[PATCH 6.2 540/663] RDMA/rxe: Remove tasklet call from rxe_cq.c

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From: Bob Pearson <rpearsonhpe@xxxxxxxxx>

[ Upstream commit 78b26a335310a097d6b22581b706050db42f196c ]

Remove the tasklet call in rxe_cq.c and also the is_dying in the
cq struct. There is no reason for the rxe driver to defer the call
to the cq completion handler by scheduling a tasklet. rxe_cq_post()
is not called in a hard irq context.

The rxe driver currently is incorrect because the tasklet call is
made without protecting the cq pointer with a reference from having
the underlying memory freed before the deferred routine is called.
Executing the comp_handler inline fixes this problem.

Fixes: 8700e3e7c485 ("Soft RoCE driver")
Signed-off-by: Bob Pearson <rpearsonhpe@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230327215643.10410-1-rpearsonhpe@xxxxxxxxx
Acked-by: Zhu Yanjun <zyjzyj2000@xxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/infiniband/sw/rxe/rxe_cq.c    |   32 +++-----------------------------
 drivers/infiniband/sw/rxe/rxe_verbs.c |    2 --
 drivers/infiniband/sw/rxe/rxe_verbs.h |    2 --
 3 files changed, 3 insertions(+), 33 deletions(-)

--- a/drivers/infiniband/sw/rxe/rxe_cq.c
+++ b/drivers/infiniband/sw/rxe/rxe_cq.c
@@ -39,21 +39,6 @@ err1:
 	return -EINVAL;
 }
 
-static void rxe_send_complete(struct tasklet_struct *t)
-{
-	struct rxe_cq *cq = from_tasklet(cq, t, comp_task);
-	unsigned long flags;
-
-	spin_lock_irqsave(&cq->cq_lock, flags);
-	if (cq->is_dying) {
-		spin_unlock_irqrestore(&cq->cq_lock, flags);
-		return;
-	}
-	spin_unlock_irqrestore(&cq->cq_lock, flags);
-
-	cq->ibcq.comp_handler(&cq->ibcq, cq->ibcq.cq_context);
-}
-
 int rxe_cq_from_init(struct rxe_dev *rxe, struct rxe_cq *cq, int cqe,
 		     int comp_vector, struct ib_udata *udata,
 		     struct rxe_create_cq_resp __user *uresp)
@@ -79,10 +64,6 @@ int rxe_cq_from_init(struct rxe_dev *rxe
 
 	cq->is_user = uresp;
 
-	cq->is_dying = false;
-
-	tasklet_setup(&cq->comp_task, rxe_send_complete);
-
 	spin_lock_init(&cq->cq_lock);
 	cq->ibcq.cqe = cqe;
 	return 0;
@@ -103,6 +84,7 @@ int rxe_cq_resize_queue(struct rxe_cq *c
 	return err;
 }
 
+/* caller holds reference to cq */
 int rxe_cq_post(struct rxe_cq *cq, struct rxe_cqe *cqe, int solicited)
 {
 	struct ib_event ev;
@@ -135,21 +117,13 @@ int rxe_cq_post(struct rxe_cq *cq, struc
 	if ((cq->notify == IB_CQ_NEXT_COMP) ||
 	    (cq->notify == IB_CQ_SOLICITED && solicited)) {
 		cq->notify = 0;
-		tasklet_schedule(&cq->comp_task);
+
+		cq->ibcq.comp_handler(&cq->ibcq, cq->ibcq.cq_context);
 	}
 
 	return 0;
 }
 
-void rxe_cq_disable(struct rxe_cq *cq)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&cq->cq_lock, flags);
-	cq->is_dying = true;
-	spin_unlock_irqrestore(&cq->cq_lock, flags);
-}
-
 void rxe_cq_cleanup(struct rxe_pool_elem *elem)
 {
 	struct rxe_cq *cq = container_of(elem, typeof(*cq), elem);
--- a/drivers/infiniband/sw/rxe/rxe_verbs.c
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
@@ -786,8 +786,6 @@ static int rxe_destroy_cq(struct ib_cq *
 	if (atomic_read(&cq->num_wq))
 		return -EINVAL;
 
-	rxe_cq_disable(cq);
-
 	rxe_cleanup(cq);
 	return 0;
 }
--- a/drivers/infiniband/sw/rxe/rxe_verbs.h
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.h
@@ -63,9 +63,7 @@ struct rxe_cq {
 	struct rxe_queue	*queue;
 	spinlock_t		cq_lock;
 	u8			notify;
-	bool			is_dying;
 	bool			is_user;
-	struct tasklet_struct	comp_task;
 	atomic_t		num_wq;
 };
 





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