On 02/24, Magnus Karlsson wrote: > On Sat, 22 Feb 2025 at 10:18, Wang Liang <wangliang74@xxxxxxxxxx> wrote: > > > > When the cq reservation is failed, the error code is not set which is > > initialized to zero in __xsk_generic_xmit(). That means the packet is not > > send successfully but sendto() return ok. > > > > Set the error code and make xskq_prod_reserve_addr()/xskq_prod_reserve() > > return values more meaningful when the queue is full. > > Hi Wang, > > I agree that this would have been a really good idea if it was > implemented from day one, but now I do not dare to change this since > it would be changing the uapi. Let us say you have the following quite > common code snippet for sending a packet with AF_XDP in skb mode: > > err = sendmsg(); > if (err && err != -EAGAIN && err != -EBUSY) > goto die_due_to_error; > continue with code > > This code would with your change go and die suddenly when the > completion ring is full instead of working. Maybe there is a piece of > code that cleans the completion ring after these lines of code and > next time sendmsg() is called, the packet will get sent, so the > application used to work. > > So I say: let us not do this. But if anyone has another opinion, please share. Can we return -EBUSY from this 'if (xsk_cq_reserve_addr_locked())' case as well?
