[PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Michael S. Tsirkin]

virtio_net_hdr_to_skb() refuses packets whose checksum metadata
it cannot make sense of, but the vector raw transport ignored
its return value: rejected packets went on into the stack with
their metadata unvalidated.

Propagate the failure.

Assisted-by: LLM
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 arch/um/drivers/vector_transports.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c
index e1fb2a76fdff..8b7548458663 100644
--- a/arch/um/drivers/vector_transports.c
+++ b/arch/um/drivers/vector_transports.c
@@ -210,7 +210,9 @@ static int raw_verify_header(
 		return 1;
 
 	skb_set_network_header(skb, ETH_HLEN);
-	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
+	if (virtio_net_hdr_to_skb(skb, vheader,
+			virtio_legacy_is_little_endian()) < 0)
+		return -1;
 	return 0;
 }
 
-- 
MST

[PATCH net-next v2 3/7] um: vector: trim skbs before verifying the header

[Michael S. Tsirkin]

The vector receive path over-allocates the skb and only trims it
to the received length after the transport header is verified.

A follow up patch will complete the packet checksum in software within
virtio_net_hdr_to_skb so we need the packet trimmed (otherwise the
checksum would be computed incorrectly over the unreceived tail of the
buffer).

Trim first, so the import sees the packet as it was received.

Assisted-by: LLM
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 arch/um/drivers/vector_kern.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index 8a70b3a62553..1afbef78df72 100644
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c
@@ -865,6 +865,7 @@ static int vector_legacy_rx(struct vector_private *vp)
 
 	if (skb != NULL) {
 		if (pkt_len > vp->header_size) {
+			pskb_trim(skb, pkt_len - vp->rx_header_size);
 			if (vp->header_size > 0) {
 				header_check = vp->verify_header(
 					vp->header_rxbuffer, skb, vp);
@@ -879,7 +880,6 @@ static int vector_legacy_rx(struct vector_private *vp)
 					skb->ip_summed = CHECKSUM_UNNECESSARY;
 				}
 			}
-			pskb_trim(skb, pkt_len - vp->rx_header_size);
 			skb->protocol = eth_type_trans(skb, skb->dev);
 			vp->dev->stats.rx_bytes += skb->len;
 			vp->dev->stats.rx_packets++;
@@ -981,6 +981,8 @@ static int vector_mmsg_rx(struct vector_private *vp, int budget)
 	for (i = 0; i < packet_count; i++) {
 		skb = (*skbuff_vector);
 		if (mmsg_vector->msg_len > vp->header_size) {
+			pskb_trim(skb,
+				mmsg_vector->msg_len - vp->rx_header_size);
 			if (vp->header_size > 0) {
 				header_check = vp->verify_header(
 					mmsg_vector->msg_hdr.msg_iov->iov_base,
@@ -1005,8 +1007,6 @@ static int vector_mmsg_rx(struct vector_private *vp, int budget)
 					skb->ip_summed = CHECKSUM_UNNECESSARY;
 				}
 			}
-			pskb_trim(skb,
-				mmsg_vector->msg_len - vp->rx_header_size);
 			skb->protocol = eth_type_trans(skb, skb->dev);
 			/*
 			 * We do not need to lock on updating stats here
-- 
MST

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Johannes Berg]

On Thu, 2026-10-15 at 08:41 -0400, Michael S. Tsirkin wrote:
> virtio_net_hdr_to_skb() refuses packets whose checksum metadata
> it cannot make sense of, but the vector raw transport ignored
> its return value: rejected packets went on into the stack with
> their metadata unvalidated.
> 
> Propagate the failure.
> 
> Assisted-by: LLM
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  arch/um/drivers/vector_transports.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c
> index e1fb2a76fdff..8b7548458663 100644
> --- a/arch/um/drivers/vector_transports.c
> +++ b/arch/um/drivers/vector_transports.c
> @@ -210,7 +210,9 @@ static int raw_verify_header(
>  		return 1;
>  
>  	skb_set_network_header(skb, ETH_HLEN);
> -	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
> +	if (virtio_net_hdr_to_skb(skb, vheader,
> +			virtio_legacy_is_little_endian()) < 0)
> +		return -1;
>  	return 0;
> 

Seems it'd be simpler to just

	return virtio_net_hdr_to_skb(...);

As far as I can tell, the function only returns -EINVAL or 0 (never a
positive value), and the caller only cares about negative (error) or
positive (no checksum needed), so that'd be equivalent?

