linux-kernel - [PATCH 1/2] kernel/sofirq: consolidate common code in __tasklet_schedule() + _hi

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Message-Id: <20180215172042.31573-2-bigeasy@linutronix.de>
Date:   Thu, 15 Feb 2018 18:20:41 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     mingo@...nel.org
Cc:     linux-kernel@...r.kernel.org, rostedt@...dmis.org,
        tglx@...utronix.de, Ingo Molnar <mingo@...e.hu>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 1/2] kernel/sofirq: consolidate common code in __tasklet_schedule() + _hi_

From: Ingo Molnar <mingo@...e.hu>

__tasklet_schedule() and __tasklet_hi_schedule() are almost identical.
Move the common code from both function into __tasklet_schedule_common()
and let both functions invoke it with different arguments.

Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
[bigeasy: splitted out from RT's "tasklet: Prevent tasklets from going
into infinite spin in RT" and added commit message]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/softirq.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 24d243ef8e71..145cf6a2e7c9 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -460,29 +460,31 @@ struct tasklet_head {
 static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec);
 static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec);
 
-void __tasklet_schedule(struct tasklet_struct *t)
+static void __tasklet_schedule_common(struct tasklet_struct *t,
+				      struct tasklet_head *head,
+				      unsigned int softirq_nr)
 {
 	unsigned long flags;
 
 	local_irq_save(flags);
 	t->next = NULL;
-	*__this_cpu_read(tasklet_vec.tail) = t;
-	__this_cpu_write(tasklet_vec.tail, &(t->next));
-	raise_softirq_irqoff(TASKLET_SOFTIRQ);
+	*head->tail = t;
+	head->tail = &(t->next);
+	raise_softirq_irqoff(softirq_nr);
 	local_irq_restore(flags);
 }
+
+void __tasklet_schedule(struct tasklet_struct *t)
+{
+	__tasklet_schedule_common(t, this_cpu_ptr(&tasklet_vec),
+				  TASKLET_SOFTIRQ);
+}
 EXPORT_SYMBOL(__tasklet_schedule);
 
 void __tasklet_hi_schedule(struct tasklet_struct *t)
 {
-	unsigned long flags;
-
-	local_irq_save(flags);
-	t->next = NULL;
-	*__this_cpu_read(tasklet_hi_vec.tail) = t;
-	__this_cpu_write(tasklet_hi_vec.tail,  &(t->next));
-	raise_softirq_irqoff(HI_SOFTIRQ);
-	local_irq_restore(flags);
+	__tasklet_schedule_common(t, this_cpu_ptr(&tasklet_hi_vec),
+				  HI_SOFTIRQ);
 }
 EXPORT_SYMBOL(__tasklet_hi_schedule);
 
-- 
2.16.1