From ec91698360b3818ff426488a1529811f7a7ab87f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 10 Oct 2014 04:48:16 -0700 Subject: [PATCH] ixgbe: fix race accessing page->_count This is illegal to use atomic_set(&page->_count, 2) 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: Eric Dumazet Acked-by: Jeff Kirsher Signed-off-by: David S. Miller --- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c index d677b5a23b58..fec5212d4337 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c @@ -1865,12 +1865,10 @@ static bool ixgbe_add_rx_frag(struct ixgbe_ring *rx_ring, /* flip page offset to other buffer */ rx_buffer->page_offset ^= truesize; - /* - * since we are the only owner of the page and we need to - * increment it, just set the value to 2 in order to avoid - * an unecessary locked operation + /* Even if we own the page, we are not allowed to use atomic_set() + * This would break get_page_unless_zero() users. */ - atomic_set(&page->_count, 2); + atomic_inc(&page->_count); #else /* move offset up to the next cache line */ rx_buffer->page_offset += truesize;