diff options
| author | Rasesh Mody | 2013-12-17 17:07:37 -0800 |
|---|---|---|
| committer | David S. Miller | 2013-12-18 00:30:34 -0500 |
| commit | 17a30a14db09dfe9d3302f8a2d50571b0d94b144 (patch) | |
| tree | faf3875c0892bd7e0caaa4dbfa1041f57dd99789 /drivers | |
| parent | 66f9513a1213dfc5332b9675d206d47763b81761 (diff) | |
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')
| -rw-r--r-- | drivers/net/ethernet/brocade/bna/bnad.c | 23 |
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); |