linux-kernel - [PATCH 3.16 089/305] IB/cm: Fix sleeping while spin lock is held

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Message-ID: <lsq.1549201508.589896719@decadent.org.uk>
Date:   Sun, 03 Feb 2019 14:45:08 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Leon Romanovsky" <leon@...nel.org>,
        "Jason Gunthorpe" <jgg@...lanox.com>,
        "Parav Pandit" <parav@...lanox.com>,
        "Daniel Jurgens" <danielj@...lanox.com>
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@...lanox.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@...lanox.com>
Reviewed-by: Daniel Jurgens <danielj@...lanox.com>
Signed-off-by: Leon Romanovsky <leon@...nel.org>
Signed-off-by: Jason Gunthorpe <jgg@...lanox.com>
Signed-off-by: Ben Hutchings <ben@...adent.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);