From 4b71b3a9e37d06da2ecc48e06eea7e4a4ae1cfe9 Mon Sep 17 00:00:00 2001
From: Fam Zheng <famz@redhat.com>
Date: Thu, 18 May 2017 09:21:20 +0200
Subject: [PATCH 07/18] serial: poll the serial console with G_IO_HUP
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RH-Author: Fam Zheng <famz@redhat.com>
Message-id: <20170518092131.16571-8-famz@redhat.com>
Patchwork-id: 75297
O-Subject: [RHEL-7.4 qemu-kvm PATCH v3 07/18] serial: poll the serial console with G_IO_HUP
Bugzilla: 1451470
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>

From: Roger Pau Monne <roger.pau@citrix.com>

On FreeBSD polling a master pty while the other end is not connected
with G_IO_OUT only results in an endless wait. This is different from
the Linux behaviour, that returns immediately. In order to demonstrate
this, I have the following example code:

http://xenbits.xen.org/people/royger/test_poll.c

When executed on Linux:

$ ./test_poll
In callback

On FreeBSD instead, the callback never gets called:

$ ./test_poll

So, in order to workaround this, poll the source with G_IO_HUP (which
makes the code behave the same way on both Linux and FreeBSD).

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Cc: Michael Tokarev <mjt@tls.msk.ru>
Cc: "Andreas Färber" <afaerber@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: xen-devel@lists.xenproject.org
[Add hw/char/cadence_uart.c too. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

(cherry picked from commit e02bc6de30c44fd668dc0d6e1cd1804f2eed3ed3)
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

Conflicts:
	hw/char/cadence_uart.c

Downstream doesn't use qemu_chr_fe_add_watch because we don't have
38acd64b1c etc.

	monitor.c

The changed line is different because we don't have 6cff3e8594 (monitor:
protect outbuf and mux_out with mutex).
---
 hw/char/serial.c         | 2 +-
 hw/char/virtio-console.c | 3 ++-
 hw/usb/redirect.c        | 2 +-
 monitor.c                | 2 +-
 4 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/hw/char/serial.c b/hw/char/serial.c
index e020b0e..add4738 100644
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -246,7 +246,7 @@ static gboolean serial_xmit(GIOChannel *chan, GIOCondition cond, void *opaque)
         serial_receive1(s, &s->tsr, 1);
     } else if (qemu_chr_fe_write(s->chr, &s->tsr, 1) != 1) {
         if (s->tsr_retry >= 0 && s->tsr_retry < MAX_XMIT_RETRY &&
-            qemu_chr_fe_add_watch(s->chr, G_IO_OUT, serial_xmit, s) > 0) {
+            qemu_chr_fe_add_watch(s->chr, G_IO_OUT|G_IO_HUP, serial_xmit, s) > 0) {
             s->tsr_retry++;
             return FALSE;
         }
diff --git a/hw/char/virtio-console.c b/hw/char/virtio-console.c
index 1b01dcd..69dd95a 100644
--- a/hw/char/virtio-console.c
+++ b/hw/char/virtio-console.c
@@ -66,7 +66,8 @@ static ssize_t flush_buf(VirtIOSerialPort *port,
         if (!k->is_console) {
             virtio_serial_throttle_port(port, true);
             if (!vcon->watch) {
-                vcon->watch = qemu_chr_fe_add_watch(vcon->chr, G_IO_OUT,
+                vcon->watch = qemu_chr_fe_add_watch(vcon->chr,
+                                                    G_IO_OUT|G_IO_HUP,
                                                     chr_write_unblocked, vcon);
             }
         }
diff --git a/hw/usb/redirect.c b/hw/usb/redirect.c
index e3b9f32..3fe2106 100644
--- a/hw/usb/redirect.c
+++ b/hw/usb/redirect.c
@@ -284,7 +284,7 @@ static int usbredir_write(void *priv, uint8_t *data, int count)
     r = qemu_chr_fe_write(dev->cs, data, count);
     if (r < count) {
         if (!dev->watch) {
-            dev->watch = qemu_chr_fe_add_watch(dev->cs, G_IO_OUT,
+            dev->watch = qemu_chr_fe_add_watch(dev->cs, G_IO_OUT|G_IO_HUP,
                                                usbredir_write_unblocked, dev);
         }
         if (r < 0) {
diff --git a/monitor.c b/monitor.c
index 1b28ff3..393a508 100644
--- a/monitor.c
+++ b/monitor.c
@@ -300,7 +300,7 @@ void monitor_flush(Monitor *mon)
             mon->outbuf = tmp;
         }
         if (mon->watch == 0) {
-            mon->watch = qemu_chr_fe_add_watch(mon->chr, G_IO_OUT,
+            mon->watch = qemu_chr_fe_add_watch(mon->chr, G_IO_OUT|G_IO_HUP,
                                                monitor_unblocked, mon);
         }
     }
-- 
1.8.3.1