Re: [Qemu-devel] glib mainloop breaks virtfs

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

On Tue, 06 Sep 2011 13:22:36 +0200, Gerd Hoffmann <kraxel@redhat.com> wrote:
>    Hi,
> 
> virtfs stopped working for me in master, the guest (fedora 15) just 
> hangs at boot when mounting the virtfs filesystems.  Bisecting points to 
> this commit:
> 
> rincewind kraxel ~/projects/qemu ((69e5bb6...)|BISECTING)# git bisect good
> 4d88a2ac8643265108ef1fb47ceee5d7b28e19f2 is the first bad commit
> commit 4d88a2ac8643265108ef1fb47ceee5d7b28e19f2
> Author: Anthony Liguori <aliguori@us.ibm.com>
> Date:   Mon Aug 22 08:12:53 2011 -0500
> 
>      main: switch qemu_set_fd_handler to g_io_add_watch
> 
> cheers,
>    Gerd
> 

The below patch fix the problem for me.

commit 52ed37a201d34a3070b4e2d0f21b5e6cca50352e
Author: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Date:   Wed Sep 7 16:11:03 2011 +0530

    iohandler:  update qemu_fd_set_handler to work with null call back arg
    
    Many users of qemu_fd_set_handler including VirtFS use NULL call back arg.
    Update fd_trampoline and qemu_fd_set_handler to work with NULL call back arg
    
    Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

diff --git a/iohandler.c b/iohandler.c
index 5ef66fb..b803208 100644
--- a/iohandler.c
+++ b/iohandler.c
@@ -93,10 +93,6 @@ static gboolean fd_trampoline(GIOChannel *chan, GIOCondition cond, gpointer opaq
 {
     IOTrampoline *tramp = opaque;
 
-    if (tramp->opaque == NULL) {
-        return FALSE;
-    }
-
     if ((cond & G_IO_IN) && tramp->fd_read) {
         tramp->fd_read(tramp->opaque);
     }
@@ -113,6 +109,7 @@ int qemu_set_fd_handler(int fd,
                         IOHandler *fd_write,
                         void *opaque)
 {
+    GIOCondition cond = 0;
     static IOTrampoline fd_trampolines[FD_SETSIZE];
     IOTrampoline *tramp = &fd_trampolines[fd];
 
@@ -121,25 +118,21 @@ int qemu_set_fd_handler(int fd,
         g_source_remove(tramp->tag);
     }
 
-    if (opaque) {
-        GIOCondition cond = 0;
-
-        tramp->fd_read = fd_read;
-        tramp->fd_write = fd_write;
-        tramp->opaque = opaque;
-
-        if (fd_read) {
-            cond |= G_IO_IN | G_IO_ERR;
-        }
+    tramp->fd_read = fd_read;
+    tramp->fd_write = fd_write;
+    tramp->opaque = opaque;
 
-        if (fd_write) {
-            cond |= G_IO_OUT | G_IO_ERR;
-        }
+    if (fd_read) {
+        cond |= G_IO_IN | G_IO_ERR;
+    }
 
-        tramp->chan = g_io_channel_unix_new(fd);
-        tramp->tag = g_io_add_watch(tramp->chan, cond, fd_trampoline, tramp);
+    if (fd_write) {
+        cond |= G_IO_OUT | G_IO_ERR;
     }
 
+    tramp->chan = g_io_channel_unix_new(fd);
+    tramp->tag = g_io_add_watch(tramp->chan, cond, fd_trampoline, tramp);
+
     return 0;
 }