From ebb90986e183296086b5d6678a838f125d743982 Mon Sep 17 00:00:00 2001 From: Steve Wise Date: Thu, 15 Feb 2007 08:09:36 -0600 Subject: [PATCH] RDMA/iwcm: iw_cm_id destruction race fixes iwcm iw_cm_id destruction race condition fixes: - iwcm_deref_id() always wakes up if there's another reference. - clean up race condition in cm_work_handler(). - create static void free_cm_id() which deallocs the work entries and then kfrees the cm_id memory. This reduces code replication. - rem_ref() if this is the last reference -and- the IWCM owns freeing the cm_id, then free it. Signed-off-by: Steve Wise Signed-off-by: Tom Tucker Acked-by: Krishna Kumar Signed-off-by: Roland Dreier --- drivers/infiniband/core/iwcm.c | 47 ++++++++++++++++++---------------- 1 file changed, 25 insertions(+), 22 deletions(-) diff --git a/drivers/infiniband/core/iwcm.c b/drivers/infiniband/core/iwcm.c index 1039ad57d53b..891d1fa7b2eb 100644 --- a/drivers/infiniband/core/iwcm.c +++ b/drivers/infiniband/core/iwcm.c @@ -146,6 +146,12 @@ static int copy_private_data(struct iw_cm_event *event) return 0; } +static void free_cm_id(struct iwcm_id_private *cm_id_priv) +{ + dealloc_work_entries(cm_id_priv); + kfree(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 @@ -153,21 +159,14 @@ static int copy_private_data(struct iw_cm_event *event) */ static int iwcm_deref_id(struct iwcm_id_private *cm_id_priv) { - int ret = 0; - 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)); - if (waitqueue_active(&cm_id_priv->destroy_comp.wait)) { - BUG_ON(cm_id_priv->state != IW_CM_STATE_DESTROYING); - BUG_ON(test_bit(IWCM_F_CALLBACK_DESTROY, - &cm_id_priv->flags)); - ret = 1; - } complete(&cm_id_priv->destroy_comp); + return 1; } - return ret; + return 0; } static void add_ref(struct iw_cm_id *cm_id) @@ -181,7 +180,11 @@ static void rem_ref(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); - iwcm_deref_id(cm_id_priv); + if (iwcm_deref_id(cm_id_priv) && + test_bit(IWCM_F_CALLBACK_DESTROY, &cm_id_priv->flags)) { + BUG_ON(!list_empty(&cm_id_priv->work_list)); + free_cm_id(cm_id_priv); + } } static int cm_event_handler(struct iw_cm_id *cm_id, struct iw_cm_event *event); @@ -355,7 +358,9 @@ static void destroy_cm_id(struct iw_cm_id *cm_id) case IW_CM_STATE_CONN_RECV: /* * App called destroy before/without calling accept after - * receiving connection request event notification. + * receiving connection request event notification or + * returned non zero from the event callback function. + * In either case, must tell the provider to reject. */ cm_id_priv->state = IW_CM_STATE_DESTROYING; break; @@ -391,9 +396,7 @@ void iw_destroy_cm_id(struct iw_cm_id *cm_id) wait_for_completion(&cm_id_priv->destroy_comp); - dealloc_work_entries(cm_id_priv); - - kfree(cm_id_priv); + free_cm_id(cm_id_priv); } EXPORT_SYMBOL(iw_destroy_cm_id); @@ -647,10 +650,11 @@ static void cm_conn_req_handler(struct iwcm_id_private *listen_id_priv, /* Call the client CM handler */ 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) - kfree(cm_id); + free_cm_id(cm_id_priv); } out: @@ -854,13 +858,12 @@ static void cm_work_handler(struct work_struct *_work) destroy_cm_id(&cm_id_priv->id); } BUG_ON(atomic_read(&cm_id_priv->refcount)==0); - if (iwcm_deref_id(cm_id_priv)) - return; - - if (atomic_read(&cm_id_priv->refcount)==0 && - test_bit(IWCM_F_CALLBACK_DESTROY, &cm_id_priv->flags)) { - dealloc_work_entries(cm_id_priv); - kfree(cm_id_priv); + if (iwcm_deref_id(cm_id_priv)) { + if (test_bit(IWCM_F_CALLBACK_DESTROY, + &cm_id_priv->flags)) { + BUG_ON(!list_empty(&cm_id_priv->work_list)); + free_cm_id(cm_id_priv); + } return; } spin_lock_irqsave(&cm_id_priv->lock, flags); -- 2.20.1