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hv_sock: Report EOF instead of -EIO for FIN

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Commit f0c5827d07 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: f0c5827d07 ("hv_sock: Return the readable bytes in hvs_stream_has_data()")
Cc: stable@vger.kernel.org
Reported-by: Ben Hillis <Ben.Hillis@microsoft.com>
Reported-by: Mitchell Levy <levymitchell0@gmail.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260416191433.840637-1-decui@microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Dexuan Cui 2026-04-16 12:14:33 -07:00 committed by Jakub Kicinski
parent b94769eb2f
commit f631529589
1 changed files with 16 additions and 4 deletions
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20
net/vmw_vsock/hyperv_transport.c
View File

@ -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)