Re: [Qemu-devel] [PATCH 2/5] runstate: Print state transition when invalid

[Luiz Capitulino <lcapitulino@redhat.com>]

On Wed, 19 Oct 2011 08:43:33 +0800
Wen Congyang <wency@cn.fujitsu.com> wrote:

> At 10/15/2011 01:26 AM, Luiz Capitulino Write:
> > Makes it easier to debug.
> > 
> > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> > ---
> >  vl.c |    4 +++-
> >  1 files changed, 3 insertions(+), 1 deletions(-)
> > 
> > diff --git a/vl.c b/vl.c
> > index dbf7778..6645720 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -397,7 +397,9 @@ void runstate_set(RunState new_state)
> >  {
> >      if (new_state >= RUN_STATE_MAX ||
> >          !runstate_valid_transitions[current_run_state][new_state]) {
> > -        fprintf(stderr, "invalid runstate transition\n");
> > +        fprintf(stderr, "ERROR: invalid runstate transition: '%s' -> '%s'\n",
> > +                RunState_lookup[current_run_state],
> > +                RunState_lookup[new_state]);
> 
> If new_state >= RUN_STATE_MAX, we can not use RunState_lookup.

Good catch!

> I think it's better to use:
>     new_state >= RUN_STATE_MAX ? "invalid state" : RunState_lookup[new_state]

I prefer to do the following instead:

diff --git a/vl.c b/vl.c
index 2dce3ae..2a634a7 100644
--- a/vl.c
+++ b/vl.c
@@ -393,9 +393,12 @@ void runstate_init(void)
 /* This function will abort() on invalid state transitions */
 void runstate_set(RunState new_state)
 {
-    if (new_state >= RUN_STATE_MAX ||
-        !runstate_valid_transitions[current_run_state][new_state]) {
-        fprintf(stderr, "invalid runstate transition\n");
+    assert(new_state < RUN_STATE_MAX);
+
+    if (!runstate_valid_transitions[current_run_state][new_state]) {
+        fprintf(stderr, "ERROR: invalid runstate transition: '%s' -> '%s'\n",
+                RunState_lookup[current_run_state],
+                RunState_lookup[new_state]);
         abort();
     }
 
-- 
1.7.7.rc3


> 
> Thanks
> Wen Congyang
> 
> >          abort();
> >      }
> >  
>