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Subject[PATCH 4.6 19/56] IB/hfi1: Fix deadlock with txreq allocation slow path
Date
4.6-stable review patch.  If anyone has any objections, please let me know.

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

From: Mike Marciniszyn <mike.marciniszyn@intel.com>

commit 2aee309d3e01447c55fdf89cef05a0e2be372655 upstream.

A failure in the get_txreq() inline will result in a
slow path retry using __get_txreq().

__get_txreq() attempts to procure the qp s_lock, which
is already held in all callers.

Fix by deleting the s_lock maintenance in __get_txreq()
and add sparse syntax hooks to future proof the code.

Cc: Stable <stable@vger.kernel.org> # 4.6+
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/staging/rdma/hfi1/verbs_txreq.c | 4 +---
drivers/staging/rdma/hfi1/verbs_txreq.h | 1 +
2 files changed, 2 insertions(+), 3 deletions(-)

--- a/drivers/staging/rdma/hfi1/verbs_txreq.c
+++ b/drivers/staging/rdma/hfi1/verbs_txreq.c
@@ -92,11 +92,10 @@ void hfi1_put_txreq(struct verbs_txreq *

struct verbs_txreq *__get_txreq(struct hfi1_ibdev *dev,
struct rvt_qp *qp)
+ __must_hold(&qp->s_lock)
{
struct verbs_txreq *tx = ERR_PTR(-EBUSY);
- unsigned long flags;

- spin_lock_irqsave(&qp->s_lock, flags);
write_seqlock(&dev->iowait_lock);
if (ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK) {
struct hfi1_qp_priv *priv;
@@ -116,7 +115,6 @@ struct verbs_txreq *__get_txreq(struct h
}
out:
write_sequnlock(&dev->iowait_lock);
- spin_unlock_irqrestore(&qp->s_lock, flags);
return tx;
}

--- a/drivers/staging/rdma/hfi1/verbs_txreq.h
+++ b/drivers/staging/rdma/hfi1/verbs_txreq.h
@@ -73,6 +73,7 @@ struct verbs_txreq *__get_txreq(struct h

static inline struct verbs_txreq *get_txreq(struct hfi1_ibdev *dev,
struct rvt_qp *qp)
+ __must_hold(&qp->slock)
{
struct verbs_txreq *tx;
struct hfi1_qp_priv *priv = qp->priv;

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