2007-10-10 12:16:32

by Johannes Weiner

Subject: [PATCH] __do_softirq() loop cleanup

Hi,

This changes __do_softirq() to use a C looping construct instead of
simulating one by means of goto.

Signed-off-by: Johannes Weiner <[email protected]>

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 0f546dd..bacee6b 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -212,38 +212,37 @@ asmlinkage void __do_softirq(void)
int max_restart = MAX_SOFTIRQ_RESTART;
int cpu;

- pending = local_softirq_pending();
account_system_vtime(current);

__local_bh_disable((unsigned long)__builtin_return_address(0));
trace_softirq_enter();

cpu = smp_processor_id();
-restart:
- /* Reset the pending bitmask before enabling irqs */
- set_softirq_pending(0);

- local_irq_enable();
+ while ((pending = local_softirq_pending())) {
+ if (!max_restart--) {
+ wakeup_softirqd();
+ break;
+ }

- h = softirq_vec;
+ /* Reset the pending bitmask before enabling irqs */
+ set_softirq_pending(0);

- do {
- if (pending & 1) {
- h->action(h);
- rcu_bh_qsctr_inc(cpu);
- }
- h++;
- pending >>= 1;
- } while (pending);
+ local_irq_enable();

- local_irq_disable();
+ h = softirq_vec;

- pending = local_softirq_pending();
- if (pending && --max_restart)
- goto restart;
+ do {
+ if (pending & 1) {
+ h->action(h);
+ rcu_bh_qsctr_inc(cpu);
+ }
+ h++;
+ pending >>= 1;
+ } while (pending);

- if (pending)
- wakeup_softirqd();
+ local_irq_disable();
+ }

trace_softirq_exit();

2007-10-12 02:26:43

by Steven Rostedt

Subject: Re: [PATCH] __do_softirq() loop cleanup

On Wed, Oct 10, 2007 at 02:16:19PM +0200, Johannes Weiner wrote:
> Hi,
>
> This changes __do_softirq() to use a C looping construct instead of
> simulating one by means of goto.
>
> Signed-off-by: Johannes Weiner <[email protected]>
>

I've read over the logic three times and it seems to keep with the
original design. So unless I missed something ...

Acked-by: Steven Rostedt <[email protected]>

-- Steve