[patch 0/3] net: Sanitizing hrtimer usage in net/sched/sch_cbq.c

[Peter Zijlstra-5]

Thomas, will you take this?

---
Subject: softirq: tasklet_hrtimer
From: Peter Zijlstra <a.p.zijlstra@...>
Date: Wed Jul 22 14:18:35 CEST 2009

Stick tasklets and hrtimers together to provide an in-softirq hrtimer
experience.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...>
---
 include/linux/interrupt.h |   11 +++++++++++
 kernel/softirq.c          |   44 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 54 insertions(+), 1 deletion(-)

Index: linux-2.6/include/linux/interrupt.h
===================================================================
--- linux-2.6.orig/include/linux/interrupt.h
+++ linux-2.6/include/linux/interrupt.h
@@ -14,6 +14,7 @@
 #include <linux/irqflags.h>
 #include <linux/smp.h>
 #include <linux/percpu.h>
+#include <linux/hrtimer.h>
 
 #include <asm/atomic.h>
 #include <asm/ptrace.h>
@@ -517,6 +518,16 @@ extern void tasklet_kill_immediate(struc
 extern void tasklet_init(struct tasklet_struct *t,
  void (*func)(unsigned long), unsigned long data);
 
+struct tasklet_hrtimer {
+ struct hrtimer timer;
+ struct tasklet_struct tasklet;
+ enum hrtimer_restart (*function)(struct hrtimer *);
+};
+
+void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
+  enum hrtimer_restart (*function)(struct hrtimer *),
+  clockid_t which_clock, enum hrtimer_mode mode);
+
 /*
  * Autoprobing for irqs:
  *
Index: linux-2.6/kernel/softirq.c
===================================================================
--- linux-2.6.orig/kernel/softirq.c
+++ linux-2.6/kernel/softirq.c
@@ -345,7 +345,9 @@ void open_softirq(int nr, void (*action)
  softirq_vec[nr].action = action;
 }
 
-/* Tasklets */
+/*
+ * Tasklets
+ */
 struct tasklet_head
 {
  struct tasklet_struct *head;
@@ -493,6 +495,46 @@ void tasklet_kill(struct tasklet_struct
 
 EXPORT_SYMBOL(tasklet_kill);
 
+/*
+ * tasklet_hrtimer
+ */
+
+static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer)
+{
+ struct tasklet_hrtimer *ttimer =
+ container_of(timer, struct tasklet_hrtimer, timer);
+
+ tasklet_hi_schedule(&ttimer->tasklet);
+
+ return HRTIMER_NORESTART;
+}
+
+static void __tasklet_hrtimer_trampoline(unsigned long data)
+{
+ struct tasklet_hrtimer *ttimer = (void *)data;
+ enum hrtimer_restart restart;
+
+ restart = ttimer->function(&ttimer->timer);
+ if (restart != HRTIMER_NORESTART)
+ hrtimer_restart(&ttimer->timer);
+}
+
+void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
+  enum hrtimer_restart (*function)(struct hrtimer *),
+  clockid_t which_clock, enum hrtimer_mode mode)
+{
+ hrtimer_init(&ttimer->timer, which_clock, mode);
+ ttimer->timer.function = __hrtimer_tasklet_trampoline;
+ tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline,
+     (unsigned long)ttimer);
+ ttimer->function = function;
+}
+EXPORT_SYMBOL_GPL(tasklet_hrtimer_init);
+
+/*
+ * Remote softirq bits
+ */
+
 DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list);
 EXPORT_PER_CPU_SYMBOL(softirq_work_list);
 

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[Peter Zijlstra-5]

Commit-ID:  d34dc684eaad4e9561bbce423ac2581a48441fb0
Gitweb:     http://git.kernel.org/tip/d34dc684eaad4e9561bbce423ac2581a48441fb0
Author:     Peter Zijlstra <peterz@...>
AuthorDate: Wed, 22 Jul 2009 14:18:35 +0200
Committer:  Thomas Gleixner <tglx@...>
CommitDate: Wed, 22 Jul 2009 15:53:28 +0200

softirq: introduce tasklet_hrtimer infrastructure

commit ca109491f (hrtimer: removing all ur callback modes) moved all
hrtimer callbacks into hard interrupt context when high resolution
timers are active. That breaks code which relied on the assumption
that the callback happens in softirq context.

