
}
@@ -2570,8 +2560,8 @@
int ret;
id_priv = mc->id_priv;
- if (cma_disable_remove(id_priv, CMA_ADDR_BOUND) &&
- cma_disable_remove(id_priv, CMA_ADDR_RESOLVED))
+ if (cma_disable_callback(id_priv, CMA_ADDR_BOUND) &&
+ cma_disable_callback(id_priv, CMA_ADDR_RESOLVED))
return 0;
mutex_lock(&id_priv->qp_mutex);
@@ -2596,12 +2586,12 @@
ret = id_priv->id.event_handler(&id_priv->id, &event);
if (ret) {
cma_exch(id_priv, CMA_DESTROYING);
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
rdma_destroy_id(&id_priv->id);
return 0;
}
- cma_enable_remove(id_priv);
+ mutex_unlock(&id_priv->handler_mutex);
return 0;
}
@@ -2760,6 +2750,7 @@
{
struct rdma_cm_event event;
enum cma_state state;
+ int ret = 0;
/* Record that we want to remove the device */
state = cma_exch(id_priv, CMA_DEVICE_REMOVAL);
@@ -2767,15 +2758,18 @@
return 0;
cma_cancel_operation(id_priv, state);
- wait_event(id_priv->wait_remove, !atomic_read(&id_priv->dev_remove));
+ mutex_lock(&id_priv->handler_mutex);
/* Check for destruction from another callback. */
if (!cma_comp(id_priv, CMA_DEVICE_REMOVAL))
- return 0;
+ goto out;
memset(&event, 0, sizeof event);
event.event = RDMA_CM_EVENT_DEVICE_REMOVAL;
- return id_priv->id.event_handler(&id_priv->id, &event);
+ ret = id_priv->id.event_handler(&id_priv->id, &event);
+out:
+ mutex_unlock(&id_priv->handler_mutex);
+ return ret;
}
static void cma_process_remove(struct cma_device *cma_dev)