[Intel-wired-lan] [PATCH net v1] igc: Don't clear the large buffer bit before memory release

[Intel-wired-lan] [PATCH net v1] igc: Don't clear the large buffer bit before memory release

[Vedang Patel]

When XDP is enabled, it uses large buffers to accomodate headroom and
tailroom required by XDP infrastructure. But, it clears the large buffer
bit before unmapping the buffer.

dma_unmap_page_attrs() (called by igc_clean_rx_ring_page_shared()) needs
size of the buffer to unmap. If the large buffer bit is cleared before
calling igc_clean_rx_ring_page_shared(), all of the memory won't be
unmapped.

Fixes: 2e739318416b ("igc: Add initial XDP support")

Signed-off-by: Vedang Patel <vedang.patel@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 0bcdf05d03f0..b96b745fdb65 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -418,13 +418,13 @@ static void igc_clean_rx_ring_xsk_pool(struct igc_ring *ring)
  */
 static void igc_clean_rx_ring(struct igc_ring *ring)
 {
-	clear_ring_uses_large_buffer(ring);
-
 	if (ring->xsk_pool)
 		igc_clean_rx_ring_xsk_pool(ring);
 	else
 		igc_clean_rx_ring_page_shared(ring);
 
+	clear_ring_uses_large_buffer(ring);
+
 	ring->next_to_alloc = 0;
 	ring->next_to_clean = 0;
 	ring->next_to_use = 0;
-- 
2.17.1

[Intel-wired-lan] [PATCH net v1] igc: Don't clear the large buffer bit before memory release

[Maciej Fijalkowski]

On Thu, Jan 07, 2021 at 10:56:54AM -0800, Vedang Patel wrote:
> When XDP is enabled, it uses large buffers to accomodate headroom and
> tailroom required by XDP infrastructure. But, it clears the large buffer
> bit before unmapping the buffer.
> 
> dma_unmap_page_attrs() (called by igc_clean_rx_ring_page_shared()) needs
> size of the buffer to unmap. If the large buffer bit is cleared before
> calling igc_clean_rx_ring_page_shared(), all of the memory won't be
> unmapped.
> 
> Fixes: 2e739318416b ("igc: Add initial XDP support")
> 
> Signed-off-by: Vedang Patel <vedang.patel@intel.com>
> ---
>  drivers/net/ethernet/intel/igc/igc_main.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index 0bcdf05d03f0..b96b745fdb65 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -418,13 +418,13 @@ static void igc_clean_rx_ring_xsk_pool(struct igc_ring *ring)
>   */
>  static void igc_clean_rx_ring(struct igc_ring *ring)
>  {
> -	clear_ring_uses_large_buffer(ring);
> -
>  	if (ring->xsk_pool)
>  		igc_clean_rx_ring_xsk_pool(ring);
>  	else
>  		igc_clean_rx_ring_page_shared(ring);

This code is not yet upstreamed AFAICT. Probably you should ask Andre to
include this fix onto igc's AFXDP support?

>  
> +	clear_ring_uses_large_buffer(ring);
> +
>  	ring->next_to_alloc = 0;
>  	ring->next_to_clean = 0;
>  	ring->next_to_use = 0;
> -- 
> 2.17.1
> 
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