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Subject[PATCH 1/2] softirq: introduce loacal_bh_enable_force_wake()
On Thu, Feb 03, 2011 at 06:17:39PM +0800, Yong Zhang wrote:
> Maybe we can introduce another type of local_bh_enable() in which
> waking up ksoftirqd is forced if needed.

---
From: Yong Zhang <yong.zhang0@gmail.com>
Subject: [PATCH 1/2] softirq: introduce loacal_bh_enable_force_wake()
If there is pending softirq, don't handle it in the caller's
context, invoke ksoftirqd directly instead.

del_timer_sync() will be the first caller.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/bottom_half.h | 1 +
kernel/softirq.c | 19 ++++++++++++++-----
2 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/include/linux/bottom_half.h b/include/linux/bottom_half.h
index 27b1bcf..665d697 100644
--- a/include/linux/bottom_half.h
+++ b/include/linux/bottom_half.h
@@ -5,5 +5,6 @@ extern void local_bh_disable(void);
extern void _local_bh_enable(void);
extern void local_bh_enable(void);
extern void local_bh_enable_ip(unsigned long ip);
+extern void local_bh_enable_force_wake(void);

#endif /* _LINUX_BH_H */
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 68eb5ef..5f224d4 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -154,7 +154,7 @@ void _local_bh_enable(void)

EXPORT_SYMBOL(_local_bh_enable);

-static inline void _local_bh_enable_ip(unsigned long ip)
+static inline void _local_bh_enable_ip(unsigned long ip, bool force_wake)
{
WARN_ON_ONCE(in_irq() || irqs_disabled());
#ifdef CONFIG_TRACE_IRQFLAGS
@@ -171,8 +171,12 @@ static inline void _local_bh_enable_ip(unsigned long ip)
*/
sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1);

- if (unlikely(!in_interrupt() && local_softirq_pending()))
- do_softirq();
+ if (unlikely(!in_interrupt() && local_softirq_pending())) {
+ if (!force_wake)
+ do_softirq();
+ else
+ wakeup_softirqd();
+ }

dec_preempt_count();
#ifdef CONFIG_TRACE_IRQFLAGS
@@ -183,16 +187,21 @@ static inline void _local_bh_enable_ip(unsigned long ip)

void local_bh_enable(void)
{
- _local_bh_enable_ip((unsigned long)__builtin_return_address(0));
+ _local_bh_enable_ip((unsigned long)__builtin_return_address(0), false);
}
EXPORT_SYMBOL(local_bh_enable);

void local_bh_enable_ip(unsigned long ip)
{
- _local_bh_enable_ip(ip);
+ _local_bh_enable_ip(ip, false);
}
EXPORT_SYMBOL(local_bh_enable_ip);

+void local_bh_enable_force_wake(void)
+{
+ _local_bh_enable_ip((unsigned long)__builtin_return_address(0), true);
+}
+EXPORT_SYMBOL(local_bh_enable_force_wake);
/*
* We restart softirq processing MAX_SOFTIRQ_RESTART times,
* and we fall back to softirqd after that.
--
1.7.1


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