Re: [PATCH net-next v5 4/5] vsock/virtio: coalesce native RX write-space notifications

[sashiko-bot@kernel.org]

> Each received packet can update peer credit and call sk_write_space(). A
> writer cannot consume that credit while the virtio RX worker retains the
> socket lock, so repeated native write-space notifications in one RX batch
> are unnecessary.
> 
> This patch coalesces write-space notifications on the native AF_VSOCK path;
> data-ready remains per-packet here.
> 
> The batching patch establishes batch ownership before its first packet.
> This lets this patch record a pending notification for that packet and
> flush it even if the packet immediately ends the batch. Deliver it while
> holding the socket lock to preserve the callback context of the existing
> receive path. A following patch changes that timing together with
> data-ready handling.
> 
> Capture the native write-space callback before socket publication and
> access it through AF_VSOCK helpers. Sockmap can change the protocol,
> write-space callback, and psock marker without the socket lock. Serialize
> each batch eligibility check with sk_callback_lock; if a packet boundary
> observes a replacement, finish the batch and use the regular per-packet
> path.
> 
> Packets admitted on the native path use the saved native callback at batch
> finish. Reloading a current sockmap callback would not synchronize its
> invocation with teardown; a wrapper seen before teardown need not forward
> the native wakeup after its psock is gone.
> 
> Signed-off-by: Jia Jia <physicalmtea@gmail.com>

Sashiko has reviewed this patch and found no issues.

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