[PATCH net] ipv4: Fix updating SOF_TIMESTAMPING_OPT_ID when SKBTX_HW_TSTAMP is enabled

[PATCH net] ipv4: Fix updating SOF_TIMESTAMPING_OPT_ID when SKBTX_HW_TSTAMP is enabled

[Stephen Mallon]

Ensure that the unique timestamp identifier is incremented for skb hardware
timestamps, not just software timestamps.

Signed-off-by: Stephen Mallon <stephen.mallon@sydney.edu.au>
---
 net/ipv4/ip_output.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index c80188875f39..96ef1d467ba7 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -891,7 +891,7 @@ static int __ip_append_data(struct sock *sk,
 	mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
 	paged = !!cork->gso_size;
 
-	if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
+	if (cork->tx_flags & SKBTX_ANY_TSTAMP &&
 	    sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
 		tskey = sk->sk_tskey++;
 
-- 
2.18.1

Re: [PATCH net] ipv4: Fix updating SOF_TIMESTAMPING_OPT_ID when SKBTX_HW_TSTAMP is enabled

[Richard Cochran]

On Sun, Apr 28, 2019 at 03:45:21PM +1000, Stephen Mallon wrote:
> Ensure that the unique timestamp identifier is incremented for skb hardware
> timestamps, not just software timestamps.

Thanks for fixing this.  It has been at the back of my mind for a long
time, but since I don't use this feature... oh well.

This patch would be a candidate for stable kernels.  Can you please
add a Fixes: tag?

Thanks,
Richard

Re: [PATCH net] ipv4: Fix updating SOF_TIMESTAMPING_OPT_ID when SKBTX_HW_TSTAMP is enabled

[Willem de Bruijn]

On Sun, Apr 28, 2019 at 11:22 AM Richard Cochran
<richardcochran@gmail.com> wrote:
>
> On Sun, Apr 28, 2019 at 03:45:21PM +1000, Stephen Mallon wrote:
> > Ensure that the unique timestamp identifier is incremented for skb hardware
> > timestamps, not just software timestamps.
>
> Thanks for fixing this.  It has been at the back of my mind for a long
> time, but since I don't use this feature... oh well.
>
> This patch would be a candidate for stable kernels.  Can you please
> add a Fixes: tag?

It is debatable whether this is a fix or a new feature. It extends
SOF_TIMESTAMPING_OPT_ID to hardware timestamps. I don't think this
would be a stable candidate.

More importantly, note that __ip6_append_data has similar logic. For
consistency the two should be updated at the same time.

Re: [PATCH net] ipv4: Fix updating SOF_TIMESTAMPING_OPT_ID when SKBTX_HW_TSTAMP is enabled

[Richard Cochran]

On Sun, Apr 28, 2019 at 10:57:57PM -0400, Willem de Bruijn wrote:
> It is debatable whether this is a fix or a new feature. It extends
> SOF_TIMESTAMPING_OPT_ID to hardware timestamps. I don't think this
> would be a stable candidate.

Was the original series advertised as SW timestamping only?

If so, I missed that at the time.  After seeing it not work, I meant
to fix it, but never got around to it.  So to me this is a known
issue.
 
> More importantly, note that __ip6_append_data has similar logic. For
> consistency the two should be updated at the same time.

+1

Thanks,
Richard

Re: [PATCH net] ipv4: Fix updating SOF_TIMESTAMPING_OPT_ID when SKBTX_HW_TSTAMP is enabled

[Willem de Bruijn]

On Mon, Apr 29, 2019 at 11:02 AM Richard Cochran
<richardcochran@gmail.com> wrote:
>
> On Sun, Apr 28, 2019 at 10:57:57PM -0400, Willem de Bruijn wrote:
> > It is debatable whether this is a fix or a new feature. It extends
> > SOF_TIMESTAMPING_OPT_ID to hardware timestamps. I don't think this
> > would be a stable candidate.
>
> Was the original series advertised as SW timestamping only?

I did not intend to cover hardware timestamps at the time.

> If so, I missed that at the time.  After seeing it not work, I meant
> to fix it, but never got around to it.  So to me this is a known
> issue.

Understood. I certainly understand that view. I never use hw
timestamps, so it is a bit of a blind spot for me. If this is a safe
and predictable change, I don't care strongly about net vs net-next. I
don't think it meets the bar for stable, but that is not my call.

> > More importantly, note that __ip6_append_data has similar logic. For
> > consistency the two should be updated at the same time.
>
> +1
>
> Thanks,
> Richard

Re: [PATCH net] ipv4: Fix updating SOF_TIMESTAMPING_OPT_ID when SKBTX_HW_TSTAMP is enabled

[Stephen Mallon]

On Mon, Apr 29, 2019 at 11:32:08AM -0400, Willem de Bruijn wrote:
> On Mon, Apr 29, 2019 at 11:02 AM Richard Cochran
> <richardcochran@gmail.com> wrote:
> >
> > On Sun, Apr 28, 2019 at 10:57:57PM -0400, Willem de Bruijn wrote:
> > > It is debatable whether this is a fix or a new feature. It extends
> > > SOF_TIMESTAMPING_OPT_ID to hardware timestamps. I don't think this
> > > would be a stable candidate.
> >
> > Was the original series advertised as SW timestamping only?
> 
> I did not intend to cover hardware timestamps at the time.
> 
> > If so, I missed that at the time.  After seeing it not work, I meant
> > to fix it, but never got around to it.  So to me this is a known
> > issue.
> 
> Understood. I certainly understand that view. I never use hw
> timestamps, so it is a bit of a blind spot for me. If this is a safe
> and predictable change, I don't care strongly about net vs net-next. I
> don't think it meets the bar for stable, but that is not my call.

I've found that SOF_TIMESTAMPING_OPT_ID already works with hardware timestamps
for TCP just not datagram sockets and so I though this was a fix.

> > > More importantly, note that __ip6_append_data has similar logic. For
> > > consistency the two should be updated at the same time.
> >
> > +1
> >
> > Thanks,
> > Richard

Thanks for the feedback, I'll update with __ip6_append_data.

Re: [PATCH net] ipv4: Fix updating SOF_TIMESTAMPING_OPT_ID when SKBTX_HW_TSTAMP is enabled

[Richard Cochran]

On Tue, Apr 30, 2019 at 11:17:32AM +1000, Stephen Mallon wrote:
> 
> I've found that SOF_TIMESTAMPING_OPT_ID already works with hardware timestamps
> for TCP just not datagram sockets and so I though this was a fix.

Right, so if HW time stamping worked for TCP but not for UDP, then I
would call it a regression to be fixed in stable.

Thanks,
Richard