* [PATCH v3 00/02] Consolidate tasklet + tasklet-hi code
@ 2018-02-27 16:48 Sebastian Andrzej Siewior
2018-02-27 16:48 ` [PATCH 1/2] kernel/sofirq: consolidate common code in __tasklet_schedule() + _hi_ Sebastian Andrzej Siewior
2018-02-27 16:48 ` [PATCH 2/2] kernel/sofirq: consolidate common code in tasklet_action() + tasklet_hi_action() Sebastian Andrzej Siewior
0 siblings, 2 replies; 5+ messages in thread
From: Sebastian Andrzej Siewior @ 2018-02-27 16:48 UTC (permalink / raw)
To: mingo; +Cc: linux-kernel, rostedt, tglx, Julia Cartwright
Ingo made a RT patch a few years back called "tasklet: Prevent tasklets
from going into infinite spin in RT" [0]. I ripped the non-RT pieces out
of it and here they are. I kept him as the original Author.
v1…v3: in v1 I had this_cpu_ptr(&tasklet_hi_vec) without disabling
interrupts and was objected by Steven. There are (indeed) some
users which use this outside if of the interrupt.
So in v2 I moved this but then Julia suggested pass just the
__percpu pointer and use this_cpu_ptr() once interrupts are
disabled.
This is all 1/2. 2/2 is unchanged because tasklet_action() /
tasklet_hi_action() run always in BH and can't migrate to another
CPU between this_cpu_() access and disabling interrupts.
[0] https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/tree/patches/tasklet-rt-prevent-tasklets-from-going-into-infinite-spin-in-rt.patch?h=linux-4.14.y-rt-patches
Sebastian
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 1/2] kernel/sofirq: consolidate common code in __tasklet_schedule() + _hi_
2018-02-27 16:48 [PATCH v3 00/02] Consolidate tasklet + tasklet-hi code Sebastian Andrzej Siewior
@ 2018-02-27 16:48 ` Sebastian Andrzej Siewior
2018-03-09 10:54 ` [tip:irq/core] softirq: Consolidate common code in __tasklet_[hi]_schedule() tip-bot for Ingo Molnar
2018-02-27 16:48 ` [PATCH 2/2] kernel/sofirq: consolidate common code in tasklet_action() + tasklet_hi_action() Sebastian Andrzej Siewior
1 sibling, 1 reply; 5+ messages in thread
From: Sebastian Andrzej Siewior @ 2018-02-27 16:48 UTC (permalink / raw)
To: mingo
Cc: linux-kernel, rostedt, tglx, Julia Cartwright, Ingo Molnar,
Sebastian Andrzej Siewior
From: Ingo Molnar <mingo@elte.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@elte.hu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bigeasy: splitted out from RT's "tasklet: Prevent tasklets from going
into infinite spin in RT" and added commit message. Do
this_cpu_ptr(headp) in __tasklet_schedule_common() as suggested by Julia
Cartwright]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/softirq.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 24d243ef8e71..2394b009994f 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -460,29 +460,33 @@ 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 __percpu *headp,
+ unsigned int softirq_nr)
{
+ struct tasklet_head *head;
unsigned long flags;
local_irq_save(flags);
+ head = this_cpu_ptr(headp);
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, &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, &tasklet_hi_vec,
+ HI_SOFTIRQ);
}
EXPORT_SYMBOL(__tasklet_hi_schedule);
--
2.16.2
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH 2/2] kernel/sofirq: consolidate common code in tasklet_action() + tasklet_hi_action()
2018-02-27 16:48 [PATCH v3 00/02] Consolidate tasklet + tasklet-hi code Sebastian Andrzej Siewior
2018-02-27 16:48 ` [PATCH 1/2] kernel/sofirq: consolidate common code in __tasklet_schedule() + _hi_ Sebastian Andrzej Siewior
@ 2018-02-27 16:48 ` Sebastian Andrzej Siewior
2018-03-09 10:55 ` [tip:irq/core] softirq: Consolidate common code in tasklet_[hi]_action() tip-bot for Ingo Molnar
1 sibling, 1 reply; 5+ messages in thread
From: Sebastian Andrzej Siewior @ 2018-02-27 16:48 UTC (permalink / raw)
To: mingo
Cc: linux-kernel, rostedt, tglx, Julia Cartwright, Ingo Molnar,
Sebastian Andrzej Siewior
From: Ingo Molnar <mingo@elte.hu>
tasklet_action() + tasklet_hi_action() 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@elte.hu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.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@linutronix.de>
---
kernel/softirq.c | 54 +++++++++++++++---------------------------------------
1 file changed, 15 insertions(+), 39 deletions(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 2394b009994f..177de3640c78 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -490,14 +490,16 @@ void __tasklet_hi_schedule(struct tasklet_struct *t)
}
EXPORT_SYMBOL(__tasklet_hi_schedule);
-static __latent_entropy void tasklet_action(struct softirq_action *a)
+static void tasklet_action_common(struct softirq_action *a,
