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Commit 98226208 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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mlx4: fix race accessing page->_count 



This is illegal to use atomic_set(&page->_count, ...) even if we 'own'
the page. Other entities in the kernel need to use get_page_unless_zero()
to get a reference to the page before testing page properties, so we could
loose a refcount increment.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ec916983

drivers/net/ethernet/mellanox/mlx4/en_rx.c

+3 −3
Original line number Diff line number Diff line
@@ -76,10 +76,10 @@ static int mlx4_alloc_pages(struct mlx4_en_priv *priv, 
	page_alloc->dma = dma;

	page_alloc->page_offset = frag_info->frag_align;

	/* Not doing get_page() for each frag is a big win

	 * on asymetric workloads.

	 * on asymetric workloads. Note we can not use atomic_set().

	 */

	atomic_set(&page->_count,

		   page_alloc->page_size / frag_info->frag_stride);

	atomic_add(page_alloc->page_size / frag_info->frag_stride - 1,

		   &page->_count);

	return 0;

}