[Qemu-devel] [PATCH RFC] char: fix avail_connections init in qemu_chr_open_eventfd()

[David Marchand <david.marchand@6wind.com>]

Hello, 

First of all, this is a pure RFC patch, I did not take too much time to dig into
qemu source code to find the right solution, but since qemu_chr_open_eventfd()
is only used by the code I was looking at, here is a patch.


When trying to use a ivshmem server with qemu, ivshmem init code tries to
create a CharDriverState object for each eventfd retrieved from the server.
To create this object, a call to qemu_chr_open_eventfd() is done.
Right after this, before adding a frontend, qemu_chr_fe_claim_no_fail() is
called.
qemu_chr_open_eventfd() does not set avail_connections to 1, so no frontend can
be associated because qemu_chr_fe_claim_no_fail() makes qemu stop right away.

I suppose this problem comes from 456d60692310e7ac25cf822cc1e98192ad636ece
"qemu-char: Call fe_claim / fe_release when not using qdev chr properties".

Fix this, by setting avail_connections to 1 in qemu_chr_open_eventfd().

Signed-off-by: David Marchand <david.marchand@6wind.com>
---
 qemu-char.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/qemu-char.c b/qemu-char.c
index 30c5a6a..c0adb04 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2492,7 +2492,12 @@ static gboolean tcp_chr_read(GIOChannel *chan, GIOCondition cond, void *opaque)
 #ifndef _WIN32
 CharDriverState *qemu_chr_open_eventfd(int eventfd)
 {
-    return qemu_chr_open_fd(eventfd, eventfd);
+    CharDriverState *chr = qemu_chr_open_fd(eventfd, eventfd);
+
+    if (chr)
+        chr->avail_connections = 1;
+
+    return chr;
 }
 #endif
 
-- 
David Marchand