On Wed, Jan 04, 2023 at 06:45:33PM +0100, Stefano Brivio wrote:
> On Fri,  9 Dec 2022 16:42:28 +1100
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > In passt mode, when writing frames to the qemu socket, we might get a short
> > send.  If we ignored this and carried on, the qemu socket would get out of
> > sync, because the bytes we actually sent wouldn't correspond  to the length
> > header we already sent.  tap_send_frames_passt() handles that by doing a
> > a blocking send to complete the message, but it has a few flaws:
> >  * We only attempt to resend once: although it's unlikely in practice,
> >    nothing prevents the blocking send() from also being short
> >  * We print a debug error if send() returns non-zero.. but send() returns
> >    the number of bytes sent, so we actually want it to return the length
> >    of the remaining data.
> > 
> > Correct those flaws and also be a bit more thorough about reporting
> > problems here.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  tap.c | 51 ++++++++++++++++++++++++++++++++++++++-------------
> >  1 file changed, 38 insertions(+), 13 deletions(-)
> > 
> > diff --git a/tap.c b/tap.c
> > index 5ec6b70..4fb27ca 100644
> > --- a/tap.c
> > +++ b/tap.c
> > @@ -326,13 +326,39 @@ static void tap_send_frames_pasta(struct ctx *c,
> >  	}
> >  }
> >  
> > +/**
> > + * tap_send_remainder() - Send remainder of a partiall sent frame
> 
> s/partiall/partially/

Fixed.

> > + * @c:		Execution context
> > + * @iov:	Partially sent buffer
> > + * @offset:	Number of bytes already sent from @iov
> > + *
> > + * #syscalls:passt sendto
> 
> We should probably drop this, it's actually send(2) on armv6/armv7 and
> ppc64le, sendto(2) otherwise -- initially I sprinkled those annotations
> all over the place to show where specific calls were issued (and make
> it easier to drop them from the filter if calls disappeared) but I
> think it's not really practical for send(3).

Heh, right.  Done.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson