On 12.12.2023 19:12, Michael S. Tsirkin wrote: > 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. I see, ok, @Stefano WDYT? I think rearrange doesn't break anything, because this patch fixes problem that is not related with the new patches from this patchset. Thanks, Arseniy > >>> >>> 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 >>> >
