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Subject[PATCH 3.16 089/305] IB/cm: Fix sleeping while spin lock is held
3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Parav Pandit <parav@mellanox.com>

commit 33f93e1ebcf5acfaef06cda2d3e373730519e33e upstream.

In case of LAP are used for RoCE, it can lead to a problem of sleeping a
context while spin lock is held in below flow.

cm_lap_handler
->spin_lock
-> <..switch_case..>
-> cm_init_av_for_response
-> ib_init_ah_from_wc
-> rdma_addr_find_l2_eth_by_grh
wait_for_completion()

Therefore ah attribute initialization is done for incoming lap requests
outside of the lock context.

Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/infiniband/core/cm.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -2770,6 +2770,12 @@ static int cm_lap_handler(struct cm_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;
param->alternate_path = &work->path[0];
cm_format_path_from_lap(cm_id_priv, param->alternate_path, lap_msg);
@@ -2809,11 +2815,6 @@ static int cm_lap_handler(struct cm_work

cm_id_priv->id.lap_state = IB_CM_LAP_RCVD;
cm_id_priv->tid = lap_msg->hdr.tid;
- 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 unlock;
cm_init_av_by_path(param->alternate_path, &cm_id_priv->alt_av,
cm_id_priv);
ret = atomic_inc_and_test(&cm_id_priv->work_count);
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