Virtualization - Jul 2023 - [PATCH net-next v3 0/4] virtio/vsock: some updates for MSG_PEEK flag

On Tue, Jul 25, 2023 at 08:29:08PM +0300, Arseniy Krasnov
wrote:
> Hello,
> 
> This patchset does several things around MSG_PEEK flag support. In
> general words it reworks MSG_PEEK test and adds support for this flag
> in SOCK_SEQPACKET logic. Here is per-patch description:
> 
> 1) This is cosmetic change for SOCK_STREAM implementation of MSG_PEEK:
>    1) I think there is no need of "safe" mode walk here as there
is no
>       "unlink" of skbs inside loop (it is MSG_PEEK mode - we
don't change
>       queue).
>    2) Nested while loop is removed: in case of MSG_PEEK we just walk
>       over skbs and copy data from each one. I guess this nested loop
>       even didn't behave as loop - it always executed just for single
>       iteration.
> 
> 2) This adds MSG_PEEK support for SOCK_SEQPACKET. It could be implemented
>    be reworking MSG_PEEK callback for SOCK_STREAM to support SOCK_SEQPACKET
>    also, but I think it will be more simple and clear from potential
>    bugs to implemented it as separate function thus not mixing logics
>    for both types of socket. So I've added it as dedicated function.
> 
> 3) This is reworked MSG_PEEK test for SOCK_STREAM. Previous version just
>    sent single byte, then tried to read it with MSG_PEEK flag, then read
>    it in normal way. New version is more complex: now sender uses buffer
>    instead of single byte and this buffer is initialized with random
>    values. Receiver tests several things:
>    1) Read empty socket with MSG_PEEK flag.
>    2) Read part of buffer with MSG_PEEK flag.
>    3) Read whole buffer with MSG_PEEK flag, then checks that it is same
>       as buffer from 2) (limited by size of buffer from 2) of course).
>    4) Read whole buffer without any flags, then checks that it is same
>       as buffer from 3).
> 
> 4) This is MSG_PEEK test for SOCK_SEQPACKET. It works in the same way
>    as for SOCK_STREAM, except it also checks combination of MSG_TRUNC
>    and MSG_PEEK.
Acked-by: Michael S. Tsirkin <mst at redhat.com>


> Head is:
>
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=a5a91f546444940f3d75e2edf3c53b4d235f0557
> 
> Link to v1:
> https://lore.kernel.org/netdev/20230618062451.79980-1-AVKrasnov at
sberdevices.ru/
> Link to v2:
> https://lore.kernel.org/netdev/20230719192708.1775162-1-AVKrasnov at
sberdevices.ru/
> 
> Changelog:
>  v1 -> v2:
>  * Patchset is rebased on the new HEAD of net-next.
>  * 0001: R-b tag added.
>  * 0003: check return value of 'send()' call. 
>  v2 -> v3:
>  * Patchset is rebased (and tested) on the new HEAD of net-next.
>  * 'RFC' tag is replaced with 'net-next'.
>  * Small refactoring in 0004:
>    '__test_msg_peek_client()' ->
'test_msg_peek_client()'.
>    '__test_msg_peek_server()' ->
'test_msg_peek_server()'.
> 
> Arseniy Krasnov (4):
>   virtio/vsock: rework MSG_PEEK for SOCK_STREAM
>   virtio/vsock: support MSG_PEEK for SOCK_SEQPACKET
>   vsock/test: rework MSG_PEEK test for SOCK_STREAM
>   vsock/test: MSG_PEEK test for SOCK_SEQPACKET
> 
>  net/vmw_vsock/virtio_transport_common.c | 104 +++++++++++++-----
>  tools/testing/vsock/vsock_test.c        | 136 ++++++++++++++++++++++--
>  2 files changed, 208 insertions(+), 32 deletions(-)
> 
> -- 
> 2.25.1