[PATCH 01/16] softirq: Make serving softirqs a task flag

Sebastian Andrzej Siewior
2013-02-13T16:11:56Z

From: Thomas Gleixner <tglx@linutronix.de>

Avoid the percpu softirq_runner pointer magic by using a task flag.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bigeasy@linutronix: different PF_IN_SOFTIRQ bit]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/sched.h | 1 +
kernel/softirq.c | 20 +++-----------------
2 files changed, 4 insertions(+), 17 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index e2f9e3b..751e65a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1821,6 +1821,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
/*
* Per process flags
*/
+#define PF_IN_SOFTIRQ 0x00000001 /* Task is serving softirq */
#define PF_STARTING 0x00000002 /* being created */
#define PF_EXITING 0x00000004 /* getting shut down */
#define PF_EXITPIDONE 0x00000008 /* pi exit done on shut down */
diff --git a/kernel/softirq.c b/kernel/softirq.c
index ca00a68..d4cace1 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -383,7 +383,6 @@ static inline void ksoftirqd_clr_sched_params(void) { }
* On RT we serialize softirq execution with a cpu local lock
*/
static DEFINE_LOCAL_IRQ_LOCK(local_softirq_lock);
-static DEFINE_PER_CPU(struct task_struct *, local_softirq_runner);

static void __do_softirq_common(int need_rcu_bh_qs);

@@ -438,22 +437,9 @@ void _local_bh_enable(void)
}
EXPORT_SYMBOL(_local_bh_enable);

-/* For tracing */
-int notrace __in_softirq(void)
-{
- if (__get_cpu_var(local_softirq_lock).owner == current)
- return __get_cpu_var(local_softirq_lock).nestcnt;
- return 0;
-}
-
int in_serving_softirq(void)
{
- int res;
-
- preempt_disable();
- res = __get_cpu_var(local_softirq_runner) == current;
- preempt_enable();
- return res;
+ return current->flags & PF_IN_SOFTIRQ;
}
EXPORT_SYMBOL(in_serving_softirq);

@@ -471,7 +457,7 @@ static void __do_softirq_common(int need_rcu_bh_qs)
/* Reset the pending bitmask before enabling irqs */
set_softirq_pending(0);

- __get_cpu_var(local_softirq_runner) = current;
+ current->flags |= PF_IN_SOFTIRQ;

lockdep_softirq_enter();

@@ -482,7 +468,7 @@ static void __do_softirq_common(int need_rcu_bh_qs)
wakeup_softirqd();

lockdep_softirq_exit();
- __get_cpu_var(local_softirq_runner) = NULL;
+ current->flags &= ~PF_IN_SOFTIRQ;

current->softirq_nestcnt--;
}
--
1.7.10.4