[PATCH net-next V2 7/8] net: fec: don't transfer ownership until descriptor write is complete

On 2/5/2016 6:03 PM, Joshua Clayton wrote:

On Fri,  5 Feb 2016 14:52:49 -0700
Troy Kisky [off-list ref] wrote:

quoted

If you don't own it, you shouldn't write to it.

Signed-off-by: Troy Kisky <redacted>
---
 drivers/net/ethernet/freescale/fec_main.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c

b/drivers/net/ethernet/freescale/fec_main.c index ca2708d..97ca72a
100644 --- a/drivers/net/ethernet/freescale/fec_main.c

+++ b/drivers/net/ethernet/freescale/fec_main.c

@@ -390,6 +390,10 @@ fec_enet_txq_submit_frag_skb(struct

fec_enet_priv_tx_q *txq, 
 		bdp->cbd_bufaddr = cpu_to_fec32(addr);
 		bdp->cbd_datlen = cpu_to_fec16(frag_len);
+		/* Make sure the updates to rest of the descriptor
are
+		 * performed before transferring ownership.
+		 */
+		wmb();
 		bdp->cbd_sc = cpu_to_fec16(status);

You use almost exactly the same code in each place.
I'd prefer to have wmb(); bdp->cbd_sc = cpu_to_fec16(status) wrapped in
a function or function like macro, and put the comment in one place.

Thanks for the review. I added a patch to the end of the series to create a common
"trigger_tx" subroutine which should address this.