Provide a generic infrastructure which combines tasklets and hrtimers
together to provide an in-softirq hrtimer experience.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...>
Cc: torvalds@...
Cc: kaber@...
Cc: David Miller <davem@...>
LKML-Reference: <1248265724.27058.1366.camel@twins>
Signed-off-by: Thomas Gleixner <tglx@...>


---
 include/linux/interrupt.h |   26 ++++++++++++++++++
 kernel/softirq.c          |   64 ++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 89 insertions(+), 1 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 2721f07..fd4c9c6 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -14,6 +14,7 @@
 #include <linux/irqflags.h>
 #include <linux/smp.h>
 #include <linux/percpu.h>
+#include <linux/hrtimer.h>
 
 #include <asm/atomic.h>
 #include <asm/ptrace.h>
@@ -517,6 +518,31 @@ extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu);
 extern void tasklet_init(struct tasklet_struct *t,
  void (*func)(unsigned long), unsigned long data);
 
+struct tasklet_hrtimer {
+ struct hrtimer timer;
+ struct tasklet_struct tasklet;
+ enum hrtimer_restart (*function)(struct hrtimer *);
+};
+
+extern void
+tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
+     enum hrtimer_restart (*function)(struct hrtimer *),
+     clockid_t which_clock, enum hrtimer_mode mode);
+
+static inline
+int tasklet_hrtimer_start(struct tasklet_hrtimer *ttimer, ktime_t time,
+  const enum hrtimer_mode mode)
+{
+ return hrtimer_start(&ttimer->timer, time, mode);
+}
+
+static inline
+void tasklet_hrtimer_cancel(struct tasklet_hrtimer *ttimer)
+{
+ hrtimer_cancel(&ttimer->timer);
+ tasklet_kill(&ttimer->tasklet);
+}
+
 /*
  * Autoprobing for irqs:
  *
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 3a94905..eb5e131 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -345,7 +345,9 @@ void open_softirq(int nr, void (*action)(struct softirq_action *))
  softirq_vec[nr].action = action;
 }
 
-/* Tasklets */
+/*
+ * Tasklets
+ */
 struct tasklet_head
 {
  struct tasklet_struct *head;
@@ -493,6 +495,66 @@ void tasklet_kill(struct tasklet_struct *t)
 
 EXPORT_SYMBOL(tasklet_kill);
 
+/*
+ * tasklet_hrtimer
+ */
+
+/*
+ * The trampoline is called when the hrtimer expires. If this is
+ * called from the hrtimer interrupt then we schedule the tasklet as
+ * the timer callback function expects to run in softirq context. If
+ * it's called in softirq context anyway (i.e. high resolution timers
+ * disabled) then the hrtimer callback is called right away.
+ */
+static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer)
+{
+ struct tasklet_hrtimer *ttimer =
+ container_of(timer, struct tasklet_hrtimer, timer);
+
+ if (hrtimer_is_hres_active(timer)) {
+ tasklet_hi_schedule(&ttimer->tasklet);
+ return HRTIMER_NORESTART;
+ }
+ return ttimer->function(timer);
+}
+
+/*
+ * Helper function which calls the hrtimer callback from
+ * tasklet/softirq context
+ */
+static void __tasklet_hrtimer_trampoline(unsigned long data)
+{
+ struct tasklet_hrtimer *ttimer = (void *)data;
+ enum hrtimer_restart restart;
+
+ restart = ttimer->function(&ttimer->timer);
+ if (restart != HRTIMER_NORESTART)
+ hrtimer_restart(&ttimer->timer);
+}
+
+/**
+ * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks
+ * @ttimer: tasklet_hrtimer which is initialized
+ * @function: hrtimer callback funtion which gets called from softirq context
+ * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME)
+ * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL)
+ */
+void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
+  enum hrtimer_restart (*function)(struct hrtimer *),
+  clockid_t which_clock, enum hrtimer_mode mode)
+{
+ hrtimer_init(&ttimer->timer, which_clock, mode);
+ ttimer->timer.function = __hrtimer_tasklet_trampoline;
+ tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline,
+     (unsigned long)ttimer);
+ ttimer->function = function;
+}
+EXPORT_SYMBOL_GPL(tasklet_hrtimer_init);
+
+/*
+ * Remote softirq bits
+ */
+
 DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list);
 EXPORT_PER_CPU_SYMBOL(softirq_work_list);
 
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[Peter Zijlstra-5]

Commit-ID:  9ba5f005c994ad28e266a0cd14ef29354be382c9
Gitweb:     http://git.kernel.org/tip/9ba5f005c994ad28e266a0cd14ef29354be382c9
Author:     Peter Zijlstra <peterz@...>
AuthorDate: Wed, 22 Jul 2009 14:18:35 +0200
Committer:  Thomas Gleixner <tglx@...>
CommitDate: Wed, 22 Jul 2009 17:01:17 +0200

softirq: introduce tasklet_hrtimer infrastructure

commit ca109491f (hrtimer: removing all ur callback modes) moved all
hrtimer callbacks into hard interrupt context when high resolution
timers are active. That breaks code which relied on the assumption
that the callback happens in softirq context.

