[Xen-devel] [PATCH v2 3/3] serial: poll the serial console with G_IO_HUP

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

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 Monnà <roger.pau@xxxxxxxxxx>
Cc: Peter Crosthwaite <peter.crosthwaite@xxxxxxxxxx>
Cc: Michael Tokarev <mjt@xxxxxxxxxx>
Cc: "Andreas FÃrber" <afaerber@xxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
---
Changes since v1:
 - Fix other users of qemu_chr_fe_add_watch to use G_IO_HUP.
---
 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 f4d167f..2a2c9e5 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 6c8be0f..38e290a 100644
--- a/hw/char/virtio-console.c
+++ b/hw/char/virtio-console.c
@@ -69,7 +69,8 @@ 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 287a505..06e757d 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 593679a..ae1c539 100644
--- a/monitor.c
+++ b/monitor.c
@@ -304,7 +304,7 @@ 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);
         }
     }
-- 
1.7.7.5 (Apple Git-26)


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