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Commit 17a30a14 authored by Rasesh Mody's avatar Rasesh Mody Committed by David S. Miller
Browse files

bna: CQ Read Fix 



Valid bit check for completion needs read fence, so that it does not get
reordered with other loads.

Signed-off-by: default avatarRasesh Mody <rmody@brocade.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 66f9513a

drivers/net/ethernet/brocade/bna/bnad.c

+22 −1
Original line number Diff line number Diff line
@@ -601,7 +601,18 @@ bnad_cq_process(struct bnad *bnad, struct bna_ccb *ccb, int budget) 
	cq = ccb->sw_q;

	cmpl = &cq[ccb->producer_index];



	while (cmpl->valid && (packets < budget)) {

	while (packets < budget) {

		if (!cmpl->valid)

			break;

		/* The 'valid' field is set by the adapter, only after writing

		 * the other fields of completion entry. Hence, do not load

		 * other fields of completion entry *before* the 'valid' is

		 * loaded. Adding the rmb() here prevents the compiler and/or

		 * CPU from reordering the reads which would potentially result

		 * in reading stale values in completion entry.

		 */

		rmb();



		BNA_UPDATE_PKT_CNT(pkt_rt, ntohs(cmpl->length));



		if (bna_is_small_rxq(cmpl->rxq_id))
@@ -641,6 +652,16 @@ bnad_cq_process(struct bnad *bnad, struct bna_ccb *ccb, int budget) 


				if (!next_cmpl->valid)

					break;

				/* The 'valid' field is set by the adapter, only

				 * after writing the other fields of completion

				 * entry. Hence, do not load other fields of

				 * completion entry *before* the 'valid' is

				 * loaded. Adding the rmb() here prevents the

				 * compiler and/or CPU from reordering the reads

				 * which would potentially result in reading

				 * stale values in completion entry.

				 */

				rmb();



				len = ntohs(next_cmpl->length);

				flags = ntohl(next_cmpl->flags);