From: Parav Pandit <parav@xxxxxxxxxxxx>
AH attribute of the cm_id can be overwritten if LAP message is received
on CM request which is in progress. This bug got introduced to avoid
sleeping when spin lock is held as part of commit in Fixes tag.
Therefore validate the cm_id state first and continue to perform AV
ah_attr initialization outside of the non blocking context.
Fixes: 33f93e1ebcf5 ("IB/cm: Fix sleeping while spin lock is held")
Reviewed-by: Daniel Jurgens <danielj@xxxxxxxxxxxx>
Signed-off-by: Parav Pandit <parav@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
---
drivers/infiniband/core/cm.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
index c5cd1b3ffa54..c9b325040df3 100644
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -3168,12 +3168,6 @@ static int cm_lap_handler(struct cm_work *work)
if (!cm_id_priv)
return -EINVAL;
- ret = cm_init_av_for_response(work->port, work->mad_recv_wc->wc,
- work->mad_recv_wc->recv_buf.grh,
- &cm_id_priv->av);
- if (ret)
- goto deref;
-
param = &work->cm_event.param.lap_rcvd;
memset(&work->path[0], 0, sizeof(work->path[1]));
cm_path_set_rec_type(work->port->cm_dev->ib_device,
@@ -3218,10 +3212,24 @@ static int cm_lap_handler(struct cm_work *work)
goto unlock;
}
- cm_id_priv->id.lap_state = IB_CM_LAP_RCVD;
- cm_id_priv->tid = lap_msg->hdr.tid;
+ /* It is safe to release spin lock while working on AV
+ * initialization from path record.
+ * While AV initialization in progress, refcount is taken
+ * by cm_acquire_id() at the start, therefore it is safe to
+ * release spin lock and re-acquire before updating state.
+ */
+ spin_unlock_irq(&cm_id_priv->lock);
+ ret = cm_init_av_for_response(work->port, work->mad_recv_wc->wc,
+ work->mad_recv_wc->recv_buf.grh,
+ &cm_id_priv->av);
+ if (ret)
+ goto deref;
+
cm_init_av_by_path(param->alternate_path, &cm_id_priv->alt_av,
cm_id_priv);
+ spin_lock_irq(&cm_id_priv->lock);
+ cm_id_priv->id.lap_state = IB_CM_LAP_RCVD;
+ cm_id_priv->tid = lap_msg->hdr.tid;
ret = atomic_inc_and_test(&cm_id_priv->work_count);
if (!ret)
list_add_tail(&work->list, &cm_id_priv->work_list);
--
2.16.2
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