netdev - RE: [PATCH] Check for SKBTX_HW

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Date:   Tue, 12 Mar 2019 21:34:56 +0000
From:   "Keller, Jacob E" <jacob.e.keller@...el.com>
To:     Paul Thomas <pthomas8589@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH] Check for SKBTX_HW_TSTAMP in macb driver

> -----Original Message-----
> From: netdev-owner@...r.kernel.org [mailto:netdev-owner@...r.kernel.org] On
> Behalf Of Paul Thomas
> Sent: Tuesday, March 12, 2019 12:51 PM
> To: netdev@...r.kernel.org
> Cc: Paul Thomas <pthomas8589@...il.com>
> Subject: [PATCH] Check for SKBTX_HW_TSTAMP in macb driver
> 
> Make sure SKBTX_HW_TSTAMP (i.e. SOF_TIMESTAMPING_TX_HARDWARE) has been
> enabled for this skb
> This is a concept for discussion, more testing is needed.
> It does fix the issue where normal socks that aren't expecting a timestamp will not
> wake
> up on select.
> ---
>  drivers/net/ethernet/cadence/macb_main.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c
> b/drivers/net/ethernet/cadence/macb_main.c
> index ad099fd01b45..b2f184fc1370 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -898,11 +898,13 @@ static void macb_tx_interrupt(struct macb_queue *queue)
> 
>  			/* First, update TX stats if needed */
>  			if (skb) {
> -				if (gem_ptp_do_txstamp(queue, skb, desc) == 0) {
> -					/* skb now belongs to timestamp buffer
> -					 * and will be removed later
> -					 */
> -					tx_skb->skb = NULL;
> +				if(unlikely(skb_shinfo(skb)->tx_flags &
> SKBTX_HW_TSTAMP)) {

This should be && for logical AND. Technically a bitwise & will likely work, but it's not what you intended.

Thanks,
Jake

> +					if (gem_ptp_do_txstamp(queue, skb, desc)
> == 0) {
> +						/* skb now belongs to timestamp
> buffer
> +						 * and will be removed later
> +						 */
> +						tx_skb->skb = NULL;
> +					}
>  				}
>  				netdev_vdbg(bp->dev, "skb %u (data %p) TX
> complete\n",
>  					    macb_tx_ring_wrap(bp, tail),
> --
> 2.17.1