IB/ehca: Wait for async events to finish before destroying QP

This is necessary because, in a multicore environment, a race between
uverbs async handler and destroy QP could occur.

Signed-off-by: Stefan Roscher <stefan.roscher at de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

3 files changed, 11 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/ehca/ehca_classes.h b/drivers/infiniband/hw/ehca/ehca_classes.h
index 00bab60f6de4..1e9e99a13933 100644
--- a/drivers/infiniband/hw/ehca/ehca_classes.h
+++ b/drivers/infiniband/hw/ehca/ehca_classes.h
@@ -192,6 +192,8 @@ struct ehca_qp {
         int mtu_shift;
         u32 message_count;
         u32 packet_count;
+        atomic_t nr_events; /* events seen */
+        wait_queue_head_t wait_completion;
 };
 
 #define IS_SRQ(qp) (qp->ext_type == EQPT_SRQ)
diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c
index ca5eb0cb628c..ce1ab0571be3 100644
--- a/drivers/infiniband/hw/ehca/ehca_irq.c
+++ b/drivers/infiniband/hw/ehca/ehca_irq.c
@@ -204,6 +204,8 @@ static void qp_event_callback(struct ehca_shca *shca, u64 eqe,
 
         read_lock(&ehca_qp_idr_lock);
         qp = idr_find(&ehca_qp_idr, token);
+        if (qp)
+                atomic_inc(&qp->nr_events);
         read_unlock(&ehca_qp_idr_lock);
 
         if (!qp)
@@ -223,6 +225,8 @@ static void qp_event_callback(struct ehca_shca *shca, u64 eqe,
         if (fatal && qp->ext_type == EQPT_SRQBASE)
                 dispatch_qp_event(shca, qp, IB_EVENT_QP_LAST_WQE_REACHED);
 
+        if (atomic_dec_and_test(&qp->nr_events))
+                wake_up(&qp->wait_completion);
         return;
 }
 
diff --git a/drivers/infiniband/hw/ehca/ehca_qp.c b/drivers/infiniband/hw/ehca/ehca_qp.c
index 18fba92fa7ae..3f59587338ea 100644
--- a/drivers/infiniband/hw/ehca/ehca_qp.c
+++ b/drivers/infiniband/hw/ehca/ehca_qp.c
@@ -566,6 +566,8 @@ static struct ehca_qp *internal_create_qp(
                 return ERR_PTR(-ENOMEM);
         }
 
+        atomic_set(&my_qp->nr_events, 0);
+        init_waitqueue_head(&my_qp->wait_completion);
         spin_lock_init(&my_qp->spinlock_s);
         spin_lock_init(&my_qp->spinlock_r);
         my_qp->qp_type = qp_type;
@@ -1934,6 +1936,9 @@ static int internal_destroy_qp(struct ib_device *dev, struct ehca_qp *my_qp,
         idr_remove(&ehca_qp_idr, my_qp->token);
         write_unlock_irqrestore(&ehca_qp_idr_lock, flags);
 
+        /* now wait until all pending events have completed */
+        wait_event(my_qp->wait_completion, !atomic_read(&my_qp->nr_events));
+
         h_ret = hipz_h_destroy_qp(shca->ipz_hca_handle, my_qp);
         if (h_ret != H_SUCCESS) {
                 ehca_err(dev, "hipz_h_destroy_qp() failed h_ret=%li "