johannes

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Michael S. Tsirkin]

On Thu, Oct 15, 2026 at 02:47:01PM +0200, Johannes Berg wrote:
> On Thu, 2026-10-15 at 08:41 -0400, Michael S. Tsirkin wrote:
> > virtio_net_hdr_to_skb() refuses packets whose checksum metadata
> > it cannot make sense of, but the vector raw transport ignored
> > its return value: rejected packets went on into the stack with
> > their metadata unvalidated.
> > 
> > Propagate the failure.
> > 
> > Assisted-by: LLM
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  arch/um/drivers/vector_transports.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c
> > index e1fb2a76fdff..8b7548458663 100644
> > --- a/arch/um/drivers/vector_transports.c
> > +++ b/arch/um/drivers/vector_transports.c
> > @@ -210,7 +210,9 @@ static int raw_verify_header(
> >  		return 1;
> >  
> >  	skb_set_network_header(skb, ETH_HLEN);
> > -	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
> > +	if (virtio_net_hdr_to_skb(skb, vheader,
> > +			virtio_legacy_is_little_endian()) < 0)
> > +		return -1;
> >  	return 0;
> > 
> 
> Seems it'd be simpler to just
> 
> 	return virtio_net_hdr_to_skb(...);
> 
> As far as I can tell, the function only returns -EINVAL or 0 (never a
> positive value), and the caller only cares about negative (error) or
> positive (no checksum needed), so that'd be equivalent?
> 
> johannes

if raw_verify_header can safely return any errno - i did not want to
audit it.

-- 
MST

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Johannes Berg]

On Thu, 2026-10-15 at 08:52 -0400, Michael S. Tsirkin wrote:
> On Thu, Oct 15, 2026 at 02:47:01PM +0200, Johannes Berg wrote:
> > On Thu, 2026-10-15 at 08:41 -0400, Michael S. Tsirkin wrote:
> > > virtio_net_hdr_to_skb() refuses packets whose checksum metadata
> > > it cannot make sense of, but the vector raw transport ignored
> > > its return value: rejected packets went on into the stack with
> > > their metadata unvalidated.
> > > 
> > > Propagate the failure.
> > > 
> > > Assisted-by: LLM
> > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > ---
> > >  arch/um/drivers/vector_transports.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c
> > > index e1fb2a76fdff..8b7548458663 100644
> > > --- a/arch/um/drivers/vector_transports.c
> > > +++ b/arch/um/drivers/vector_transports.c
> > > @@ -210,7 +210,9 @@ static int raw_verify_header(
> > >  		return 1;
> > >  
> > >  	skb_set_network_header(skb, ETH_HLEN);
> > > -	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
> > > +	if (virtio_net_hdr_to_skb(skb, vheader,
> > > +			virtio_legacy_is_little_endian()) < 0)
> > > +		return -1;
> > >  	return 0;
> > > 
> > 
> > Seems it'd be simpler to just
> > 
> > 	return virtio_net_hdr_to_skb(...);
> > 
> > As far as I can tell, the function only returns -EINVAL or 0 (never a
> > positive value), and the caller only cares about negative (error) or
> > positive (no checksum needed), so that'd be equivalent?
> > 
> > johannes
> 
> if raw_verify_header can safely return any errno - i did not want to
> audit it.

You already used an LLM and still didn't want to? ;-)

I checked briefly (by hand) and it seems fine, it's assigned to the
function pointer, which only has two callers on the _kern.c side.

johannes

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Willem de Bruijn]

Michael S. Tsirkin wrote:
> virtio_net_hdr_to_skb() refuses packets whose checksum metadata
> it cannot make sense of, but the vector raw transport ignored
> its return value: rejected packets went on into the stack with
> their metadata unvalidated.
> 
> Propagate the failure.
> 
> Assisted-by: LLM
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  arch/um/drivers/vector_transports.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c
> index e1fb2a76fdff..8b7548458663 100644
> --- a/arch/um/drivers/vector_transports.c
> +++ b/arch/um/drivers/vector_transports.c
> @@ -210,7 +210,9 @@ static int raw_verify_header(
>  		return 1;
>  
>  	skb_set_network_header(skb, ETH_HLEN);
> -	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
> +	if (virtio_net_hdr_to_skb(skb, vheader,
> +			virtio_legacy_is_little_endian()) < 0)
> +		return -1;

Should this return 1, like the above?

