net: ethernet: enetc: do not always access skb_shared_info in the XDP path

Move XDP skb_shared_info structure initialization in from
enetc_map_rx_buff_to_xdp() to enetc_add_rx_buff_to_xdp() and do not always
access skb_shared_info in the xdp_buff/xdp_frame since it is located in a
different cacheline with respect to hard_start and data xdp pointers.
Rely on XDP_FLAGS_HAS_FRAGS flag to check if it really necessary to access
non-linear part of the xdp_buff/xdp_frame.

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
index 18a01f6..5ad0b25 100644 (file)
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c
@@ -1305,6 +1305,10 @@ static int enetc_xdp_frame_to_xdp_tx_swbd(struct enetc_bdr *tx_ring,
        xdp_tx_swbd->xdp_frame = NULL;
 
        n++;
+
+       if (!xdp_frame_has_frags(xdp_frame))
+               goto out;
+
        xdp_tx_swbd = &xdp_tx_arr[n];
 
        shinfo = xdp_get_shared_info_from_frame(xdp_frame);
@@ -1334,7 +1338,7 @@ static int enetc_xdp_frame_to_xdp_tx_swbd(struct enetc_bdr *tx_ring,
                n++;
                xdp_tx_swbd = &xdp_tx_arr[n];
        }
-
+out:
        xdp_tx_arr[n - 1].is_eof = true;
        xdp_tx_arr[n - 1].xdp_frame = xdp_frame;
 
@@ -1390,16 +1394,12 @@ static void enetc_map_rx_buff_to_xdp(struct enetc_bdr *rx_ring, int i,
 {
        struct enetc_rx_swbd *rx_swbd = enetc_get_rx_buff(rx_ring, i, size);
        void *hard_start = page_address(rx_swbd->page) + rx_swbd->page_offset;
-       struct skb_shared_info *shinfo;
 
        /* To be used for XDP_TX */
        rx_swbd->len = size;
 
        xdp_prepare_buff(xdp_buff, hard_start - rx_ring->buffer_offset,
                         rx_ring->buffer_offset, size, false);
-
-       shinfo = xdp_get_shared_info_from_buff(xdp_buff);
-       shinfo->nr_frags = 0;
 }
 
 static void enetc_add_rx_buff_to_xdp(struct enetc_bdr *rx_ring, int i,
@@ -1407,7 +1407,7 @@ static void enetc_add_rx_buff_to_xdp(struct enetc_bdr *rx_ring, int i,
 {
        struct skb_shared_info *shinfo = xdp_get_shared_info_from_buff(xdp_buff);
        struct enetc_rx_swbd *rx_swbd = enetc_get_rx_buff(rx_ring, i, size);
-       skb_frag_t *frag = &shinfo->frags[shinfo->nr_frags];
+       skb_frag_t *frag;
 
        /* To be used for XDP_TX */
        rx_swbd->len = size;
@@ -1415,6 +1415,7 @@ static void enetc_add_rx_buff_to_xdp(struct enetc_bdr *rx_ring, int i,
        if (!xdp_buff_has_frags(xdp_buff)) {
                xdp_buff_set_frags_flag(xdp_buff);
                shinfo->xdp_frags_size = size;
+               shinfo->nr_frags = 0;
        } else {
                shinfo->xdp_frags_size += size;
        }
@@ -1422,6 +1423,7 @@ static void enetc_add_rx_buff_to_xdp(struct enetc_bdr *rx_ring, int i,
        if (page_is_pfmemalloc(rx_swbd->page))
                xdp_buff_set_frag_pfmemalloc(xdp_buff);
 
+       frag = &shinfo->frags[shinfo->nr_frags];
        skb_frag_off_set(frag, rx_swbd->page_offset);
        skb_frag_size_set(frag, size);
        __skb_frag_set_page(frag, rx_swbd->page);