On Tue, Dec 12, 2023 at 06:59:03PM +0300, Arseniy Krasnov wrote: > > > On 12.12.2023 18:54, Michael S. Tsirkin wrote: > > On Tue, Dec 12, 2023 at 12:16:54AM +0300, Arseniy Krasnov wrote: > >> Hello, > >> > >> DESCRIPTION > >> > >> This patchset fixes old problem with hungup of both rx/tx sides and adds > >> test for it. This happens due to non-default SO_RCVLOWAT value and > >> deferred credit update in virtio/vsock. Link to previous old patchset: > >> https://lore.kernel.org/netdev/39b2e9fd-601b-189d-39a9-914e5574524c@xxxxxxxxxxxxxx/ > > > > > > Patchset: > > > > Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > > Thanks! > > > > > > > But I worry whether we actually need 3/8 in net not in net-next. > > Because of "Fixes" tag ? I think this problem is not critical and reproducible > only in special cases, but i'm not familiar with netdev process so good, so I don't > have strong opinion. I guess @Stefano knows better. > > Thanks, Arseniy Fixes means "if you have that other commit then you need this commit too". I think as a minimum you need to rearrange patches to make the fix go in first. We don't want a regression followed by a fix. > > > > Thanks! > > > >> Here is what happens step by step: > >> > >> TEST > >> > >> INITIAL CONDITIONS > >> > >> 1) Vsock buffer size is 128KB. > >> 2) Maximum packet size is also 64KB as defined in header (yes it is > >> hardcoded, just to remind about that value). > >> 3) SO_RCVLOWAT is default, e.g. 1 byte. > >> > >> > >> STEPS > >> > >> SENDER RECEIVER > >> 1) sends 128KB + 1 byte in a > >> single buffer. 128KB will > >> be sent, but for 1 byte > >> sender will wait for free > >> space at peer. Sender goes > >> to sleep. > >> > >> > >> 2) reads 64KB, credit update not sent > >> 3) sets SO_RCVLOWAT to 64KB + 1 > >> 4) poll() -> wait forever, there is > >> only 64KB available to read. > >> > >> So in step 4) receiver also goes to sleep, waiting for enough data or > >> connection shutdown message from the sender. Idea to fix it is that rx > >> kicks tx side to continue transmission (and may be close connection) > >> when rx changes number of bytes to be woken up (e.g. SO_RCVLOWAT) and > >> this value is bigger than number of available bytes to read. > >> > >> I've added small test for this, but not sure as it uses hardcoded value > >> for maximum packet length, this value is defined in kernel header and > >> used to control deferred credit update. And as this is not available to > >> userspace, I can't control test parameters correctly (if one day this > >> define will be changed - test may become useless). > >> > >> Head for this patchset is: > >> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=021b0c952f226236f2edf89c737efb9a28d1422d > >> > >> Link to v1: > >> https://lore.kernel.org/netdev/20231108072004.1045669-1-avkrasnov@xxxxxxxxxxxxxxxxx/ > >> Link to v2: > >> https://lore.kernel.org/netdev/20231119204922.2251912-1-avkrasnov@xxxxxxxxxxxxxxxxx/ > >> Link to v3: > >> https://lore.kernel.org/netdev/20231122180510.2297075-1-avkrasnov@xxxxxxxxxxxxxxxxx/ > >> Link to v4: > >> https://lore.kernel.org/netdev/20231129212519.2938875-1-avkrasnov@xxxxxxxxxxxxxxxxx/ > >> Link to v5: > >> https://lore.kernel.org/netdev/20231130130840.253733-1-avkrasnov@xxxxxxxxxxxxxxxxx/ > >> Link to v6: > >> https://lore.kernel.org/netdev/20231205064806.2851305-1-avkrasnov@xxxxxxxxxxxxxxxxx/ > >> Link to v7: > >> https://lore.kernel.org/netdev/20231206211849.2707151-1-avkrasnov@xxxxxxxxxxxxxxxxx/ > >> > >> Changelog: > >> v1 -> v2: > >> * Patchset rebased and tested on new HEAD of net-next (see hash above). > >> * New patch is added as 0001 - it removes return from SO_RCVLOWAT set > >> callback in 'af_vsock.c' when transport callback is set - with that > >> we can set 'sk_rcvlowat' only once in 'af_vsock.c' and in future do > >> not copy-paste it to every transport. It was discussed in v1. > >> * See per-patch changelog after ---. > >> v2 -> v3: > >> * See changelog after --- in 0003 only (0001 and 0002 still same). > >> v3 -> v4: > >> * Patchset rebased and tested on new HEAD of net-next (see hash above). > >> * See per-patch changelog after ---. > >> v4 -> v5: > >> * Change patchset tag 'RFC' -> 'net-next'. > >> * See per-patch changelog after ---. > >> v5 -> v6: > >> * New patch 0003 which sends credit update during reading bytes from > >> socket. > >> * See per-patch changelog after ---. > >> v6 -> v7: > >> * Patchset rebased and tested on new HEAD of net-next (see hash above). > >> * See per-patch changelog after ---. > >> v7 -> v8: > >> * See per-patch changelog after ---. > >> > >> Arseniy Krasnov (4): > >> vsock: update SO_RCVLOWAT setting callback > >> virtio/vsock: send credit update during setting SO_RCVLOWAT > >> virtio/vsock: fix logic which reduces credit update messages > >> vsock/test: two tests to check credit update logic > >> > >> drivers/vhost/vsock.c | 1 + > >> include/linux/virtio_vsock.h | 1 + > >> include/net/af_vsock.h | 2 +- > >> net/vmw_vsock/af_vsock.c | 9 +- > >> net/vmw_vsock/hyperv_transport.c | 4 +- > >> net/vmw_vsock/virtio_transport.c | 1 + > >> net/vmw_vsock/virtio_transport_common.c | 43 +++++- > >> net/vmw_vsock/vsock_loopback.c | 1 + > >> tools/testing/vsock/vsock_test.c | 175 ++++++++++++++++++++++++ > >> 9 files changed, 229 insertions(+), 8 deletions(-) > >> > >> -- > >> 2.25.1 > >
