# \[PATCH net-next 4/9\] net: enetc: clean the TX software BD on the TX confirmation path - From: Vladimir Oltean \ - Date: 2021-03-31 20:10:23 - List: netdev - Page: https://ratatoskr.run/netdev/2021/03/7764297 - Thread: https://ratatoskr.run/netdev/2021/03/7764295/t.md ```text From: Vladimir Oltean With the future introduction of some new fields into enetc_tx_swbd such as is_xdp_tx, is_xdp_redirect etc, we need not only to set these bits to true from the XDP_TX/XDP_REDIRECT code path, but also to false from the old code paths. This is because TX software buffer descriptors are kept in a ring that is shadow of the hardware TX ring, so these structures keep getting reused, and there is always the possibility that when a software BD is reused (after we ran a full circle through the TX ring), the old user of the tx_swbd had set is_xdp_tx = true, and now we are sending a regular skb, which would need to set is_xdp_tx = false. To be minimally invasive to the old code paths, let's just scrub the software TX BD in the TX confirmation path (enetc_clean_tx_ring), once we know that nobody uses this software TX BD (tx_ring->next_to_clean hasn't yet been updated, and the TX paths check enetc_bd_unused which tells them if there's any more space in the TX ring for a new enqueue). Signed-off-by: Vladimir Oltean --- drivers/net/ethernet/freescale/enetc/enetc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c index 37d2d142a744..ade05518b496 100644 --- a/drivers/net/ethernet/freescale/enetc/enetc.c +++ b/drivers/net/ethernet/freescale/enetc/enetc.c @@ -344,6 +344,10 @@ static bool enetc_clean_tx_ring(struct enetc_bdr *tx_ring, int napi_budget) } tx_byte_cnt += tx_swbd->len; + /* Scrub the swbd here so we don't have to do that + * when we reuse it during xmit + */ + memset(tx_swbd, 0, sizeof(*tx_swbd)); bds_to_clean--; tx_swbd++; -- 2.25.1 ```