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

[Andrea Parri]

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: sta...@vger.kernel.org
Reported-by: "Paul E. McKenney" <paul...@linux.ibm.com>
Reported-by: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Andrea Parri <andrea.pa...@amarulasolutions.com>
Cc: Dennis Dalessandro <dennis.dalessan...@intel.com>
Cc: Mike Marciniszyn <mike.marcinis...@intel.com>
Cc: Doug Ledford <dledf...@redhat.com>
Cc: Jason Gunthorpe <j...@ziepe.ca>
Cc: linux-r...@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