+ struct tasklet_head *tl_head,
+ unsigned int softirq_nr)
{
struct tasklet_struct *list;
local_irq_disable();
- list = __this_cpu_read(tasklet_vec.head);
- __this_cpu_write(tasklet_vec.head, NULL);
- __this_cpu_write(tasklet_vec.tail, this_cpu_ptr(&tasklet_vec.head));
+ list = tl_head->head;
+ tl_head->head = NULL;
+ tl_head->tail = &tl_head->head;
local_irq_enable();
while (list) {
@@ -519,47 +521,21 @@ static __latent_entropy void tasklet_action(struct softirq_action *a)
local_irq_disable();
t->next = NULL;
- *__this_cpu_read(tasklet_vec.tail) = t;
- __this_cpu_write(tasklet_vec.tail, &(t->next));
- __raise_softirq_irqoff(TASKLET_SOFTIRQ);
+ *tl_head->tail = t;
+ tl_head->tail = &t->next;
+ __raise_softirq_irqoff(softirq_nr);
local_irq_enable();
}
}
+static __latent_entropy void tasklet_action(struct softirq_action *a)
+{
+ tasklet_action_common(a, this_cpu_ptr(&tasklet_vec), TASKLET_SOFTIRQ);
+}
+
static __latent_entropy void tasklet_hi_action(struct softirq_action *a)
{
- struct tasklet_struct *list;
-
- local_irq_disable();
- list = __this_cpu_read(tasklet_hi_vec.head);
- __this_cpu_write(tasklet_hi_vec.head, NULL);
- __this_cpu_write(tasklet_hi_vec.tail, this_cpu_ptr(&tasklet_hi_vec.head));
- local_irq_enable();
-
- while (list) {
- struct tasklet_struct *t = list;
-
- list = list->next;
-
- if (tasklet_trylock(t)) {
- if (!atomic_read(&t->count)) {
- if (!test_and_clear_bit(TASKLET_STATE_SCHED,
- &t->state))
- BUG();
- t->func(t->data);
- tasklet_unlock(t);
- continue;
- }
- tasklet_unlock(t);
- }
-
- local_irq_disable();
- 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_enable();
- }
+ tasklet_action_common(a, this_cpu_ptr(&tasklet_hi_vec), HI_SOFTIRQ);
}
void tasklet_init(struct tasklet_struct *t,
--
2.16.2
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [tip:irq/core] softirq: Consolidate common code in __tasklet_[hi]_schedule()
2018-02-27 16:48 ` [PATCH 1/2] kernel/sofirq: consolidate common code in __tasklet_schedule() + _hi_ Sebastian Andrzej Siewior
@ 2018-03-09 10:54 ` tip-bot for Ingo Molnar
0 siblings, 0 replies; 5+ messages in thread
From: tip-bot for Ingo Molnar @ 2018-03-09 10:54 UTC (permalink / raw)
To: linux-tip-commits
Cc: bigeasy, juliac, mingo, rostedt, hpa, tglx, linux-kernel
Commit-ID: 6498ddad301c7a94162915d06d1efe2e5d20f6dc
Gitweb: https://git.kernel.org/tip/6498ddad301c7a94162915d06d1efe2e5d20f6dc
Author: Ingo Molnar <mingo@kernel.org>
AuthorDate: Tue, 27 Feb 2018 17:48:07 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 9 Mar 2018 11:50:55 +0100
softirq: Consolidate common code in __tasklet_[hi]_schedule()
__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.
[ bigeasy: Splitted out from RT's "tasklet: Prevent tasklets from going
into infinite spin in RT" and added commit message. Use
this_cpu_ptr(headp) in __tasklet_schedule_common() as suggested
by Julia Cartwright ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Julia Cartwright <juliac@eso.teric.us>
Link: https://lkml.kernel.org/r/20180227164808.10093-2-bigeasy@linutronix.de
---
kernel/softirq.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 24d243ef8e71..2394b009994f 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -460,29 +460,33 @@ 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 __percpu *headp,
+ unsigned int softirq_nr)
{
+ struct tasklet_head *head;
unsigned long flags;
local_irq_save(flags);
+ head = this_cpu_ptr(headp);
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, &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, &tasklet_hi_vec,
+ HI_SOFTIRQ);
}
EXPORT_SYMBOL(__tasklet_hi_schedule);
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [tip:irq/core] softirq: Consolidate common code in tasklet_[hi]_action()
2018-02-27 16:48 ` [PATCH 2/2] kernel/sofirq: consolidate common code in tasklet_action() + tasklet_hi_action() Sebastian Andrzej Siewior
@ 2018-03-09 10:55 ` tip-bot for Ingo Molnar
0 siblings, 0 replies; 5+ messages in thread
From: tip-bot for Ingo Molnar @ 2018-03-09 10:55 UTC (permalink / raw)
To: linux-tip-commits
Cc: mingo, linux-kernel, juliac, hpa, bigeasy, tglx, rostedt
Commit-ID: 82b691bedf05f258f1c86c96ee574b0d7795c0a1
Gitweb: https://git.kernel.org/tip/82b691bedf05f258f1c86c96ee574b0d7795c0a1
Author: Ingo Molnar <mingo@kernel.org>
AuthorDate: Tue, 27 Feb 2018 17:48:08 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 9 Mar 2018 11:50:55 +0100
softirq: Consolidate common code in tasklet_[hi]_action()
tasklet_action() + tasklet_hi_action() are almost identical. Move the
common code from both function into __tasklet_action_common() and let
both functions invoke it with different arguments.