Not sure whether the verify_header return value is well defined beyond
just boolean.

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Michael S. Tsirkin]

On Thu, Oct 15, 2026 at 02:55:23PM +0200, Johannes Berg wrote:
> On Thu, 2026-10-15 at 08:52 -0400, Michael S. Tsirkin wrote:
> > On Thu, Oct 15, 2026 at 02:47:01PM +0200, Johannes Berg wrote:
> > > On Thu, 2026-10-15 at 08:41 -0400, Michael S. Tsirkin wrote:
> > > > virtio_net_hdr_to_skb() refuses packets whose checksum metadata
> > > > it cannot make sense of, but the vector raw transport ignored
> > > > its return value: rejected packets went on into the stack with
> > > > their metadata unvalidated.
> > > > 
> > > > Propagate the failure.
> > > > 
> > > > Assisted-by: LLM
> > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > ---
> > > >  arch/um/drivers/vector_transports.c | 4 +++-
> > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c
> > > > index e1fb2a76fdff..8b7548458663 100644
> > > > --- a/arch/um/drivers/vector_transports.c
> > > > +++ b/arch/um/drivers/vector_transports.c
> > > > @@ -210,7 +210,9 @@ static int raw_verify_header(
> > > >  		return 1;
> > > >  
> > > >  	skb_set_network_header(skb, ETH_HLEN);
> > > > -	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
> > > > +	if (virtio_net_hdr_to_skb(skb, vheader,
> > > > +			virtio_legacy_is_little_endian()) < 0)
> > > > +		return -1;
> > > >  	return 0;
> > > > 
> > > 
> > > Seems it'd be simpler to just
> > > 
> > > 	return virtio_net_hdr_to_skb(...);
> > > 
> > > As far as I can tell, the function only returns -EINVAL or 0 (never a
> > > positive value), and the caller only cares about negative (error) or
> > > positive (no checksum needed), so that'd be equivalent?
> > > 
> > > johannes
> > 
> > if raw_verify_header can safely return any errno - i did not want to
> > audit it.
> 
> You already used an LLM and still didn't want to? ;-)

I don't really trust it to do code audits especially in code I
do not test.

> I checked briefly (by hand) and it seems fine, it's assigned to the
> function pointer, which only has two callers on the _kern.c side.
> 
> johannes

Thanks, will make the change.

-- 
MST

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Michael S. Tsirkin]

On Thu, Oct 15, 2026 at 01:19:22PM -0400, Willem de Bruijn wrote:
> Michael S. Tsirkin wrote:
> > virtio_net_hdr_to_skb() refuses packets whose checksum metadata
> > it cannot make sense of, but the vector raw transport ignored
> > its return value: rejected packets went on into the stack with
> > their metadata unvalidated.
> > 
> > Propagate the failure.
> > 
> > Assisted-by: LLM
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  arch/um/drivers/vector_transports.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c
> > index e1fb2a76fdff..8b7548458663 100644
> > --- a/arch/um/drivers/vector_transports.c
> > +++ b/arch/um/drivers/vector_transports.c
> > @@ -210,7 +210,9 @@ static int raw_verify_header(
> >  		return 1;
> >  
> >  	skb_set_network_header(skb, ETH_HLEN);
> > -	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
> > +	if (virtio_net_hdr_to_skb(skb, vheader,
> > +			virtio_legacy_is_little_endian()) < 0)
> > +		return -1;
> 
> Should this return 1, like the above?
> 
> Not sure whether the verify_header return value is well defined beyond
> just boolean.

                                header_check = vp->verify_header(
                                        vp->header_rxbuffer, skb, vp);

                              if (header_check < 0) {
                                        dev_kfree_skb_irq(skb);
                                        vp->dev->stats.rx_dropped++;
                                        vp->estats.rx_encaps_errors++;
                                        return 0;
                                }
                                if (header_check > 0) {
                                        vp->estats.rx_csum_offload_good++;
                                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                                }


apparently? maybe i misunderstand.

