@@ -183,15 +183,14 @@ static void free_cm_id(struct iwcm_id_private *cm_id_priv)
/*
* Release a reference on cm_id. If the last reference is being
- * released, enable the waiting thread (in iw_destroy_cm_id) to
- * get woken up, and return 1 if a thread is already waiting.
+ * released, free the cm_id and return 1.
*/
static int iwcm_deref_id(struct iwcm_id_private *cm_id_priv)
{
BUG_ON(atomic_read(&cm_id_priv->refcount)==0);
if (atomic_dec_and_test(&cm_id_priv->refcount)) {
BUG_ON(!list_empty(&cm_id_priv->work_list));
- complete(&cm_id_priv->destroy_comp);
+ free_cm_id(cm_id_priv);
return 1;
}
@@ -208,19 +207,10 @@ static void add_ref(struct iw_cm_id *cm_id)
static void rem_ref(struct iw_cm_id *cm_id)
{
struct iwcm_id_private *cm_id_priv;
- int cb_destroy;
cm_id_priv = container_of(cm_id, struct iwcm_id_private, id);
- /*
- * Test bit before deref in case the cm_id gets freed on another
- * thread.
- */
- cb_destroy = test_bit(IWCM_F_CALLBACK_DESTROY, &cm_id_priv->flags);
- if (iwcm_deref_id(cm_id_priv) && cb_destroy) {
- BUG_ON(!list_empty(&cm_id_priv->work_list));
- free_cm_id(cm_id_priv);
- }
+ (void)iwcm_deref_id(cm_id_priv);
}
static int cm_event_handler(struct iw_cm_id *cm_id, struct iw_cm_event *event);
@@ -370,6 +360,12 @@ static void destroy_cm_id(struct iw_cm_id *cm_id)
wait_event(cm_id_priv->connect_wait,
!test_bit(IWCM_F_CONNECT_WAIT, &cm_id_priv->flags));
+ /*
+ * Since we're deleting the cm_id, drop any events that
+ * might arrive before the last dereference.
+ */
+ set_bit(IWCM_F_DROP_EVENTS, &cm_id_priv->flags);
+
spin_lock_irqsave(&cm_id_priv->lock, flags);
switch (cm_id_priv->state) {
case IW_CM_STATE_LISTEN:
@@ -433,13 +429,7 @@ void iw_destroy_cm_id(struct iw_cm_id *cm_id)
struct iwcm_id_private *cm_id_priv;
cm_id_priv = container_of(cm_id, struct iwcm_id_private, id);
- BUG_ON(test_bit(IWCM_F_CALLBACK_DESTROY, &cm_id_priv->flags));
-
destroy_cm_id(cm_id);
-
- wait_for_completion(&cm_id_priv->destroy_comp);
-
- free_cm_id(cm_id_priv);
}
EXPORT_SYMBOL(iw_destroy_cm_id);
@@ -809,10 +799,7 @@ static void cm_conn_req_handler(struct iwcm_id_private *listen_id_priv,
ret = cm_id->cm_handler(cm_id, iw_event);
if (ret) {
iw_cm_reject(cm_id, NULL, 0);
- set_bit(IWCM_F_CALLBACK_DESTROY, &cm_id_priv->flags);
- destroy_cm_id(cm_id);
- if (atomic_read(&cm_id_priv->refcount)==0)
- free_cm_id(cm_id_priv);
+ iw_destroy_cm_id(cm_id);
}
out:
@@ -1000,7 +987,6 @@ static void cm_work_handler(struct work_struct *_work)
unsigned long flags;
int empty;
int ret = 0;
- int destroy_id;
spin_lock_irqsave(&cm_id_priv->lock, flags);
empty = list_empty(&cm_id_priv->work_list);
@@ -1013,20 +999,14 @@ static void cm_work_handler(struct work_struct *_work)
put_work(work);
spin_unlock_irqrestore(&cm_id_priv->lock, flags);
- ret = process_event(cm_id_priv, &levent);
- if (ret) {
- set_bit(IWCM_F_CALLBACK_DESTROY, &cm_id_priv->flags);
- destroy_cm_id(&cm_id_priv->id);
- }
- BUG_ON(atomic_read(&cm_id_priv->refcount)==0);
- destroy_id = test_bit(IWCM_F_CALLBACK_DESTROY, &cm_id_priv->flags);
- if (iwcm_deref_id(cm_id_priv)) {
- if (destroy_id) {
- BUG_ON(!list_empty(&cm_id_priv->work_list));
- free_cm_id(cm_id_priv);
- }
+ if (!test_bit(IWCM_F_DROP_EVENTS, &cm_id_priv->flags)) {
+ ret = process_event(cm_id_priv, &levent);
+ if (ret)
+ destroy_cm_id(&cm_id_priv->id);
+ } else
+ pr_debug("dropping event %d\n", levent.event);
+ if (iwcm_deref_id(cm_id_priv))
return;
- }
if (empty)
return;
spin_lock_irqsave(&cm_id_priv->lock, flags);
@@ -56,7 +56,7 @@ struct iwcm_id_private {
struct list_head work_free_list;
};
-#define IWCM_F_CALLBACK_DESTROY 1
+#define IWCM_F_DROP_EVENTS 1
#define IWCM_F_CONNECT_WAIT 2
#endif /* IWCM_H */
Remove the complicated logic to free the iw_cm_id inside iw_cm event handlers vs when an application thread destroys the cm_id. Also remove the block in iw_destroy_cm_id() to block the application until all references are removed. This block can cause a deadlock when disconnecting or destroying cm_ids inside an rdma_cm event handler. Simply allowing the last deref of the iw_cm_id to free the memory is cleaner and avoids this potential deadlock. Also a flag is added, IW_CM_DROP_EVENTS, that is set when the cm_id is marked for destruction. If any events are pending on this iw_cm_id, then as they are processed they will be dropped vs posted upstream if IW_CM_DROP_EVENTS is set. Signed-off-by: Steve Wise <swise@opengridcomputing.com> --- drivers/infiniband/core/iwcm.c | 54 +++++++++++++----------------------------- drivers/infiniband/core/iwcm.h | 2 +- 2 files changed, 18 insertions(+), 38 deletions(-)