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authorRasesh Mody <rmody@brocade.com>2013-12-17 17:07:37 -0800
committerDavid S. Miller <davem@davemloft.net>2013-12-18 00:30:34 -0500
commit17a30a14db09dfe9d3302f8a2d50571b0d94b144 (patch)
treefaf3875c0892bd7e0caaa4dbfa1041f57dd99789 /drivers/net/ethernet/brocade
parent66f9513a1213dfc5332b9675d206d47763b81761 (diff)
downloadlinux-17a30a14db09dfe9d3302f8a2d50571b0d94b144.tar.bz2
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: Rasesh Mody <rmody@brocade.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/brocade')
-rw-r--r--drivers/net/ethernet/brocade/bna/bnad.c23
1 files changed, 22 insertions, 1 deletions
diff --git a/drivers/net/ethernet/brocade/bna/bnad.c b/drivers/net/ethernet/brocade/bna/bnad.c
index 3061dc5e7a64..7d818de66e53 100644
--- a/drivers/net/ethernet/brocade/bna/bnad.c
+++ b/drivers/net/ethernet/brocade/bna/bnad.c
@@ -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);