Commit f6315295 authored by Dexuan Cui's avatar Dexuan Cui Committed by Jakub Kicinski
Browse files

hv_sock: Report EOF instead of -EIO for FIN 



Commit f0c5827d unluckily causes a regression for the FIN packet,
and the final read syscall gets an error rather than 0.

Ideally, we would want to fix hvs_channel_readable_payload() so that it
could return 0 in the FIN scenario, but it's not good for the hv_sock
driver to use the VMBus ringbuffer's cached priv_read_index, which is
internal data in the VMBus driver.

Fix the regression in hv_sock by returning 0 rather than -EIO.

Fixes: f0c5827d ("hv_sock: Return the readable bytes in hvs_stream_has_data()")
Cc: stable@vger.kernel.org
Reported-by: default avatarBen Hillis <Ben.Hillis@microsoft.com>
Reported-by: default avatarMitchell Levy <levymitchell0@gmail.com>
Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
Acked-by: default avatarStefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260416191433.840637-1-decui@microsoft.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent b94769eb

net/vmw_vsock/hyperv_transport.c

+16 −4
Original line number Diff line number Diff line
@@ -694,7 +694,6 @@ static ssize_t hvs_stream_enqueue(struct vsock_sock *vsk, struct msghdr *msg, 
static s64 hvs_stream_has_data(struct vsock_sock *vsk)

{

	struct hvsock *hvs = vsk->trans;

	bool need_refill;

	s64 ret;



	if (hvs->recv_data_len > 0)
@@ -702,9 +701,22 @@ static s64 hvs_stream_has_data(struct vsock_sock *vsk) 


	switch (hvs_channel_readable_payload(hvs->chan)) {

	case 1:

		need_refill = !hvs->recv_desc;

		if (!need_refill)

			return -EIO;

		if (hvs->recv_desc) {

			/* Here hvs->recv_data_len is 0, so hvs->recv_desc must

			 * be NULL unless it points to the 0-byte-payload FIN

			 * packet: see hvs_update_recv_data().

			 *

			 * Here all the payload has been dequeued, but

			 * hvs_channel_readable_payload() still returns 1,

			 * because the VMBus ringbuffer's read_index is not

			 * updated for the FIN packet: hvs_stream_dequeue() ->

			 * hv_pkt_iter_next() updates the cached priv_read_index

			 * but has no opportunity to update the read_index in

			 * hv_pkt_iter_close() as hvs_stream_has_data() returns

			 * 0 for the FIN packet, so it won't get dequeued.

			 */

			return 0;

		}



		hvs->recv_desc = hv_pkt_iter_first(hvs->chan);

		if (!hvs->recv_desc)