[Qemu-devel] Re: [PATCH 3/3] savevm: Convert loadvm handlers list to LIST

[Luiz Capitulino <lcapitulino@redhat.com>]

On Tue, 01 Sep 2009 00:08:43 +0200
Juan Quintela <quintela@redhat.com> wrote:

> Luiz Capitulino <lcapitulino@redhat.com> wrote:
> > On Fri, 28 Aug 2009 22:31:57 +0200
> > Juan Quintela <quintela@redhat.com> wrote:
> >
> >> 
> >> Signed-off-by: Juan Quintela <quintela@redhat.com>
> >> ---
> >>  savevm.c |   20 +++++++++++---------
> >>  1 files changed, 11 insertions(+), 9 deletions(-)
> >> 
> >> diff --git a/savevm.c b/savevm.c
> >> index baef277..9836c60 100644
> >> --- a/savevm.c
> >> +++ b/savevm.c
> >> @@ -1260,10 +1260,10 @@ static SaveStateEntry *find_se(const char *idstr, int instance_id)
> >>  }
> >> 
> >>  typedef struct LoadStateEntry {
> >> +    LIST_ENTRY(LoadStateEntry) entry;
> >>      SaveStateEntry *se;
> >>      int section_id;
> >>      int version_id;
> >> -    struct LoadStateEntry *next;
> >>  } LoadStateEntry;
> >> 
> >>  static int qemu_loadvm_state_v2(QEMUFile *f)
> >> @@ -1309,7 +1309,8 @@ static int qemu_loadvm_state_v2(QEMUFile *f)
> >> 
> >>  int qemu_loadvm_state(QEMUFile *f)
> >>  {
> >> -    LoadStateEntry *first_le = NULL;
> >> +    LIST_HEAD(, LoadStateEntry) loadvm_handlers;
> >
> >  You're missing the initialization here, spot this while
> > testing staging.
> 
> I looked at aio.c and guess what :)  No LIST_INIT() either.

 As we talked by irc, if you are referring to 'aio_handlers' it's
global, so it will be initialized to 0 by the kernel.

> My understanding is that it is not needed (but it is better to add it,
> just in case the implementation change).

 I'm getting a segfault when I try to loadvm, I can write a recipe
to reproduce if needed.

> #define LIST_HEAD_INITIALIZER(head)                                     \
>         { NULL }
> 
> #define LIST_INIT(head) do {                                            \
>         (head)->lh_first = NULL;                                        \
> } while (/*CONSTCOND*/0)
> 
> 
> This should be what it does without puting it.  Perhaps we should
> "correct" also the other users?

 Yes, IMHO. Not because it's a fix, but it's good practice to use the API
w/o making assumptions on its internals.