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Commit 17a30a14 authored by Rasesh Mody's avatar Rasesh Mody Committed by David S. Miller
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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
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+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);