Subject: [net-next 09/15] net/mlx5e: RX, Fix releasing page_pool pages twice for striding RQ

From: Saeed Mahameed <[email-masked]>
Date: Thu, 20 Apr 2023 18:38:44 -0700

From: Dragos Tatulea <[email-masked]>

mlx5e_free_rx_descs is responsible for calling the dealloc_wqe op which
returns pages to the page_pool. This can happen during flush or close.
For XSK, the regular RQ is flushed (when replaced by the XSK RQ) and
also closed later. This is normally not a problem as the wqe list is
empty on a second call to mlx5e_free_rx_descs. However, for striding RQ,
the previously released wqes from the list will appear as missing
and will be released a second time by mlx5e_free_rx_missing_descs.

This patch sets the no release bits on the striding RQ wqes in the
dealloc_wqe op to prevent releasing the pages a second time.

Please note that the bits are set only in the control path during
close and not in the data path.

Fixes: 4c2a13236807 ("net/mlx5e: RX, Defer page release in striding rq for better recycling")
Signed-off-by: Dragos Tatulea <[email-masked]>
Reviewed-by: Tariq Toukan <[email-masked]>
Signed-off-by: Saeed Mahameed <[email-masked]>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index a8c2ae389d6c..5dc907541094 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -861,6 +861,11 @@ static void mlx5e_dealloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix)
 	struct mlx5e_mpw_info *wi = mlx5e_get_mpw_info(rq, ix);
 	/* This function is called on rq/netdev close. */
 	mlx5e_free_rx_mpwqe(rq, wi);
+
+	/* Avoid a second release of the wqe pages: dealloc is called also
+	 * for missing wqes on an already flushed RQ.
+	 */
+	bitmap_fill(wi->skip_release_bitmap, rq->mpwqe.pages_per_wqe);
 }
 
 INDIRECT_CALLABLE_SCOPE bool mlx5e_post_rx_wqes(struct mlx5e_rq *rq)
-- 
2.39.2