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authorEric Dumazet <edumazet@google.com>2014-10-10 04:48:16 -0700
committerDavid S. Miller <davem@davemloft.net>2014-10-10 15:37:28 -0400
commitec91698360b3818ff426488a1529811f7a7ab87f (patch)
tree25eaf1eae76db5e562eae34d0ea921d03566c8c0 /drivers/net
parent00cd5adb0313f540aa58672d14e764d164586a43 (diff)
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 <edumazet@google.com> Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/ethernet/intel/ixgbe/ixgbe_main.c8
1 files 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;