[PATCH 5/5] IB/hfi1: Fix improper uses of smp_mb__before_atomic()

Andrea Parri
2019-04-29T20:16:13Z

This barrier only applies to the read-modify-write operations; in
particular, it does not apply to the atomic_read() primitive.

Replace the barrier with an smp_mb().

Fixes: 856cc4c237add ("IB/hfi1: Add the capability for reserved operations")
Cc: stable@vger.kernel.org
Reported-by: "Paul E. McKenney" <paulmck@linux.ibm.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Dennis Dalessandro <dennis.dalessandro@intel.com>
Cc: Mike Marciniszyn <mike.marciniszyn@intel.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-rdma@vger.kernel.org
---
drivers/infiniband/sw/rdmavt/qp.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/sw/rdmavt/qp.c b/drivers/infiniband/sw/rdmavt/qp.c
index a34b9a2a32b60..b64fd151d31fb 100644
--- a/drivers/infiniband/sw/rdmavt/qp.c
+++ b/drivers/infiniband/sw/rdmavt/qp.c
@@ -1863,11 +1863,11 @@ static inline int rvt_qp_is_avail(
u32 reserved_used;

/* see rvt_qp_wqe_unreserve() */
- smp_mb__before_atomic();
+ smp_mb();
reserved_used = atomic_read(&qp->s_reserved_used);
if (unlikely(reserved_op)) {
/* see rvt_qp_wqe_unreserve() */
- smp_mb__before_atomic();
+ smp_mb();
if (reserved_used >= rdi->dparms.reserved_operations)
return -ENOMEM;
return 0;
@@ -1882,7 +1882,7 @@ static inline int rvt_qp_is_avail(
avail = slast - qp->s_head;

/* see rvt_qp_wqe_unreserve() */
- smp_mb__before_atomic();
+ smp_mb();
reserved_used = atomic_read(&qp->s_reserved_used);
avail = avail - 1 -
(rdi->dparms.reserved_operations - reserved_used);
--
2.7.4