This patch fixes an issue seen on Power systems with ixgbe which results
in skb list corruption and an eventual kernel oops. The following is what
was observed:
CPU 1 CPU2
============================ ============================
1: ixgbe_xmit_frame_ring ixgbe_clean_tx_irq
2: first->skb = skb eop_desc = tx_buffer->next_to_watch
3: ixgbe_tx_map read_barrier_depends()
4: wmb check adapter written status bit
5: first->next_to_watch = tx_desc napi_consume_skb(tx_buffer->skb ..);
6: writel(i, tx_ring->tail);
The read_barrier_depends is insufficient to ensure that tx_buffer->skb does not
get loaded prior to tx_buffer->next_to_watch, which then results in loading
a stale skb pointer. This patch replaces the read_barrier_depends with
smp_rmb to ensure loads are ordered with respect to the load of
tx_buffer->next_to_watch.
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
0a9a17e3bb