Re: [Qemu-devel] [PATCH] Handle G_IO_HUP in tcp_chr_read for tcp chardev

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jul 01, 2014 at 02:04:38PM +0200, Paolo Bonzini wrote:
> Il 01/07/2014 13:52, Kirill Batuzov ha scritto:
> >Due to GLib limitations it is not possible to create several watches on one
> >channel on Windows hosts. See bug #338943 in GNOME bugzilla for details:
> >https://bugzilla.gnome.org/show_bug.cgi?id=338943
> >
> >Handle G_IO_HUP in tcp_chr_read. It is already watched by corresponding watch.
> >Also remove the second watch with its handler.
> >
> >This reverts commit cdaa86a54b232572bba594bf87a7416e527e460c.
> >("Add G_IO_HUP handler for socket chardev") but keeps its functionality.
> >
> >Cc: Antonios Motakis <a.motakis@virtualopensystems.com>
> >Cc: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
> >Cc: Michael S. Tsirkin <mst@redhat.com>
> >Signed-off-by: Kirill Batuzov <batuzovk@ispras.ru>
> >Signed-off-by: Nikita Belov <zodiac@ispras.ru>
> >---
> >
> >GLib limitation resulted in a bug on Windows host. Steps to reproduce:
> >
> >Start qemu: qemu-system-i386 -qmp tcp:127.0.0.1:4444:server:nowait
> >Connect with telnet: telnet 127.0.0.1 4444
> >Try sending some data from telnet.
> >Expected result: answers from QEMU.
> >Observed result: no answers (actually tcp_chr_read is not called at all).
> 
> I think Michael is on holiday; CCing Gerd.
> 
> Paolo

Not really :)


> >---
> > include/sysemu/char.h |    1 -
> > qemu-char.c           |   27 ++++++---------------------
> > 2 files changed, 6 insertions(+), 22 deletions(-)
> >
> >diff --git a/include/sysemu/char.h b/include/sysemu/char.h
> >index c8b15f9..0bbd631 100644
> >--- a/include/sysemu/char.h
> >+++ b/include/sysemu/char.h
> >@@ -84,7 +84,6 @@ struct CharDriverState {
> >     int avail_connections;
> >     int is_mux;
> >     guint fd_in_tag;
> >-    guint fd_hup_tag;
> >     QemuOpts *opts;
> >     QTAILQ_ENTRY(CharDriverState) next;
> > };
> >diff --git a/qemu-char.c b/qemu-char.c
> >index 51917de..22a9777 100644
> >--- a/qemu-char.c
> >+++ b/qemu-char.c
> >@@ -2673,6 +2673,12 @@ static gboolean tcp_chr_read(GIOChannel *chan, GIOCondition cond, void *opaque)
> >     uint8_t buf[READ_BUF_LEN];
> >     int len, size;
> >
> >+    if (cond & G_IO_HUP) {
> >+        /* connection closed */
> >+        tcp_chr_disconnect(chr);
> >+        return TRUE;
> >+    }
> >+
> >     if (!s->connected || s->max_size <= 0) {
> >         return TRUE;
> >     }
> >@@ -2724,25 +2730,6 @@ CharDriverState *qemu_chr_open_eventfd(int eventfd)
> > }
> > #endif
> >
> >-static gboolean tcp_chr_chan_close(GIOChannel *channel, GIOCondition cond,
> >-                                   void *opaque)
> >-{
> >-    CharDriverState *chr = opaque;
> >-
> >-    if (cond != G_IO_HUP) {
> >-        return FALSE;
> >-    }
> >-
> >-    /* connection closed */
> >-    tcp_chr_disconnect(chr);
> >-    if (chr->fd_hup_tag) {
> >-        g_source_remove(chr->fd_hup_tag);
> >-        chr->fd_hup_tag = 0;
> >-    }
> >-
> >-    return TRUE;
> >-}
> >-
> > static void tcp_chr_connect(void *opaque)
> > {
> >     CharDriverState *chr = opaque;
> >@@ -2752,8 +2739,6 @@ static void tcp_chr_connect(void *opaque)
> >     if (s->chan) {
> >         chr->fd_in_tag = io_add_watch_poll(s->chan, tcp_chr_read_poll,
> >                                            tcp_chr_read, chr);
> >-        chr->fd_hup_tag = g_io_add_watch(s->chan, G_IO_HUP, tcp_chr_chan_close,
> >-                                         chr);
> >     }
> >     qemu_chr_be_generic_open(chr);
> > }
> >