-- 
MST

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Michael S. Tsirkin]

On Thu, Oct 15, 2026 at 02:55:23PM +0200, Johannes Berg wrote:
> On Thu, 2026-10-15 at 08:52 -0400, Michael S. Tsirkin wrote:
> > On Thu, Oct 15, 2026 at 02:47:01PM +0200, Johannes Berg wrote:
> > > On Thu, 2026-10-15 at 08:41 -0400, Michael S. Tsirkin wrote:
> > > > virtio_net_hdr_to_skb() refuses packets whose checksum metadata
> > > > it cannot make sense of, but the vector raw transport ignored
> > > > its return value: rejected packets went on into the stack with
> > > > their metadata unvalidated.
> > > > 
> > > > Propagate the failure.
> > > > 
> > > > Assisted-by: LLM
> > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > ---
> > > >  arch/um/drivers/vector_transports.c | 4 +++-
> > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c
> > > > index e1fb2a76fdff..8b7548458663 100644
> > > > --- a/arch/um/drivers/vector_transports.c
> > > > +++ b/arch/um/drivers/vector_transports.c
> > > > @@ -210,7 +210,9 @@ static int raw_verify_header(
> > > >  		return 1;
> > > >  
> > > >  	skb_set_network_header(skb, ETH_HLEN);
> > > > -	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
> > > > +	if (virtio_net_hdr_to_skb(skb, vheader,
> > > > +			virtio_legacy_is_little_endian()) < 0)
> > > > +		return -1;
> > > >  	return 0;
> > > > 
> > > 
> > > Seems it'd be simpler to just
> > > 
> > > 	return virtio_net_hdr_to_skb(...);
> > > 
> > > As far as I can tell, the function only returns -EINVAL or 0 (never a
> > > positive value), and the caller only cares about negative (error) or
> > > positive (no checksum needed), so that'd be equivalent?
> > > 
> > > johannes
> > 
> > if raw_verify_header can safely return any errno - i did not want to
> > audit it.
> 
> You already used an LLM and still didn't want to? ;-)
> 
> I checked briefly (by hand) and it seems fine, it's assigned to the
> function pointer, which only has two callers on the _kern.c side.
> 
> johannes


                               header_check = vp->verify_header(
                                        mmsg_vector->msg_hdr.msg_iov->iov_base,
                                        skb,
                                        vp
                                );
                                if (header_check < 0) {
                                /* Overlay header failed to verify - discard.
                                 * We can actually keep this skb and reuse it,
                                 * but that will make the prep logic too
                                 * complex.
                                 */
                                        dev_kfree_skb_irq(skb);
                                        vp->estats.rx_encaps_errors++;
                                        (*skbuff_vector) = NULL;
                                        mmsg_vector++;
                                        skbuff_vector++;
                                        continue;
                                }
                                if (header_check > 0) {
                                        vp->estats.rx_csum_offload_good++;
                                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                                }



so any negative is fine, but if we return 1 then it will force to CHECKSUM_UNNECESSARY
which I am not sure is what was intended?


-- 
MST

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Johannes Berg]

On Fri, 2026-10-16 at 05:43 -0400, Michael S. Tsirkin wrote:
> 
> > > > > -	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
> > > > > +	if (virtio_net_hdr_to_skb(skb, vheader,
> > > > > +			virtio_legacy_is_little_endian()) < 0)
> > > > > +		return -1;
> > > > >  	return 0;
> > > > > 
> > > > 
> > > > Seems it'd be simpler to just
> > > > 
> > > > 	return virtio_net_hdr_to_skb(...);
> > > > 
> > > > As far as I can tell, the function only returns -EINVAL or 0 (never a
> > > > positive value), and the caller only cares about negative (error) or
> > > > positive (no checksum needed), so that'd be equivalent?
> > > > 
> > > > johannes
> > > 
> > > if raw_verify_header can safely return any errno - i did not want to
> > > audit it.
> > 
> > You already used an LLM and still didn't want to? ;-)
> > 
> > I checked briefly (by hand) and it seems fine, it's assigned to the
> > function pointer, which only has two callers on the _kern.c side.
> > 
> > johannes
> 
> 
>                                header_check = vp->verify_header(
>                                         mmsg_vector->msg_hdr.msg_iov->iov_base,
>                                         skb,
>                                         vp
>                                 );
>                                 if (header_check < 0) {
>                                 /* Overlay header failed to verify - discard.
>                                  * We can actually keep this skb and reuse it,
>                                  * but that will make the prep logic too
>                                  * complex.
>                                  */
>                                         dev_kfree_skb_irq(skb);
>                                         vp->estats.rx_encaps_errors++;
>                                         (*skbuff_vector) = NULL;
>                                         mmsg_vector++;
>                                         skbuff_vector++;
>                                         continue;
>                                 }
>                                 if (header_check > 0) {
>                                         vp->estats.rx_csum_offload_good++;
>                                         skb->ip_summed = CHECKSUM_UNNECESSARY;
>                                 }
> 
> 
> 
> so any negative is fine, but if we return 1 then it will force to CHECKSUM_UNNECESSARY
> which I am not sure is what was intended?
> 
Right, but virtio_net_hdr_to_skb() cannot return 1, only 0 on success
and -ERROR on failure?

