Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Tuesday 29 June 2004 13:41, Lars Ellenberg wrote:
> On Tue, Jun 29, 2004 at 12:34:44AM +0200, Lars Ellenberg wrote:
> > as someone else already pointed out:
> > our definitions for the DEFINE_WAIT marco, as well as the
> > prepare_to_wait and _finish_wait functions, are the problem here.
> >
> >
> > DEFINE_WAIT is maped to DECLARE_WAIT, which initializes
> > w.task_list.{prev,next} == NULL, thus list_empty(&wait->task_list) is
> > false, and the wait thingy is never added to the list in
> > prepare_to_wait --- but it is removed later in finish_wait, where the
> > NULL dereference happens.
> >
> > in 2.6 this problem does not occur,
> > since there "list_empty_careful" is used...
> >
> >
> > anyways, this should help
> > (untested... I'm not at my own work place,
> > and currently I can not even do a test compile ...)
> >
> > lge
> >
> > Index: drbd_receiver.c
> > ===================================================================
> > RCS file: /var/lib/cvs/drbd/drbd/drbd/drbd_receiver.c,v
> > retrieving revision 1.97.2.175
> > diff -u -p -r1.97.2.175 drbd_receiver.c
> > --- drbd_receiver.c 26 Jun 2004 08:05:40 -0000 1.97.2.175
> > +++ drbd_receiver.c 28 Jun 2004 22:20:14 -0000
> > @@ -267,7 +267,10 @@ STATIC void finish_wait(wait_queue_head_
> > spin_unlock_irqrestore(&q->lock, flags);
> > }
> >
> > -#define DEFINE_WAIT(name) DECLARE_WAITQUEUE(name,current)
> > +#define DEFINE_WAIT(name) do { \
> > + DECLARE_WAITQUEUE(name,current);\
> > + list_init(&name.task_list); \
> > +} while (0)
> >
> > #endif
>
> nonsense, obviously the "DECLARE" would be valid only in the do {} block
> scope. it has been very late, this morning...
>
> correct patch will follow soonish...
>
I have committed this to CVS...
RCS file: /var/lib/cvs/drbd/drbd/drbd/drbd_receiver.c,v
retrieving revision 1.97.2.175
retrieving revision 1.97.2.176
diff -u -r1.97.2.175 -r1.97.2.176
--- drbd_receiver.c 26 Jun 2004 08:05:40 -0000 1.97.2.175
+++ drbd_receiver.c 30 Jun 2004 08:34:50 -0000 1.97.2.176
@@ -267,7 +267,13 @@
spin_unlock_irqrestore(&q->lock, flags);
}
-#define DEFINE_WAIT(name) DECLARE_WAITQUEUE(name,current)
+#define DEFINE_WAIT(name) \
+ wait_queue_t name = { \
+ .task = current, \
+ .task_list = { .next = &name.task_list, \
+ .prev = &name.task_list, \
+ }, \
+ }
#endif
-Philipp
--
: Dipl-Ing Philipp Reisner Tel +43-1-8178292-50 :
: LINBIT Information Technologies GmbH Fax +43-1-8178292-82 :
: Schönbrunnerstr 244, 1120 Vienna, Austria http://www.linbit.com :