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net/mlx4_en: do batched put_page using atomic_sub 

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 @@ out:
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 @@ out:
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;
}