[PATCH 1/2 v2] kernel/sofirq: consolidate common code in __tasklet_schedule() + _hi_

From: Sebastian Andrzej Siewior
Date: Fri Feb 16 2018 - 12:08:49 EST


From: Ingo Molnar <mingo@xxxxxxx>

__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@xxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
[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@xxxxxxxxxxxxx>
---
v1âv2: use local_irq_save() within the non-common.

kernel/softirq.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 24d243ef8e71..860679e357e2 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -460,15 +460,24 @@ struct tasklet_head {
static DEFINE_PER_CPU(struct tasklet_head, tasklet_vec);
static DEFINE_PER_CPU(struct tasklet_head, tasklet_hi_vec);

+static void __tasklet_schedule_common(struct tasklet_struct *t,
+ struct tasklet_head *head,
+ unsigned int softirq_nr)
+{
+
+ t->next = NULL;
+ *head->tail = t;
+ head->tail = &(t->next);
+ raise_softirq_irqoff(softirq_nr);
+}
+
void __tasklet_schedule(struct tasklet_struct *t)
{
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);
+ __tasklet_schedule_common(t, this_cpu_ptr(&tasklet_vec),
+ TASKLET_SOFTIRQ);
local_irq_restore(flags);
}
EXPORT_SYMBOL(__tasklet_schedule);
@@ -478,10 +487,8 @@ 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);
+ __tasklet_schedule_common(t, this_cpu_ptr(&tasklet_hi_vec),
+ HI_SOFTIRQ);
local_irq_restore(flags);
}
EXPORT_SYMBOL(__tasklet_hi_schedule);
--
2.16.1