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Commit b668534c authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

bnx2: use READ_ONCE() instead of barrier() 



barrier() is a big hammer compared to READ_ONCE(),
and requires comments explaining what is protected.

READ_ONCE() is more precise and compiler should generate
better overall code.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d21dbdfe

drivers/net/ethernet/broadcom/bnx2.c

+5 −12
Original line number Diff line number Diff line
@@ -254,13 +254,10 @@ static inline u32 bnx2_tx_avail(struct bnx2 *bp, struct bnx2_tx_ring_info *txr) 
{

	u32 diff;



	/* Tell compiler to fetch tx_prod and tx_cons from memory. */

	barrier();



	/* The ring uses 256 indices for 255 entries, one of them

	 * needs to be skipped.

	 */

	diff = txr->tx_prod - txr->tx_cons;

	diff = READ_ONCE(txr->tx_prod) - READ_ONCE(txr->tx_cons);

	if (unlikely(diff >= BNX2_TX_DESC_CNT)) {

		diff &= 0xffff;

		if (diff == BNX2_TX_DESC_CNT)
@@ -2839,10 +2836,8 @@ bnx2_get_hw_tx_cons(struct bnx2_napi *bnapi) 
{

	u16 cons;



	/* Tell compiler that status block fields can change. */

	barrier();

	cons = *bnapi->hw_tx_cons_ptr;

	barrier();

	cons = READ_ONCE(*bnapi->hw_tx_cons_ptr);



	if (unlikely((cons & BNX2_MAX_TX_DESC_CNT) == BNX2_MAX_TX_DESC_CNT))

		cons++;

	return cons;
@@ -3141,10 +3136,8 @@ bnx2_get_hw_rx_cons(struct bnx2_napi *bnapi) 
{

	u16 cons;



	/* Tell compiler that status block fields can change. */

	barrier();

	cons = *bnapi->hw_rx_cons_ptr;

	barrier();

	cons = READ_ONCE(*bnapi->hw_rx_cons_ptr);



	if (unlikely((cons & BNX2_MAX_RX_DESC_CNT) == BNX2_MAX_RX_DESC_CNT))

		cons++;

	return cons;