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    Subject[PATCH 4.9 129/223] bnx2x: Prevent load reordering in tx completion processing
    Date
    From: Brian King <brking@linux.vnet.ibm.com>

    [ Upstream commit ea811b795df24644a8eb760b493c43fba4450677 ]

    This patch fixes an issue seen on Power systems with bnx2x which results
    in the skb is NULL WARN_ON in bnx2x_free_tx_pkt firing due to the skb
    pointer getting loaded in bnx2x_free_tx_pkt prior to the hw_cons
    load in bnx2x_tx_int. Adding a read memory barrier resolves the issue.

    Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c | 3 +++
    1 file changed, 3 insertions(+)

    --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
    +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
    @@ -286,6 +286,9 @@ int bnx2x_tx_int(struct bnx2x *bp, struc
    hw_cons = le16_to_cpu(*txdata->tx_cons_sb);
    sw_cons = txdata->tx_pkt_cons;

    + /* Ensure subsequent loads occur after hw_cons */
    + smp_rmb();
    +
    while (sw_cons != hw_cons) {
    u16 pkt_cons;


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