[PATCH for-rc] RDMA/rxe: Fix QP cleanup flow

[Kamal Heib <kamalheib1@gmail.com>]

Avoid releasing the socket associated with each QP in rxe_qp_cleanup()
which can sleep and move it to rxe_destroy_qp() instead, after doing
this there is no need for the execute_work that used to avoid calling
rxe_qp_cleanup() directly. also check that the socket is valid in
rxe_skb_tx_dtor() to avoid use-after-free.

Fixes: 8700e3e7c485 ("Soft RoCE driver")
Fixes: bb3ffb7ad48a ("RDMA/rxe: Fix rxe_qp_cleanup()")
Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
---
 drivers/infiniband/sw/rxe/rxe_net.c   | 14 ++++++++++++--
 drivers/infiniband/sw/rxe/rxe_qp.c    | 22 ++++++----------------
 drivers/infiniband/sw/rxe/rxe_verbs.h |  3 ---
 3 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_net.c b/drivers/infiniband/sw/rxe/rxe_net.c
index 312c2fc961c0..298ccd3fd3e2 100644
--- a/drivers/infiniband/sw/rxe/rxe_net.c
+++ b/drivers/infiniband/sw/rxe/rxe_net.c
@@ -411,8 +411,18 @@ int rxe_prepare(struct rxe_pkt_info *pkt, struct sk_buff *skb, u32 *crc)
 static void rxe_skb_tx_dtor(struct sk_buff *skb)
 {
 	struct sock *sk = skb->sk;
-	struct rxe_qp *qp = sk->sk_user_data;
-	int skb_out = atomic_dec_return(&qp->skb_out);
+	struct rxe_qp *qp;
+	int skb_out;
+
+	if (!sk)
+		return;
+
+	qp = sk->sk_user_data;
+
+	if (!qp)
+		return;
+
+	skb_out = atomic_dec_return(&qp->skb_out);
 
 	if (unlikely(qp->need_req_skb &&
 		     skb_out < RXE_INFLIGHT_SKBS_PER_QP_LOW))
diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c b/drivers/infiniband/sw/rxe/rxe_qp.c
index 6c11c3aeeca6..89dac6c1111c 100644
--- a/drivers/infiniband/sw/rxe/rxe_qp.c
+++ b/drivers/infiniband/sw/rxe/rxe_qp.c
@@ -787,6 +787,7 @@ void rxe_qp_destroy(struct rxe_qp *qp)
 	if (qp_type(qp) == IB_QPT_RC) {
 		del_timer_sync(&qp->retrans_timer);
 		del_timer_sync(&qp->rnr_nak_timer);
+		sk_dst_reset(qp->sk->sk);
 	}
 
 	rxe_cleanup_task(&qp->req.task);
@@ -798,12 +799,15 @@ void rxe_qp_destroy(struct rxe_qp *qp)
 		__rxe_do_task(&qp->comp.task);
 		__rxe_do_task(&qp->req.task);
 	}
+
+	kernel_sock_shutdown(qp->sk, SHUT_RDWR);
+	sock_release(qp->sk);
 }
 
 /* called when the last reference to the qp is dropped */
-static void rxe_qp_do_cleanup(struct work_struct *work)
+void rxe_qp_cleanup(struct rxe_pool_entry *arg)
 {
-	struct rxe_qp *qp = container_of(work, typeof(*qp), cleanup_work.work);
+	struct rxe_qp *qp = container_of(arg, typeof(*qp), pelem);
 
 	rxe_drop_all_mcast_groups(qp);
 
@@ -828,19 +832,5 @@ static void rxe_qp_do_cleanup(struct work_struct *work)
 		qp->resp.mr = NULL;
 	}
 
-	if (qp_type(qp) == IB_QPT_RC)
-		sk_dst_reset(qp->sk->sk);
-
 	free_rd_atomic_resources(qp);
-
-	kernel_sock_shutdown(qp->sk, SHUT_RDWR);
-	sock_release(qp->sk);
-}
-
-/* called when the last reference to the qp is dropped */
-void rxe_qp_cleanup(struct rxe_pool_entry *arg)
-{
-	struct rxe_qp *qp = container_of(arg, typeof(*qp), pelem);
-
-	execute_in_process_context(rxe_qp_do_cleanup, &qp->cleanup_work);
 }
diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h
index 92de39c4a7c1..339debaf095f 100644
--- a/drivers/infiniband/sw/rxe/rxe_verbs.h
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.h
@@ -35,7 +35,6 @@
 #define RXE_VERBS_H
 
 #include <linux/interrupt.h>
-#include <linux/workqueue.h>
 #include <rdma/rdma_user_rxe.h>
 #include "rxe_pool.h"
 #include "rxe_task.h"
@@ -285,8 +284,6 @@ struct rxe_qp {
 	struct timer_list rnr_nak_timer;
 
 	spinlock_t		state_lock; /* guard requester and completer */
-
-	struct execute_work	cleanup_work;
 };
 
 enum rxe_mem_state {
-- 
2.25.4