On 19/06/07, Jan Kiszka <[EMAIL PROTECTED]> wrote:
> > [ ... ]
> >
> > --- ksrc/nucleus/intr.c-orig 2007-06-19 13:44:55.090623404 +0200
> > +++ ksrc/nucleus/intr.c 2007-06-19 14:38:36.073535255 +0200
> > @@ -259,7 +259,7 @@ static void xnintr_edge_shirq_handler(un
> > xnstat_runtime_t *prev;
> > xnticks_t start;
> > xnintr_shirq_t *shirq = &xnshirqs[irq];
> > - xnintr_t *intr, *end = NULL;
> > + xnintr_t *intr, *end = NULL, *old_end = NULL;
> > int s = 0, counter = 0;
> >
> > xnarch_memory_barrier();
> > @@ -273,7 +273,7 @@ static void xnintr_edge_shirq_handler(un
> > xnintr_shirq_lock(shirq);
> > intr = shirq->handlers;
> >
> > - while (intr != end) {
> > + while (intr && intr != end) {
> > int ret, code;
> >
> > xnstat_runtime_switch(sched,
> > @@ -297,8 +297,14 @@ static void xnintr_edge_shirq_handler(un
> > if (counter++ > MAX_EDGEIRQ_COUNTER)
> > break;
> >
> > - if (!(intr = intr->next))
> > + if (!(intr = intr->next)) {
> > intr = shirq->handlers;
> > +
> > + /* 'end' has been removed in the mean time. */
> > + if (end && old_end == end)
> > + intr = NULL;
> > + old_end = end;
> > + }
>
> "end" may still remain stuck on an xnintr object that was removed.
> Unless some other element becomes "end" while continuing with the chain,
> I don't see a way out of this loop.
But that's why 'old_end == end'.. i.e. if we finished iteration over
all the handlers and on the current iteration N 'end' is the same as
it was on iteration N-1 .. --- 'end' has been (probably) removed..
although, 'old_end' should be cleared when 'end' changes.. hum?
IOW, it catches a moment when the full iteration took place and 'end'
is the same as it was on iteration N-1.. moreover, 'end' has _not_
changed during iteration N.
at the same time,
...
while (intr && intr != end) {
...
did't took place so 'end' is invalid.. we set 'intr = NULL' and the loop ends.
I'll take a closer look later but I think it should work. Although,
maybe I just can't sanely estimate whole ugliness of this fix at the
moment :-)
-
--- ksrc/nucleus/intr.c-orig 2007-06-19 13:44:55.090623404 +0200
+++ ksrc/nucleus/intr.c 2007-06-19 15:17:55.787849783 +0200
@@ -259,7 +259,7 @@ static void xnintr_edge_shirq_handler(un
xnstat_runtime_t *prev;
xnticks_t start;
xnintr_shirq_t *shirq = &xnshirqs[irq];
- xnintr_t *intr, *end = NULL;
+ xnintr_t *intr, *end = NULL, *old_end = NULL;
int s = 0, counter = 0;
xnarch_memory_barrier();
@@ -273,7 +273,7 @@ static void xnintr_edge_shirq_handler(un
xnintr_shirq_lock(shirq);
intr = shirq->handlers;
- while (intr != end) {
+ while (intr && intr != end) {
int ret, code;
xnstat_runtime_switch(sched,
@@ -291,14 +291,22 @@ static void xnintr_edge_shirq_handler(un
&intr->stat[xnsched_cpu(sched)].account,
start);
start = xnstat_runtime_now();
- } else if (code == XN_ISR_NONE && end == NULL)
+ } else if (code == XN_ISR_NONE && end == NULL) {
end = intr;
+ old_end = NULL;
+ }
if (counter++ > MAX_EDGEIRQ_COUNTER)
break;
- if (!(intr = intr->next))
+ if (!(intr = intr->next)) {
intr = shirq->handlers;
+
+ /* 'end' has been removed in the mean time. */
+ if (end && old_end == end)
+ intr = NULL;
+ old_end = end;
+ }
}
xnintr_shirq_unlock(shirq);
--
Best regards,
Dmitry Adamushko
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