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    Subject[RFC PATCH v2 0/6] Improve SOCK_SEQPACKET receive logic
    Date
    	This patchset modifies receive logic for SOCK_SEQPACKET.
    Difference between current implementation and this version is that
    now reader is woken up when there is at least one RW packet in rx
    queue of socket and data is copied to user's buffer, while merged
    approach wake up user only when whole message is received and kept
    in queue. New implementation has several advantages:
    1) There is no limit for message length. Merged approach requires
    that length must be smaller than 'peer_buf_alloc', otherwise
    transmission will stuck.
    2) There is no need to keep whole message in queue, thus no
    'kmalloc()' memory will be wasted until EOR is received.

    Also new approach has some feature: as fragments of message
    are copied until EOR is received, it is possible that part of
    message will be already in user's buffer, while rest of message
    still not received. And if user will be interrupted by signal or
    timeout with part of message in buffer, it will exit receive loop,
    leaving rest of message in queue. To solve this problem special
    callback was added to transport: it is called when user was forced
    to leave exit loop and tells transport to drop any packet until
    EOR met. When EOR is found, this mode is disabled and normal packet
    processing started. Note, that when 'drop until EOR' mode is on,
    incoming packets still inserted in queue, reader will be woken up,
    tries to copy data, but nothing will be copied until EOR found.
    It was possible to drain such unneeded packets it rx work without
    kicking user, but implemented way is simplest. Anyway, i think
    such cases are rare.

    New test also added - it tries to copy to invalid user's
    buffer.

    Arseny Krasnov (16):
    af_vsock/virtio/vsock: change seqpacket receive logic
    af_vsock/virtio/vsock: remove 'seqpacket_has_data' callback
    virtio/vsock: remove 'msg_count' based logic
    af_vsock/virtio/vsock: add 'seqpacket_drop()' callback
    virtio/vsock: remove record size limit for SEQPACKET
    vsock_test: SEQPACKET read to broken buffer

    drivers/vhost/vsock.c | 2 +-
    include/linux/virtio_vsock.h | 7 +-
    include/net/af_vsock.h | 4 +-
    net/vmw_vsock/af_vsock.c | 44 ++++----
    net/vmw_vsock/virtio_transport.c | 2 +-
    net/vmw_vsock/virtio_transport_common.c | 103 ++++++++-----------
    net/vmw_vsock/vsock_loopback.c | 2 +-
    tools/testing/vsock/vsock_test.c | 120 ++++++++++++++++++++++
    8 files changed, 193 insertions(+), 91 deletions(-)

    v1 -> v2:
    Patches reordered and reorganized.

    Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
    ---
    cv.txt | 0
    1 file changed, 0 insertions(+), 0 deletions(-)
    create mode 100644 cv.txt

    diff --git a/cv.txt b/cv.txt
    new file mode 100644
    index 000000000000..e69de29bb2d1
    --
    2.25.1

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