On Thu, Oct 19, 2017 at 12:07 PM, Jean-Philippe Brucker
<jean-philippe.bruc...@arm.com> wrote:
> When the driver cannot map a TX buffer, instead of rolling back
> gracefully and retrying later, we currently get a panic:
>
> [ 159.885994] igb 0000:00:00.0: TX DMA map failed
> [ 159.886588] Unable to handle kernel paging request at virtual address
> ffff00000a08c7a8
> ...
> [ 159.897031] PC is at igb_xmit_frame_ring+0x9c8/0xcb8
>
> Fix the erroneous test that leads to this situation.
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe.bruc...@arm.com>
> ---
> drivers/net/ethernet/intel/igb/igb_main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c
> b/drivers/net/ethernet/intel/igb/igb_main.c
> index fd4a46b03cc8..ea69af267d63 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -5326,7 +5326,7 @@ static int igb_tx_map(struct igb_ring *tx_ring,
> DMA_TO_DEVICE);
> dma_unmap_len_set(tx_buffer, len, 0);
>
> - if (i--)
> + if (i-- == 0)
> i += tx_ring->count;
> tx_buffer = &tx_ring->tx_buffer_info[i];
> }
The fix looks fine to me, though I will probably want to go back and
update the code to simplify this since I realize part of the issue is
that there is a bunch of unneeded complexity I introduced here. It
looks like we have the same problem in ixgbe that needs to be
addressed as well.
Fixes: 7cc6fd4c60f2 ("igb: Don't bother clearing Tx buffer_info in
igb_clean_tx_ring")
Acked-by: Alexander Duyck <alexander.h.du...@intel.com>
