[PULL 3/4] io/channel-socket: Document why we can ignore socket_set_cork() errors

["Daniel P. Berrangé" <berrange@redhat.com>]

From: Peter Maydell <peter.maydell@linaro.org>

In qio_channel_socket_set_cork(), we call socket_set_cork() but
ignore its success/failure return value.  This is OK because we are
implementing qio_channel_set_cork() here, and that function's API
documentation states that the setting is merely a hint.  So even if
setting TCP_CORK on the underlying socket fails for some reason, this
isn't going to be a problem for the caller; correspondingly the
qio_channel_set_cork() function has no error return.

Add a comment in qio_channel_socket_set_cork() explaining why we
don't check for errors.

Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/2254
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 io/channel-socket.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/io/channel-socket.c b/io/channel-socket.c
index ea2ec84108..12773b832c 100644
--- a/io/channel-socket.c
+++ b/io/channel-socket.c
@@ -946,6 +946,12 @@ qio_channel_socket_set_cork(QIOChannel *ioc,
     QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc);
     int v = enabled ? 1 : 0;
 
+    /*
+     * We can ignore the error return from socket_set_cork() because
+     * at the QIO API level set_cork is only a hint, and so
+     * qio_channel_set_cork() can never fail even if it didn't
+     * actually do anything.
+     */
     socket_set_cork(sioc->fd, v);
 }
 
-- 
2.55.0