sfc: Include XDP packet headroom in buffer step size.

Correct a mismatch between rx_page_buf_step and the actual step size
used when filling buffer pages.

This patch fixes the page overrun that occured when the MTU was set to
anything bigger than 1692.

Fixes: 2e6b0faad9d7 ("sfc: allocate channels for XDP tx queues")
Signed-off-by: Charles McLachlan <cmclachlan@solarflare.com>
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c
index ef52b24ad9e72c8489e5108a8bc4ff4d4e3b9364..c29bf862a94c545082ab215543231310caf54989 100644 (file)
--- a/drivers/net/ethernet/sfc/rx.c
+++ b/drivers/net/ethernet/sfc/rx.c
@@ -96,11 +96,12 @@ static inline void efx_sync_rx_buffer(struct efx_nic *efx,
 
 void efx_rx_config_page_split(struct efx_nic *efx)
 {
-       efx->rx_page_buf_step = ALIGN(efx->rx_dma_len + efx->rx_ip_align,
+       efx->rx_page_buf_step = ALIGN(efx->rx_dma_len + efx->rx_ip_align +
+                                     XDP_PACKET_HEADROOM,
                                      EFX_RX_BUF_ALIGNMENT);
        efx->rx_bufs_per_page = efx->rx_buffer_order ? 1 :
                ((PAGE_SIZE - sizeof(struct efx_rx_page_state)) /
-               (efx->rx_page_buf_step + XDP_PACKET_HEADROOM));
+               efx->rx_page_buf_step);
        efx->rx_buffer_truesize = (PAGE_SIZE << efx->rx_buffer_order) /
                efx->rx_bufs_per_page;
        efx->rx_pages_per_batch = DIV_ROUND_UP(EFX_RX_PREFERRED_BATCH,
@@ -190,14 +191,13 @@ static int efx_init_rx_buffers(struct efx_rx_queue *rx_queue, bool atomic)
                page_offset = sizeof(struct efx_rx_page_state);
 
                do {
-                       page_offset += XDP_PACKET_HEADROOM;
-                       dma_addr += XDP_PACKET_HEADROOM;
-
                        index = rx_queue->added_count & rx_queue->ptr_mask;
                        rx_buf = efx_rx_buffer(rx_queue, index);
-                       rx_buf->dma_addr = dma_addr + efx->rx_ip_align;
+                       rx_buf->dma_addr = dma_addr + efx->rx_ip_align +
+                                          XDP_PACKET_HEADROOM;
                        rx_buf->page = page;
-                       rx_buf->page_offset = page_offset + efx->rx_ip_align;
+                       rx_buf->page_offset = page_offset + efx->rx_ip_align +
+                                             XDP_PACKET_HEADROOM;
                        rx_buf->len = efx->rx_dma_len;
                        rx_buf->flags = 0;
                        ++rx_queue->added_count;