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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
Carsten Emde <C.Emde@osadl.org>, Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH 01/16] softirq: Make serving softirqs a task flag
Date: Wed, 13 Feb 2013 17:11:56 +0100
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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(-)
Index: linux-3.2.39-rt59/include/linux/sched.h
===================================================================
@ linux-3.2.39-rt59/include/linux/sched.h:1835 @ extern void thread_group_times(struct ta
/*
* 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 */
Index: linux-3.2.39-rt59/kernel/softirq.c
===================================================================
--- linux-3.2.39-rt59.orig/kernel/softirq.c
+++ linux-3.2.39-rt59/kernel/softirq.c
@ linux-3.2.39-rt59/include/linux/sched.h:386 @ static inline void ksoftirqd_clr_sched_p
* 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);
@ linux-3.2.39-rt59/include/linux/sched.h:440 @ 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);
@ linux-3.2.39-rt59/include/linux/sched.h:460 @ static void __do_softirq_common(int need
/* 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();
@ linux-3.2.39-rt59/include/linux/sched.h:471 @ static void __do_softirq_common(int need
wakeup_softirqd();
lockdep_softirq_exit();
- __get_cpu_var(local_softirq_runner) = NULL;
+ current->flags &= ~PF_IN_SOFTIRQ;
current->softirq_nestcnt--;
}