[ bigeasy: Splitted out from RT's "tasklet: Prevent tasklets from going
into infinite spin in RT" and added commit message]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Julia Cartwright <juliac@eso.teric.us>
Link: https://lkml.kernel.org/r/20180227164808.10093-3-bigeasy@linutronix.de
---
kernel/softirq.c | 54 +++++++++++++++---------------------------------------
1 file changed, 15 insertions(+), 39 deletions(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 2394b009994f..177de3640c78 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -490,14 +490,16 @@ void __tasklet_hi_schedule(struct tasklet_struct *t)
}
EXPORT_SYMBOL(__tasklet_hi_schedule);
-static __latent_entropy void tasklet_action(struct softirq_action *a)
+static void tasklet_action_common(struct softirq_action *a,
+ struct tasklet_head *tl_head,
+ unsigned int softirq_nr)
{
struct tasklet_struct *list;
local_irq_disable();
- list = __this_cpu_read(tasklet_vec.head);
- __this_cpu_write(tasklet_vec.head, NULL);
- __this_cpu_write(tasklet_vec.tail, this_cpu_ptr(&tasklet_vec.head));
+ list = tl_head->head;
+ tl_head->head = NULL;
+ tl_head->tail = &tl_head->head;
local_irq_enable();
while (list) {
@@ -519,47 +521,21 @@ static __latent_entropy void tasklet_action(struct softirq_action *a)
local_irq_disable();
t->next = NULL;
- *__this_cpu_read(tasklet_vec.tail) = t;
- __this_cpu_write(tasklet_vec.tail, &(t->next));
- __raise_softirq_irqoff(TASKLET_SOFTIRQ);
+ *tl_head->tail = t;
+ tl_head->tail = &t->next;
+ __raise_softirq_irqoff(softirq_nr);
local_irq_enable();
}
}
-static __latent_entropy void tasklet_hi_action(struct softirq_action *a)
+static __latent_entropy void tasklet_action(struct softirq_action *a)
{
- struct tasklet_struct *list;
-
- local_irq_disable();
- list = __this_cpu_read(tasklet_hi_vec.head);
- __this_cpu_write(tasklet_hi_vec.head, NULL);
- __this_cpu_write(tasklet_hi_vec.tail, this_cpu_ptr(&tasklet_hi_vec.head));
- local_irq_enable();
-
- while (list) {
- struct tasklet_struct *t = list;
-
- list = list->next;
-
- if (tasklet_trylock(t)) {
- if (!atomic_read(&t->count)) {
- if (!test_and_clear_bit(TASKLET_STATE_SCHED,
- &t->state))
- BUG();
- t->func(t->data);
- tasklet_unlock(t);
- continue;
- }
- tasklet_unlock(t);
- }
+ tasklet_action_common(a, this_cpu_ptr(&tasklet_vec), TASKLET_SOFTIRQ);
+}
- local_irq_disable();
- 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_enable();
- }
+static __latent_entropy void tasklet_hi_action(struct softirq_action *a)
+{
+ tasklet_action_common(a, this_cpu_ptr(&tasklet_hi_vec), HI_SOFTIRQ);
}
void tasklet_init(struct tasklet_struct *t,
^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-03-09 10:55 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2018-02-27 16:48 [PATCH v3 00/02] Consolidate tasklet + tasklet-hi code Sebastian Andrzej Siewior
2018-02-27 16:48 ` [PATCH 1/2] kernel/sofirq: consolidate common code in __tasklet_schedule() + _hi_ Sebastian Andrzej Siewior
2018-03-09 10:54 ` [tip:irq/core] softirq: Consolidate common code in __tasklet_[hi]_schedule() tip-bot for Ingo Molnar
2018-02-27 16:48 ` [PATCH 2/2] kernel/sofirq: consolidate common code in tasklet_action() + tasklet_hi_action() Sebastian Andrzej Siewior
2018-03-09 10:55 ` [tip:irq/core] softirq: Consolidate common code in tasklet_[hi]_action() tip-bot for Ingo Molnar
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