cxgb4: Use ACCES_ONCE macro to read queue's consumer index

Use helper macro ACCESS_ONCE() to load from the SGE status page
to prevent the compiler loading multiple times.

Based on original work by Mike Werner <werner@chelsio.com>

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/chelsio/cxgb4/sge.c b/drivers/net/ethernet/chelsio/cxgb4/sge.c
index 48d8fbb1c2200f0f2c4a4f7a6935a7ccddf3c7a2..1076c35a8bfd1ae07b74b54a47dbfa228137a56a 100644 (file)
--- a/drivers/net/ethernet/chelsio/cxgb4/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/sge.c
@@ -406,7 +406,7 @@ static void free_tx_desc(struct adapter *adap, struct sge_txq *q,
  */
 static inline int reclaimable(const struct sge_txq *q)
 {
-       int hw_cidx = ntohs(q->stat->cidx);
+       int hw_cidx = ntohs(ACCESS_ONCE(q->stat->cidx));
        hw_cidx -= q->cidx;
        return hw_cidx < 0 ? hw_cidx + q->size : hw_cidx;
 }
@@ -1320,7 +1320,7 @@ out_free: dev_kfree_skb_any(skb);
  */
 static inline void reclaim_completed_tx_imm(struct sge_txq *q)
 {
-       int hw_cidx = ntohs(q->stat->cidx);
+       int hw_cidx = ntohs(ACCESS_ONCE(q->stat->cidx));
        int reclaim = hw_cidx - q->cidx;
 
        if (reclaim < 0)