| Message ID | 358f8d52-fd88-ad2e-87e2-c64bfa516a58@sberdevices.ru (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
| Series | virtio/vsock: use SO_RCVLOWAT to set POLLIN/POLLRDNORM | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessed tree name to be net-next |
| netdev/fixes_present | success | Fixes tag not required for -next series |
| netdev/subject_prefix | success | Link |
| netdev/cover_letter | success | Series has a cover letter |
| netdev/patch_count | success | Link |
| netdev/header_inline | success | No static functions without inline keyword in header files |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/cc_maintainers | success | CCed 9 of 9 maintainers |
| netdev/build_clang | success | Errors and warnings before: 0 this patch: 0 |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Signed-off-by tag matches author and committer |
| netdev/check_selftest | success | No net selftest shell script |
| netdev/verify_fixes | success | No Fixes tag |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 8 lines checked |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/source_inline | success | Was 0 now: 0 |
On Mon, Jul 18, 2022 at 08:17:31AM +0000, Arseniy Krasnov wrote: >This callback controls setting of POLLIN,POLLRDNORM output bits >of poll() syscall,but in some cases,it is incorrectly to set it, >when socket has at least 1 bytes of available data. Use 'target' >which is already exists and equal to sk_rcvlowat in this case. > >Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >--- > net/vmw_vsock/virtio_transport_common.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > >diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >index ec2c2afbf0d0..591908740992 100644 >--- a/net/vmw_vsock/virtio_transport_common.c >+++ b/net/vmw_vsock/virtio_transport_common.c >@@ -634,7 +634,7 @@ virtio_transport_notify_poll_in(struct vsock_sock *vsk, > size_t target, > bool *data_ready_now) > { >- if (vsock_stream_has_data(vsk)) >+ if (vsock_stream_has_data(vsk) >= target) > *data_ready_now = true; > else > *data_ready_now = false; Perhaps we can take the opportunity to clean up the code in this way: *data_ready_now = vsock_stream_has_data(vsk) >= target; Anyway, I think we also need to fix the other transports (vmci and hyperv), what do you think? Thanks, Stefano
On 19.07.2022 15:48, Stefano Garzarella wrote: > On Mon, Jul 18, 2022 at 08:17:31AM +0000, Arseniy Krasnov wrote: >> This callback controls setting of POLLIN,POLLRDNORM output bits >> of poll() syscall,but in some cases,it is incorrectly to set it, >> when socket has at least 1 bytes of available data. Use 'target' >> which is already exists and equal to sk_rcvlowat in this case. >> >> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >> --- >> net/vmw_vsock/virtio_transport_common.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >> index ec2c2afbf0d0..591908740992 100644 >> --- a/net/vmw_vsock/virtio_transport_common.c >> +++ b/net/vmw_vsock/virtio_transport_common.c >> @@ -634,7 +634,7 @@ virtio_transport_notify_poll_in(struct vsock_sock *vsk, >> size_t target, >> bool *data_ready_now) >> { >> - if (vsock_stream_has_data(vsk)) >> + if (vsock_stream_has_data(vsk) >= target) >> *data_ready_now = true; >> else >> *data_ready_now = false; > > Perhaps we can take the opportunity to clean up the code in this way: > > *data_ready_now = vsock_stream_has_data(vsk) >= target; Ack > > Anyway, I think we also need to fix the other transports (vmci and hyperv), what do you think? For vmci it is look clear to fix it. For hyperv i need to check it more, because it already uses some internal target value. > > Thanks, > Stefano >
