netdev - [net-next 09/15] net/mlx5e: RX, Fix releasing page

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Message-Id: <20230421013850.349646-10-saeed@kernel.org>
Date:   Thu, 20 Apr 2023 18:38:44 -0700
From:   Saeed Mahameed <saeed@...nel.org>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     Saeed Mahameed <saeedm@...dia.com>, netdev@...r.kernel.org,
        Tariq Toukan <tariqt@...dia.com>,
        Dragos Tatulea <dtatulea@...dia.com>
Subject: [net-next 09/15] net/mlx5e: RX, Fix releasing page_pool pages twice for striding RQ

From: Dragos Tatulea <dtatulea@...dia.com>

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 <dtatulea@...dia.com>
Reviewed-by: Tariq Toukan <tariqt@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
---
 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