Re: [PATCH net 2/3] net: tls: Cancel RX async resync request on rdc_delta overflow

[Sabrina Dubroca <sd@queasysnail.net>]

2025-09-28, 09:35:48 +0300, Shahar Shitrit wrote:
> 
> 
> On 22/09/2025 18:54, Sabrina Dubroca wrote:
> > 2025-09-22, 10:18:52 +0300, Shahar Shitrit wrote:
> >>
> >>
> >> On 14/09/2025 21:53, Jakub Kicinski wrote:
> >>> On Wed, 10 Sep 2025 09:47:40 +0300 Tariq Toukan wrote:
> >>>> When a netdev issues an RX async resync request, the TLS module
> >>>> increments rcd_delta for each new record that arrives. This tracks
> >>>> how far the current record is from the point where synchronization
> >>>> was lost.
> >>>>
> >>>> When rcd_delta reaches its threshold, it indicates that the device
> >>>> response is either excessively delayed or unlikely to arrive at all
> >>>> (at that point, tcp_sn may have wrapped around, so a match would no
> >>>> longer be valid anyway).
> >>>>
> >>>> Previous patch introduced tls_offload_rx_resync_async_request_cancel()
> >>>> to explicitly cancel resync requests when a device response failure
> >>>> is detected.
> >>>>
> >>>> This patch adds a final safeguard: cancel the async resync request when
> >>>> rcd_delta crosses its threshold, as reaching this point implies that
> >>>> earlier cancellation did not occur.
> >>>
> >>> Missing a Fixes tag
> >> Will add
> >>>
> >>>> diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
> >>>> index f672a62a9a52..56c14f1647a4 100644
> >>>> --- a/net/tls/tls_device.c
> >>>> +++ b/net/tls/tls_device.c
> >>>> @@ -721,8 +721,11 @@ tls_device_rx_resync_async(struct tls_offload_resync_async *resync_async,
> >>>>  		/* shouldn't get to wraparound:
> >>>>  		 * too long in async stage, something bad happened
> >>>>  		 */
> >>>> -		if (WARN_ON_ONCE(resync_async->rcd_delta == USHRT_MAX))
> >>>> +		if (WARN_ON_ONCE(resync_async->rcd_delta == USHRT_MAX)) {
> >>>> +			/* cancel resync request */
> >>>> +			atomic64_set(&resync_async->req, 0);
> >>>
> >>> we should probably use the helper added by the previous patch (I'd
> >>> probably squash them TBH)
> >>
> >> It's not trivial to use the helper here, since we don't have the socket.
> > 
> > tls_device_rx_resync_async doesn't currently get the socket, but it
> > has only one caller, tls_device_rx_resync_new_rec, which does. So
> > tls_device_rx_resync_async could easily get the socket. Or just pass
> > resync_async to tls_offload_rx_resync_async_request_cancel, since
> > that's what it really needs?
> > 
> yes these are options, but we don't like too much passing the socket to
> tls_device_rx_resync_new_rec() merely for this matter.

Why not? If you felt the need to add a comment saying we're canceling
the request, using a helper instead that says it does the canceling is
a pretty decent reason to add whatever argument
tls_device_rx_resync_async needs (or swap resync_async for the socket
if you don't want to add another argument).

> Also we wanted to
> keep tls_offload_rx_resync_async_request_cancel in the same format of
> tls_offload_rx_resync_async_request_start/end meaning to have the socket
> as a parameter.

Then they could easily be changed to make the 3 helpers consistent
(all taking resync_async), since
tls_offload_rx_resync_async_request_start/end are used exactly once
each.

-- 
Sabrina