[PATCH tip/core/rcu 03/21] drivers/net/ethernet/qlogic/qed: Fix __qed_spq_block() ordering

From: Paul E. McKenney
Date: Fri Dec 01 2017 - 14:51:39 EST


The __qed_spq_block() function expects an smp_read_barrier_depends()
to order a prior READ_ONCE() against a later load that does not depend
on the prior READ_ONCE(), an expectation that can fail to be met.
This commit therefore replaces the READ_ONCE() with smp_load_acquire()
and removes the smp_read_barrier_depends().

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Ariel Elior <Ariel.Elior@xxxxxxxxxx>
Cc: <everest-linux-l2@xxxxxxxxxx>
Cc: <netdev@xxxxxxxxxxxxxxx>
---
drivers/net/ethernet/qlogic/qed/qed_spq.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_spq.c b/drivers/net/ethernet/qlogic/qed/qed_spq.c
index be48d9abd001..c1237ec58b6c 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_spq.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_spq.c
@@ -97,9 +97,7 @@ static int __qed_spq_block(struct qed_hwfn *p_hwfn,

while (iter_cnt--) {
/* Validate we receive completion update */
- if (READ_ONCE(comp_done->done) == 1) {
- /* Read updated FW return value */
- smp_read_barrier_depends();
+ if (smp_load_acquire(&comp_done->done) == 1) { /* ^^^ */
if (p_fw_ret)
*p_fw_ret = comp_done->fw_return_code;
return 0;
--
2.5.2