[Qemu-stable] [PATCH 001/156] char: restore read callback on a reattached (hotplug) chardev

[Michael Roth]

From: Gal Hammer <address@hidden>

Fix a bug that was introduced in commit 386a5a1e. A removal of a device
set the chr handlers to NULL. However when the device is plugged back,
its read callback is not restored so data can't be transferred from the
host to the guest (e.g. via the virtio-serial port).

https://bugzilla.redhat.com/show_bug.cgi?id=1027181

Signed-off-by: Gal Hammer <address@hidden>
Signed-off-by: Gerd Hoffmann <address@hidden>
(cherry picked from commit ac1b84dd1e020648db82a99260891aa982d1142c)
Signed-off-by: Michael Roth <address@hidden>
---
 qemu-char.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index e00f84c..1c0d648 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -213,7 +213,7 @@ void qemu_chr_add_handlers(CharDriverState *s,
     s->chr_read = fd_read;
     s->chr_event = fd_event;
     s->handler_opaque = opaque;
-    if (s->chr_update_read_handler)
+    if (fe_open && s->chr_update_read_handler)
         s->chr_update_read_handler(s);
 
     if (!s->explicit_fe_open) {
@@ -1136,13 +1136,14 @@ static void pty_chr_state(CharDriverState *chr, int 
connected)
         if (!s->connected) {
             s->connected = 1;
             qemu_chr_be_generic_open(chr);
+        }
+        if (!chr->fd_in_tag) {
             chr->fd_in_tag = io_add_watch_poll(s->fd, pty_chr_read_poll,
                                                pty_chr_read, chr);
         }
     }
 }
 
-
 static void pty_chr_close(struct CharDriverState *chr)
 {
     PtyCharDriver *s = chr->opaque;
@@ -2510,6 +2511,17 @@ static void tcp_chr_connect(void *opaque)
     qemu_chr_be_generic_open(chr);
 }
 
+static void tcp_chr_update_read_handler(CharDriverState *chr)
+{
+    TCPCharDriver *s = chr->opaque;
+
+    remove_fd_in_watch(chr);
+    if (s->chan) {
+        chr->fd_in_tag = io_add_watch_poll(s->chan, tcp_chr_read_poll,
+                                           tcp_chr_read, chr);
+    }
+}
+
 #define IACSET(x,a,b,c) x[0] = a; x[1] = b; x[2] = c;
 static void tcp_chr_telnet_init(int fd)
 {
@@ -2665,6 +2677,7 @@ static CharDriverState *qemu_chr_open_socket_fd(int fd, 
bool do_nodelay,
     chr->get_msgfd = tcp_get_msgfd;
     chr->chr_add_client = tcp_chr_add_client;
     chr->chr_add_watch = tcp_chr_add_watch;
+    chr->chr_update_read_handler = tcp_chr_update_read_handler;
     /* be isn't opened until we get a connection */
     chr->explicit_be_open = true;
 
-- 
1.9.1