johannes

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Michael S. Tsirkin]

On Fri, Oct 16, 2026 at 11:44:16AM +0200, Johannes Berg wrote:
> On Fri, 2026-10-16 at 05:43 -0400, Michael S. Tsirkin wrote:
> > 
> > > > > > -	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
> > > > > > +	if (virtio_net_hdr_to_skb(skb, vheader,
> > > > > > +			virtio_legacy_is_little_endian()) < 0)
> > > > > > +		return -1;
> > > > > >  	return 0;
> > > > > > 
> > > > > 
> > > > > Seems it'd be simpler to just
> > > > > 
> > > > > 	return virtio_net_hdr_to_skb(...);
> > > > > 
> > > > > As far as I can tell, the function only returns -EINVAL or 0 (never a
> > > > > positive value), and the caller only cares about negative (error) or
> > > > > positive (no checksum needed), so that'd be equivalent?
> > > > > 
> > > > > johannes
> > > > 
> > > > if raw_verify_header can safely return any errno - i did not want to
> > > > audit it.
> > > 
> > > You already used an LLM and still didn't want to? ;-)
> > > 
> > > I checked briefly (by hand) and it seems fine, it's assigned to the
> > > function pointer, which only has two callers on the _kern.c side.
> > > 
> > > johannes
> > 
> > 
> >                                header_check = vp->verify_header(
> >                                         mmsg_vector->msg_hdr.msg_iov->iov_base,
> >                                         skb,
> >                                         vp
> >                                 );
> >                                 if (header_check < 0) {
> >                                 /* Overlay header failed to verify - discard.
> >                                  * We can actually keep this skb and reuse it,
> >                                  * but that will make the prep logic too
> >                                  * complex.
> >                                  */
> >                                         dev_kfree_skb_irq(skb);
> >                                         vp->estats.rx_encaps_errors++;
> >                                         (*skbuff_vector) = NULL;
> >                                         mmsg_vector++;
> >                                         skbuff_vector++;
> >                                         continue;
> >                                 }
> >                                 if (header_check > 0) {
> >                                         vp->estats.rx_csum_offload_good++;
> >                                         skb->ip_summed = CHECKSUM_UNNECESSARY;
> >                                 }
> > 
> > 
> > 
> > so any negative is fine, but if we return 1 then it will force to CHECKSUM_UNNECESSARY
> > which I am not sure is what was intended?
> > 
> Right, but virtio_net_hdr_to_skb() cannot return 1, only 0 on success
> and -ERROR on failure?
> 
> johannes

After this patchset, it can, to signal slow path software checksum.
I'm changing callers first so that changing the function itself
does not break bisect. I should mention this in the commit log.

-- 
MST

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Johannes Berg]

On Fri, 2026-10-16 at 05:47 -0400, Michael S. Tsirkin wrote:
> > > 
> > Right, but virtio_net_hdr_to_skb() cannot return 1, only 0 on success
> > and -ERROR on failure?
> 
> After this patchset, it can, to signal slow path software checksum.
> I'm changing callers first so that changing the function itself
> does not break bisect. I should mention this in the commit log.

Oh, OK, that I clearly missed, but also was only CC'ed on patches 2 and
3 :)

johannes

Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

[Michael S. Tsirkin]

On Fri, Oct 16, 2026 at 11:49:14AM +0200, Johannes Berg wrote:
> On Fri, 2026-10-16 at 05:47 -0400, Michael S. Tsirkin wrote:
> > > > 
> > > Right, but virtio_net_hdr_to_skb() cannot return 1, only 0 on success
> > > and -ERROR on failure?
> > 
> > After this patchset, it can, to signal slow path software checksum.
> > I'm changing callers first so that changing the function itself
> > does not break bisect. I should mention this in the commit log.
> 
> Oh, OK, that I clearly missed, but also was only CC'ed on patches 2 and
> 3 :)
> 
> johannes

Right, I am trying not to spam too widely.
Indeed, this is why commit log should explain.

-- 
MST