Re: [Xen-devel] xenstore xenbus failure

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2009-01-20 at 11:12 -0800, Adam Wendt wrote:
> Hi,
> 
> Still having problems getting xenstore working without the socket
> interface. Here is output running simple xenstore-ls:
> 
> Got message DIRECTORY len 2 from 0x1451b80
> Writing msg DIRECTORY (tool) out to 0x1451b80
> xenstore-ls: xs_directory (/): Invalid argument
> IN 0x1451b80 20090120 10:43:23 DIRECTORY (/ )
> OUT 0x1451b80 20090120 10:43:23 DIRECTORY (tool vm local )

I just noticed something very similar...
        root@bogga:~# xenstore-ls 
        xenstore-ls: xs_directory (/): Success
        root@bogga:~# strace xenstore-ls
        [...]
        open("/proc/xen/xenbus", O_RDWR|O_LARGEFILE) = 3
        [...]
        write(3, "\1\0\0\0\0\0\0\0\0\0\0\0\2\0\0\0", 16) = 16
        write(3, "/\0", 2)                      = -168004416

I don't like the look of that return value and:
          CC      drivers/xen/xenfs/xenbus.o
        /local/scratch/ianc/devel/kernels/paravirt/drivers/xen/xenfs/xenbus.c: 
In function 'xenbus_file_write':
        
/local/scratch/ianc/devel/kernels/paravirt/drivers/xen/xenfs/xenbus.c:294: 
warning: 'rc' may be used uninitialized in this function

Can you try this patch, it fixes things for me:

diff -r 8fed53a1d8d1 drivers/xen/xenfs/xenbus.c
--- a/drivers/xen/xenfs/xenbus.c        Fri Jan 23 14:16:11 2009 +0000
+++ b/drivers/xen/xenfs/xenbus.c        Fri Jan 23 15:21:12 2009 +0000
@@ -291,7 +291,7 @@
 static int xenbus_write_transaction(unsigned msg_type,
                                    struct xenbus_file_priv *u)
 {
-       int rc, ret;
+       int rc;
        void *reply;
        struct xenbus_transaction_holder *trans = NULL;
        LIST_HEAD(staging_q);
@@ -326,15 +326,14 @@
        }
 
        mutex_lock(&u->reply_mutex);
-       ret = queue_reply(&staging_q, &u->u.msg, sizeof(u->u.msg));
-       if (!ret)
-               ret = queue_reply(&staging_q, reply, u->u.msg.len);
-       if (!ret) {
+       rc = queue_reply(&staging_q, &u->u.msg, sizeof(u->u.msg));
+       if (!rc)
+               rc = queue_reply(&staging_q, reply, u->u.msg.len);
+       if (!rc) {
                list_splice_tail(&staging_q, &u->read_buffers);
                wake_up(&u->read_waitq);
        } else {
                queue_cleanup(&staging_q);
-               rc = ret;
        }
        mutex_unlock(&u->reply_mutex);
 


Ian.



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