On Wed, Jul 20, 2022 at 05:38:03AM +0000, Arseniy Krasnov wrote: >On 19.07.2022 15:48, Stefano Garzarella wrote: >> On Mon, Jul 18, 2022 at 08:17:31AM +0000, Arseniy Krasnov wrote: >>> This callback controls setting of POLLIN,POLLRDNORM output bits >>> of poll() syscall,but in some cases,it is incorrectly to set it, >>> when socket has at least 1 bytes of available data. Use 'target' >>> which is already exists and equal to sk_rcvlowat in this case. >>> >>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >>> --- >>> net/vmw_vsock/virtio_transport_common.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >>> index ec2c2afbf0d0..591908740992 100644 >>> --- a/net/vmw_vsock/virtio_transport_common.c >>> +++ b/net/vmw_vsock/virtio_transport_common.c >>> @@ -634,7 +634,7 @@ virtio_transport_notify_poll_in(struct vsock_sock *vsk, >>> size_t target, >>> bool *data_ready_now) >>> { >>> - if (vsock_stream_has_data(vsk)) >>> + if (vsock_stream_has_data(vsk) >= target) >>> *data_ready_now = true; >>> else >>> *data_ready_now = false; >> >> Perhaps we can take the opportunity to clean up the code in this way: >> >> *data_ready_now = vsock_stream_has_data(vsk) >= target; >Ack >> >> Anyway, I think we also need to fix the other transports (vmci and hyperv), what do you think? >For vmci it is look clear to fix it. For hyperv i need to check it more, because it already >uses some internal target value. Yep, I see. Maybe you can pass `target` to hvs_channel_readable() and use it as parameter of HVS_PKT_LEN(). @Dexuan what do you think? Thanks, Stefano
> From: Stefano Garzarella <sgarzare@redhat.com> > Sent: Wednesday, July 20, 2022 1:23 AM > ... > On Wed, Jul 20, 2022 at 05:38:03AM +0000, Arseniy Krasnov wrote: > >On 19.07.2022 15:48, Stefano Garzarella wrote: > >> On Mon, Jul 18, 2022 at 08:17:31AM +0000, Arseniy Krasnov wrote: > >>> This callback controls setting of POLLIN,POLLRDNORM output bits > >>> of poll() syscall,but in some cases,it is incorrectly to set it, > >>> when socket has at least 1 bytes of available data. Use 'target' > >>> which is already exists and equal to sk_rcvlowat in this case. > >>> > >>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> > >>> --- > >>> net/vmw_vsock/virtio_transport_common.c | 2 +- > >>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>> > >>> diff --git a/net/vmw_vsock/virtio_transport_common.c > b/net/vmw_vsock/virtio_transport_common.c > >>> index ec2c2afbf0d0..591908740992 100644 > >>> --- a/net/vmw_vsock/virtio_transport_common.c > >>> +++ b/net/vmw_vsock/virtio_transport_common.c > >>> @@ -634,7 +634,7 @@ virtio_transport_notify_poll_in(struct vsock_sock > *vsk, > >>> size_t target, > >>> bool *data_ready_now) > >>> { > >>> - if (vsock_stream_has_data(vsk)) > >>> + if (vsock_stream_has_data(vsk) >= target) > >>> *data_ready_now = true; > >>> else > >>> *data_ready_now = false; > >> > >> Perhaps we can take the opportunity to clean up the code in this way: > >> > >> *data_ready_now = vsock_stream_has_data(vsk) >= target; > >Ack > >> > >> Anyway, I think we also need to fix the other transports (vmci and hyperv), > >> what do you think? > >For vmci it is look clear to fix it. For hyperv i need to check it more, because it > > already uses some internal target value. > > Yep, I see. Maybe you can pass `target` to hvs_channel_readable() and > use it as parameter of HVS_PKT_LEN(). > > @Dexuan what do you think? > > Thanks, > Stefano Can we return "not supported" to set_rcvlowat for Hyper-V vsock? :-) For Hyper-V vsock, it's easy to tell if there is at least 1 byte to read: please refer to hvs_channel_readable(), but it's difficult to figure out exactly how many bytes can be read. In hvs_channel_readable(), hv_get_bytes_to_read() returns the total bytes of 0, 1 or multiple Hyper-V vsock packets: each packet has a 24-byte header (see HVS_HEADER_LEN), the payload, some padding bytes (if the payload length is not a multiple of 8), and 8 trailing useless bytes. It's hard to get the total payload length because there is no API in include/linux/hyperv.h, drivers/hv/channel.c and drivers/hv/ring_buffer.c that allows us to peek at the data in the VMBus channel's ringbuffer. We could add such a "peek" API in drivers/hv/channel.c (see the non-peek version of the APIs in hvs_stream_dequeue(): hv_pkt_iter_first() and hv_pkt_iter_next()), and examine the whole ringbuffe to figure out the exact total payload length, but I feel it may not be worth the non-trivial complexity just to be POSIX-compliant -- nobody ever complained about this for the past 5 years :-) So I'm wondering if we should allow Hyper-V vsock to not support the set_rcvlowat op? Thanks, -- Dexuan
