On Fri, May 08, 2026 at 08:01:17AM -0700, Stanislav Fomichev wrote: > On 05/07, Bobby Eshleman wrote: > > From: Bobby Eshleman <[email protected]> > > > > When a netkit virtual device leases queues from a physical NIC, devmem > > TX bindings created on the netkit device must still result in the dmabuf > > being mapped for dma by the physical device. This patch accomplishes > > this by teaching the bind handler to search for the underlying > > DMA-capable device by looking it up via leased rx queues. The function > > netdev_find_netmem_tx_dev(), used for finding the underlying DMA-capable > > device, can be extended to support other non-netkit NETMEM_TX_NO_DMA > > devices in the future if needed. > > > > Additionally, this patch extends validate_xmit_unreadable_skb() to > > support the netkit case, where the skb is validated twice: once on the > > netkit guest device and again on the physical NIC after BPF redirect or > > ip forwarding. > > > > Signed-off-by: Bobby Eshleman <[email protected]> > > --- > > Changes in v3: > > - Fix validate_xmit_unreadable_skb() bug for non-devmem > > unreadable niovs (should not be dropped) > > - Major simplification of validate_xmit_unreadable_skb() > > - Fix prematurely released lock in bind-tx handler (Jakub) > > > > Changes in v2: > > - In validate_xmit_unreadable_skb() to check netmem_tx mode before > > inspecting frags (Jakub) > > - Lock bind_dev around netdev_queue_get_dma_dev() when bind_dev != > > netdev to fix lockdep (Sashiko) > > --- > > net/core/dev.c | 3 +++ > > net/core/devmem.c | 6 +++-- > > net/core/devmem.h | 9 ++++++-- > > net/core/netdev-genl.c | 63 > > ++++++++++++++++++++++++++++++++++++++++++++++---- > > 4 files changed, 72 insertions(+), 9 deletions(-) > > > > diff --git a/net/core/dev.c b/net/core/dev.c > > index fbe4c328a367..268417c9ef22 100644 > > --- a/net/core/dev.c > > +++ b/net/core/dev.c > > @@ -3999,6 +3999,9 @@ static struct sk_buff > > *validate_xmit_unreadable_skb(struct sk_buff *skb, > > if (dev->netmem_tx == NETMEM_TX_NONE) > > goto out_free; > > > > + if (dev->netmem_tx == NETMEM_TX_NO_DMA) > > + goto out; > > + > > Since this is a good case, maybe fold it into skb_frags_readable check above? > > if (likely(skb_frags_readable() || netmem_tx == NETMEM_TX_NO_DMA)) > > Otherwise it's a bit confusing to have: > > if (xxx) > goto out; > if (yyy) > goto out_free; > if (zzz) > goto out; > > (or, reorder to be out/out/out_free) > > Acked-by: Stanislav Fomichev <[email protected]>
Makes sense, will use the combined conditional. Best, Bobby
