On 5/7/25 10:26, Stefano Garzarella wrote: > On Wed, 7 May 2025 at 00:47, Michal Luczaj <mhal@xxxxxxx> wrote: >> >> On 5/6/25 11:46, Stefano Garzarella wrote: >>> On Tue, 6 May 2025 at 11:43, Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote: >>>> >>>> On Thu, May 01, 2025 at 10:05:24AM +0200, Michal Luczaj wrote: >>>>> There was an issue with SO_LINGER: instead of blocking until all queued >>>>> messages for the socket have been successfully sent (or the linger timeout >>>>> has been reached), close() would block until packets were handled by the >>>>> peer. >>>> >>>> This is a new behaviour that only new kernels will follow, so I think >>>> it is better to add a new test instead of extending a pre-existing test >>>> that we described as "SOCK_STREAM SO_LINGER null-ptr-deref". >>>> >>>> The old test should continue to check the null-ptr-deref also for old >>>> kernels, while the new test will check the new behaviour, so we can skip >>>> the new test while testing an old kernel. >> >> Right, I'll split it. >> >>> I also saw that we don't have any test to verify that actually the >>> lingering is working, should we add it since we are touching it? >> >> Yeah, I agree we should. Do you have any suggestion how this could be done >> reliably? > > Can we play with SO_VM_SOCKETS_BUFFER_SIZE like in credit-update tests? > > One peer can set it (e.g. to 1k), accept the connection, but without > read anything. The other peer can set the linger timeout, send more > bytes than the buffer size set by the receiver. > At this point the extra bytes should stay on the sender socket buffer, > so we can do the close() and it should time out, and we can check if > it happens. > > WDYT? Haven't we discussed this approach in [1]? I've reported that I can't make it work. But maybe I'm misunderstanding something, please see the code below. [1]: https://lore.kernel.org/netdev/df2d51fd-03e7-477f-8aea-938446f47864@xxxxxxx/ import termios, time from socket import * SIOCOUTQ = termios.TIOCOUTQ VMADDR_CID_LOCAL = 1 SZ = 1024 def set_linger(s, timeout): optval = (timeout << 32) | 1 s.setsockopt(SOL_SOCKET, SO_LINGER, optval) assert s.getsockopt(SOL_SOCKET, SO_LINGER) == optval def set_bufsz(s, size): s.setsockopt(AF_VSOCK, SO_VM_SOCKETS_BUFFER_SIZE, size) assert s.getsockopt(AF_VSOCK, SO_VM_SOCKETS_BUFFER_SIZE) == size def check_lingering(addr): lis = socket(AF_VSOCK, SOCK_STREAM) lis.bind(addr) lis.listen() set_bufsz(lis, SZ) s = socket(AF_VSOCK, SOCK_STREAM) set_linger(s, 5) s.connect(lis.getsockname()) p, _ = lis.accept() s.send(b'x') p.recv(1) print("sending...") s.send(b'x' * (SZ+1)) # blocks print("sent") print("closing...") ts = time.time() s.close() print("done in %ds" % (time.time() - ts)) check_lingering((VMADDR_CID_LOCAL, 1234))