On 20.07.2022 21:54, Dexuan Cui wrote: >> From: Stefano Garzarella <sgarzare@redhat.com> >> Sent: Wednesday, July 20, 2022 1:23 AM >> ... >> On Wed, Jul 20, 2022 at 05:38:03AM +0000, Arseniy Krasnov wrote: >>> On 19.07.2022 15:48, Stefano Garzarella wrote: >>>> On Mon, Jul 18, 2022 at 08:17:31AM +0000, Arseniy Krasnov wrote: >>>>> This callback controls setting of POLLIN,POLLRDNORM output bits >>>>> of poll() syscall,but in some cases,it is incorrectly to set it, >>>>> when socket has at least 1 bytes of available data. Use 'target' >>>>> which is already exists and equal to sk_rcvlowat in this case. >>>>> >>>>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >>>>> --- >>>>> net/vmw_vsock/virtio_transport_common.c | 2 +- >>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>> >>>>> diff --git a/net/vmw_vsock/virtio_transport_common.c >> b/net/vmw_vsock/virtio_transport_common.c >>>>> index ec2c2afbf0d0..591908740992 100644 >>>>> --- a/net/vmw_vsock/virtio_transport_common.c >>>>> +++ b/net/vmw_vsock/virtio_transport_common.c >>>>> @@ -634,7 +634,7 @@ virtio_transport_notify_poll_in(struct vsock_sock >> *vsk, >>>>> size_t target, >>>>> bool *data_ready_now) >>>>> { >>>>> - if (vsock_stream_has_data(vsk)) >>>>> + if (vsock_stream_has_data(vsk) >= target) >>>>> *data_ready_now = true; >>>>> else >>>>> *data_ready_now = false; >>>> >>>> Perhaps we can take the opportunity to clean up the code in this way: >>>> >>>> *data_ready_now = vsock_stream_has_data(vsk) >= target; >>> Ack >>>> >>>> Anyway, I think we also need to fix the other transports (vmci and hyperv), >>>> what do you think? >>> For vmci it is look clear to fix it. For hyperv i need to check it more, because it >>> already uses some internal target value. >> >> Yep, I see. Maybe you can pass `target` to hvs_channel_readable() and >> use it as parameter of HVS_PKT_LEN(). >> >> @Dexuan what do you think? >> >> Thanks, >> Stefano > > Can we return "not supported" to set_rcvlowat for Hyper-V vsock? :-) > > For Hyper-V vsock, it's easy to tell if there is at least 1 byte to read: > please refer to hvs_channel_readable(), but it's difficult to figure out > exactly how many bytes can be read. > > In hvs_channel_readable(), hv_get_bytes_to_read() returns the total > bytes of 0, 1 or multiple Hyper-V vsock packets: each packet has a > 24-byte header (see HVS_HEADER_LEN), the payload, some padding > bytes (if the payload length is not a multiple of 8), and 8 trailing > useless bytes. > > It's hard to get the total payload length because there is no API in > include/linux/hyperv.h, drivers/hv/channel.c and > drivers/hv/ring_buffer.c that allows us to peek at the data in the > VMBus channel's ringbuffer. > > We could add such a "peek" API in drivers/hv/channel.c (see the > non-peek version of the APIs in hvs_stream_dequeue(): > hv_pkt_iter_first() and hv_pkt_iter_next()), and examine the whole > ringbuffe to figure out the exact total payload length, but I feel it may > not be worth the non-trivial complexity just to be POSIX-compliant -- > nobody ever complained about this for the past 5 years :-) So I'm > wondering if we should allow Hyper-V vsock to not support the > set_rcvlowat op? I see, i can prepare patch for this in this patchset in v2. Call to set SO_RCVLOWAT for Hyper-V transport will return EOPNOTSUPP. Thank You > > Thanks, > -- Dexuan >
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index ec2c2afbf0d0..591908740992 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -634,7 +634,7 @@ virtio_transport_notify_poll_in(struct vsock_sock *vsk, size_t target, bool *data_ready_now) { - if (vsock_stream_has_data(vsk)) + if (vsock_stream_has_data(vsk) >= target) *data_ready_now = true; else *data_ready_now = false;
This callback controls setting of POLLIN,POLLRDNORM output bits of poll() syscall,but in some cases,it is incorrectly to set it, when socket has at least 1 bytes of available data. Use 'target' which is already exists and equal to sk_rcvlowat in this case. Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> --- net/vmw_vsock/virtio_transport_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)