Provide a generic infrastructure which combines tasklets and hrtimers
together to provide an in-softirq hrtimer experience.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...>
Cc: torvalds@...
Cc: kaber@...
Cc: David Miller <davem@...>
LKML-Reference: <1248265724.27058.1366.camel@twins>
Signed-off-by: Thomas Gleixner <tglx@...>


---
 include/linux/interrupt.h |   26 ++++++++++++++++++
 kernel/softirq.c          |   64 ++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 89 insertions(+), 1 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 2721f07..fd4c9c6 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -14,6 +14,7 @@
 #include <linux/irqflags.h>
 #include <linux/smp.h>
 #include <linux/percpu.h>
+#include <linux/hrtimer.h>
 
 #include <asm/atomic.h>
 #include <asm/ptrace.h>
@@ -517,6 +518,31 @@ extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu);
 extern void tasklet_init(struct tasklet_struct *t,
  void (*func)(unsigned long), unsigned long data);
 
+struct tasklet_hrtimer {
+ struct hrtimer timer;
+ struct tasklet_struct tasklet;
+ enum hrtimer_restart (*function)(struct hrtimer *);
+};
+
+extern void
+tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
+     enum hrtimer_restart (*function)(struct hrtimer *),
+     clockid_t which_clock, enum hrtimer_mode mode);
+
+static inline
+int tasklet_hrtimer_start(struct tasklet_hrtimer *ttimer, ktime_t time,
+  const enum hrtimer_mode mode)
+{
+ return hrtimer_start(&ttimer->timer, time, mode);
+}
+
+static inline
+void tasklet_hrtimer_cancel(struct tasklet_hrtimer *ttimer)
+{
+ hrtimer_cancel(&ttimer->timer);
+ tasklet_kill(&ttimer->tasklet);
+}
+
 /*
  * Autoprobing for irqs:
  *
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 3a94905..eb5e131 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -345,7 +345,9 @@ void open_softirq(int nr, void (*action)(struct softirq_action *))
  softirq_vec[nr].action = action;
 }
 
-/* Tasklets */
+/*
+ * Tasklets
+ */
 struct tasklet_head
 {
  struct tasklet_struct *head;
@@ -493,6 +495,66 @@ void tasklet_kill(struct tasklet_struct *t)
 
 EXPORT_SYMBOL(tasklet_kill);
 
+/*
+ * tasklet_hrtimer
+ */
+
+/*
+ * The trampoline is called when the hrtimer expires. If this is
+ * called from the hrtimer interrupt then we schedule the tasklet as
+ * the timer callback function expects to run in softirq context. If
+ * it's called in softirq context anyway (i.e. high resolution timers
+ * disabled) then the hrtimer callback is called right away.
+ */
+static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer)
+{
+ struct tasklet_hrtimer *ttimer =
+ container_of(timer, struct tasklet_hrtimer, timer);
+
+ if (hrtimer_is_hres_active(timer)) {
+ tasklet_hi_schedule(&ttimer->tasklet);
+ return HRTIMER_NORESTART;
+ }
+ return ttimer->function(timer);
+}
+
+/*
+ * Helper function which calls the hrtimer callback from
+ * tasklet/softirq context
+ */
+static void __tasklet_hrtimer_trampoline(unsigned long data)
+{
+ struct tasklet_hrtimer *ttimer = (void *)data;
+ enum hrtimer_restart restart;
+
+ restart = ttimer->function(&ttimer->timer);
+ if (restart != HRTIMER_NORESTART)
+ hrtimer_restart(&ttimer->timer);
+}
+
+/**
+ * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks
+ * @ttimer: tasklet_hrtimer which is initialized
+ * @function: hrtimer callback funtion which gets called from softirq context
+ * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME)
+ * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL)
+ */
+void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
+  enum hrtimer_restart (*function)(struct hrtimer *),
+  clockid_t which_clock, enum hrtimer_mode mode)
+{
+ hrtimer_init(&ttimer->timer, which_clock, mode);
+ ttimer->timer.function = __hrtimer_tasklet_trampoline;
+ tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline,
+     (unsigned long)ttimer);
+ ttimer->function = function;
+}
+EXPORT_SYMBOL_GPL(tasklet_hrtimer_init);
+
+/*
+ * Remote softirq bits
+ */
+
 DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list);
 EXPORT_PER_CPU_SYMBOL(softirq_work_list);
 
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[David Miller-13]

From: Peter Zijlstra <peterz@...>
Date: Wed, 22 Jul 2009 14:28:44 +0200

> Thomas, will you take this?
>
> ---
> Subject: softirq: tasklet_hrtimer
> From: Peter Zijlstra <a.p.zijlstra@...>
> Date: Wed Jul 22 14:18:35 CEST 2009
>
> Stick tasklets and hrtimers together to provide an in-softirq hrtimer
> experience.
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...>

Acked-by: David S. Miller <davem@...>
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[Linus Torvalds-3]

On Wed, 22 Jul 2009, Peter Zijlstra wrote:
>
> Stick tasklets and hrtimers together to provide an in-softirq hrtimer
> experience.
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...>

Looks ok by me now.

Acked-by: Linus Torvalds <torvalds@...>

        Thanks,
                Linus
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