From: Jason Gunthorpe <jgg@xxxxxxxxxx>
The REQ flows are concerned that once the handler is called on the new
cm_id the ULP can choose to trigger a rdma_destroy_id() concurrently at
any time.
However, this is not true, while the ULP can call rdma_destroy_id(), it
immediately blocks on the handler_mutex which prevents anything harmful
from running concurrently.
Remove the confusing extra locking and refcounts and make the
handler_mutex protecting state during destroy more clear.
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
---
drivers/infiniband/core/cma.c | 31 ++++++-------------------------
1 file changed, 6 insertions(+), 25 deletions(-)
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 04151c301e85..11f43204fee7 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -1831,21 +1831,21 @@ static void cma_leave_mc_groups(struct rdma_id_private *id_priv)
void rdma_destroy_id(struct rdma_cm_id *id)
{
- struct rdma_id_private *id_priv;
+ struct rdma_id_private *id_priv =
+ container_of(id, struct rdma_id_private, id);
enum rdma_cm_state state;
- id_priv = container_of(id, struct rdma_id_private, id);
- trace_cm_id_destroy(id_priv);
- state = cma_exch(id_priv, RDMA_CM_DESTROYING);
- cma_cancel_operation(id_priv, state);
-
/*
* Wait for any active callback to finish. New callbacks will find
* the id_priv state set to destroying and abort.
*/
mutex_lock(&id_priv->handler_mutex);
+ trace_cm_id_destroy(id_priv);
+ state = cma_exch(id_priv, RDMA_CM_DESTROYING);
mutex_unlock(&id_priv->handler_mutex);
+ cma_cancel_operation(id_priv, state);
+
rdma_restrack_del(&id_priv->res);
if (id_priv->cma_dev) {
if (rdma_cap_ib_cm(id_priv->id.device, 1)) {
@@ -2205,19 +2205,9 @@ static int cma_ib_req_handler(struct ib_cm_id *cm_id,
cm_id->context = conn_id;
cm_id->cm_handler = cma_ib_handler;
- /*
- * Protect against the user destroying conn_id from another thread
- * until we're done accessing it.
- */
- cma_id_get(conn_id);
ret = cma_cm_event_handler(conn_id, &event);
if (ret)
goto err3;
- /*
- * Acquire mutex to prevent user executing rdma_destroy_id()
- * while we're accessing the cm_id.
- */
- mutex_lock(&lock);
if (cma_comp(conn_id, RDMA_CM_CONNECT) &&
(conn_id->id.qp_type != IB_QPT_UD)) {
trace_cm_send_mra(cm_id->context);
@@ -2226,13 +2216,11 @@ static int cma_ib_req_handler(struct ib_cm_id *cm_id,
mutex_unlock(&lock);
mutex_unlock(&conn_id->handler_mutex);
mutex_unlock(&listen_id->handler_mutex);
- cma_id_put(conn_id);
if (net_dev)
dev_put(net_dev);
return 0;
err3:
- cma_id_put(conn_id);
/* Destroy the CM ID by returning a non-zero value. */
conn_id->cm_id.ib = NULL;
err2:
@@ -2409,11 +2397,6 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id,
memcpy(cma_src_addr(conn_id), laddr, rdma_addr_size(laddr));
memcpy(cma_dst_addr(conn_id), raddr, rdma_addr_size(raddr));
- /*
- * Protect against the user destroying conn_id from another thread
- * until we're done accessing it.
- */
- cma_id_get(conn_id);
ret = cma_cm_event_handler(conn_id, &event);
if (ret) {
/* User wants to destroy the CM ID */
@@ -2421,13 +2404,11 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id,
cma_exch(conn_id, RDMA_CM_DESTROYING);
mutex_unlock(&conn_id->handler_mutex);
mutex_unlock(&listen_id->handler_mutex);
- cma_id_put(conn_id);
rdma_destroy_id(&conn_id->id);
return ret;
}
mutex_unlock(&conn_id->handler_mutex);
- cma_id_put(conn_id);
out:
mutex_unlock(&listen_id->handler_mutex);
--
2.26.2
