Commit cb7e125e authored Oct 09, 2017 by Paul E. McKenney

drivers/net/ethernet/qlogic/qed: Fix __qed_spq_block() ordering



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@linux.vnet.ibm.com>
Cc: Ariel Elior <Ariel.Elior@cavium.com>
Cc: <everest-linux-l2@cavium.com>
Cc: <netdev@vger.kernel.org>

parent a4bd78ed

drivers/net/ethernet/qlogic/qed/qed_spq.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -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;