From: Ingo Molnar <mingo@elte.hu>
the patch below (ontop of rc2-mm2) fixes the fix. We must not do the
in_interrupt() check with softirqs still disabled because that will
always be true and we'll miss softirq processing ...
this patch fixes the following anomaly:
saturn:~/l> ./lat_tcp localhost
TCP latency using localhost: 1732.5386 microseconds
there was another(!) bug in the original patch as well:
preempt_count() -= SOFTIRQ_OFFSET - 1;
...
preempt_enable();
this is lethal on a !PREEMPT kernel, because preempt_enable() is a NOP
there ...
Ingo
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/kernel/softirq.c | 21 ++++++++++-----------
1 files changed, 10 insertions(+), 11 deletions(-)
diff -puN kernel/softirq.c~softirqs-fix-latency-of-softirq-processing-fix kernel/softirq.c
--- 25/kernel/softirq.c~softirqs-fix-latency-of-softirq-processing-fix Thu Sep 23 14:37:36 2004
+++ 25-akpm/kernel/softirq.c Thu Sep 23 14:37:36 2004
@@ -138,18 +138,17 @@ EXPORT_SYMBOL(do_softirq);
void local_bh_enable(void)
{
WARN_ON(irqs_disabled());
- if (unlikely(!in_interrupt() && local_softirq_pending())) {
- /*
- * Keep preemption disabled until we are done with
- * softirq processing:
- */
- preempt_count() -= SOFTIRQ_OFFSET - 1;
+ /*
+ * Keep preemption disabled until we are done with
+ * softirq processing:
+ */
+ preempt_count() -= SOFTIRQ_OFFSET - 1;
+
+ if (unlikely(!in_interrupt() && local_softirq_pending()))
invoke_softirq();
- preempt_enable();
- } else {
- __local_bh_enable();
- preempt_check_resched();
- }
+
+ dec_preempt_count();
+ preempt_check_resched();
}
EXPORT_SYMBOL(local_bh_enable);
_