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Subject: softirq: Make serving softirqs a task flag
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 04 Oct 2012 14:30:25 +0100
Avoid the percpu softirq_runner pointer magic by using a task flag.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/sched.h | 1 +
kernel/softirq.c | 20 +++-----------------
2 files changed, 4 insertions(+), 17 deletions(-)
Index: linux-stable/include/linux/sched.h
===================================================================
--- linux-stable.orig/include/linux/sched.h
+++ linux-stable/include/linux/sched.h
@@ -1845,6 +1845,7 @@ extern void thread_group_times(struct ta
#define PF_MEMALLOC 0x00000800 /* Allocating memory */
#define PF_NPROC_EXCEEDED 0x00001000 /* set_user noticed that RLIMIT_NPROC was exceeded */
#define PF_USED_MATH 0x00002000 /* if unset the fpu must be initialized before use */
+#define PF_IN_SOFTIRQ 0x00004000 /* Task is serving softirq */
#define PF_NOFREEZE 0x00008000 /* this thread should not be frozen */
#define PF_FROZEN 0x00010000 /* frozen for system suspend */
#define PF_FSTRANS 0x00020000 /* inside a filesystem transaction */
Index: linux-stable/kernel/softirq.c
===================================================================
--- linux-stable.orig/kernel/softirq.c
+++ linux-stable/kernel/softirq.c
@@ -392,7 +392,6 @@ 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);
@@ -447,22 +446,9 @@ 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);
@@ -480,7 +466,7 @@ 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();
@@ -491,7 +477,7 @@ 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--;
}
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