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net/mlx4_en: do batched put_page using atomic_sub

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This patch fixes couple error paths after allocation failures.
Atomic set of page reference counter is safe only if it is zero,
otherwise set can race with any speculative get_page_unless_zero.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Konstantin Khlebnikov 2016-04-18 14:34:05 +03:00 committed by David S. Miller
parent 04aeb56a17
commit 851b10d608
1 changed files with 6 additions and 2 deletions
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8
drivers/net/ethernet/mellanox/mlx4/en_rx.c
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@ -126,7 +126,9 @@ static int mlx4_en_alloc_frags(struct mlx4_en_priv *priv,
dma_unmap_page(priv->ddev, page_alloc[i].dma,
page_alloc[i].page_size, PCI_DMA_FROMDEVICE);
page = page_alloc[i].page;
set_page_count(page, 1);
/* Revert changes done by mlx4_alloc_pages */
page_ref_sub(page, page_alloc[i].page_size /
priv->frag_info[i].frag_stride - 1);
put_page(page);
}
}
@ -176,7 +178,9 @@ static int mlx4_en_init_allocator(struct mlx4_en_priv *priv,
dma_unmap_page(priv->ddev, page_alloc->dma,
page_alloc->page_size, PCI_DMA_FROMDEVICE);
page = page_alloc->page;
set_page_count(page, 1);
/* Revert changes done by mlx4_alloc_pages */
page_ref_sub(page, page_alloc->page_size /
priv->frag_info[i].frag_stride - 1);
put_page(page);
page_alloc->page = NULL;
}