[ANNOUNCE] 3.6.9-rt21

[ANNOUNCE] 3.6.9-rt21

[Thomas Gleixner]

Dear RT Folks,

I'm pleased to announce the 3.6.9-rt21 release. 3.6.7-rt18, 3.6.8-rt19
and 3.6.9-rt20 are not announced updates to the respective 3.6.y
stable releases without any RT changes

Changes since 3.6.9-rt20:

   * Fix the PREEMPT_LAZY implementation on ARM

   * Fix the RCUTINY issues

   * Fix a long standing scheduler bug (See commit log of
     sched-enqueue-to-head.patch)


Known issues:

   * There is still a possibility to get false positives from the NOHZ
     idle softirq pending detector. It's rather complex to fix and I
     have postponed it for a separate release. The warnings are
     harmless and can be ignored for now.

The delta patch against 3.6.9-rt20 is appended below and can be found
here:

  http://www.kernel.org/pub/linux/kernel/projects/rt/3.6/incr/patch-3.6.9-rt20-rt21.patch.xz

The RT patch against 3.6.9 can be found here:

  http://www.kernel.org/pub/linux/kernel/projects/rt/3.6/patch-3.6.9-rt21.patch.xz

The split quilt queue is available at:

  http://www.kernel.org/pub/linux/kernel/projects/rt/3.6/patches-3.6.9-rt21.tar.xz

Enjoy,

	tglx

------------->
Index: linux-stable/arch/arm/kernel/entry-armv.S
===================================================================
--- linux-stable.orig/arch/arm/kernel/entry-armv.S
+++ linux-stable/arch/arm/kernel/entry-armv.S
@@ -216,17 +216,18 @@ __irq_svc:
 #ifdef CONFIG_PREEMPT
 	get_thread_info tsk
 	ldr	r8, [tsk, #TI_PREEMPT]		@ get preempt count
-	ldr	r0, [tsk, #TI_FLAGS]		@ get flags
 	teq	r8, #0				@ if preempt count != 0
-	movne	r0, #0				@ force flags to 0
-	tst	r0, #_TIF_NEED_RESCHED
-	blne	svc_preempt
-	ldr	r8, [tsk, #TI_PREEMPT_LAZY]	@ get preempt lazy count
+	bne	1f				@ return from exeption
 	ldr	r0, [tsk, #TI_FLAGS]		@ get flags
+	tst	r0, #_TIF_NEED_RESCHED		@ if NEED_RESCHED is set
+	blne	svc_preempt			@ preempt!
+
+	ldr	r8, [tsk, #TI_PREEMPT_LAZY]	@ get preempt lazy count
 	teq	r8, #0				@ if preempt lazy count != 0
 	movne	r0, #0				@ force flags to 0
 	tst	r0, #_TIF_NEED_RESCHED_LAZY
 	blne	svc_preempt
+1:
 #endif
 
 #ifdef CONFIG_TRACE_IRQFLAGS
Index: linux-stable/kernel/Makefile
===================================================================
--- linux-stable.orig/kernel/Makefile
+++ linux-stable/kernel/Makefile
@@ -10,7 +10,7 @@ obj-y     = fork.o exec_domain.o panic.o
 	    kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o \
 	    hrtimer.o nsproxy.o srcu.o semaphore.o \
 	    notifier.o ksysfs.o cred.o \
-	    async.o range.o groups.o lglock.o
+	    async.o range.o groups.o lglock.o wait-simple.o
 
 ifdef CONFIG_FUNCTION_TRACER
 # Do not trace debug files and internal ftrace files
Index: linux-stable/kernel/rcutiny_plugin.h
===================================================================
--- linux-stable.orig/kernel/rcutiny_plugin.h
+++ linux-stable/kernel/rcutiny_plugin.h
@@ -26,6 +26,7 @@
 #include <linux/module.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
+#include <linux/wait-simple.h>
 
 /* Global control variables for rcupdate callback mechanism. */
 struct rcu_ctrlblk {
@@ -260,7 +261,7 @@ static void show_tiny_preempt_stats(stru
 
 /* Controls for rcu_kthread() kthread. */
 static struct task_struct *rcu_kthread_task;
-static DECLARE_WAIT_QUEUE_HEAD(rcu_kthread_wq);
+static DEFINE_SWAIT_HEAD(rcu_kthread_wq);
 static unsigned long have_rcu_kthread_work;
 
 /*
@@ -710,7 +711,7 @@ void synchronize_rcu(void)
 }
 EXPORT_SYMBOL_GPL(synchronize_rcu);
 
-static DECLARE_WAIT_QUEUE_HEAD(sync_rcu_preempt_exp_wq);
+static DEFINE_SWAIT_HEAD(sync_rcu_preempt_exp_wq);
 static unsigned long sync_rcu_preempt_exp_count;
 static DEFINE_MUTEX(sync_rcu_preempt_exp_mutex);
 
@@ -732,7 +733,7 @@ static int rcu_preempted_readers_exp(voi
  */
 static void rcu_report_exp_done(void)
 {
-	wake_up(&sync_rcu_preempt_exp_wq);
+	swait_wake(&sync_rcu_preempt_exp_wq);
 }
 
 /*
@@ -784,8 +785,8 @@ void synchronize_rcu_expedited(void)
 	} else {
 		rcu_initiate_boost();
 		local_irq_restore(flags);
-		wait_event(sync_rcu_preempt_exp_wq,
-			   !rcu_preempted_readers_exp());
+		swait_event(sync_rcu_preempt_exp_wq,
+			    !rcu_preempted_readers_exp());
 	}
 
 	/* Clean up and exit. */
@@ -855,7 +856,7 @@ static void invoke_rcu_callbacks(void)
 {
 	have_rcu_kthread_work = 1;
 	if (rcu_kthread_task != NULL)
-		wake_up(&rcu_kthread_wq);
+		swait_wake(&rcu_kthread_wq);
 }
 
 #ifdef CONFIG_RCU_TRACE
@@ -885,8 +886,8 @@ static int rcu_kthread(void *arg)
 	unsigned long flags;
 
 	for (;;) {
-		wait_event_interruptible(rcu_kthread_wq,
-					 have_rcu_kthread_work != 0);
+		swait_event_interruptible(rcu_kthread_wq,
+					  have_rcu_kthread_work != 0);
 		morework = rcu_boost();
 		local_irq_save(flags);
 		work = have_rcu_kthread_work;
Index: linux-stable/kernel/sched/core.c
===================================================================
--- linux-stable.orig/kernel/sched/core.c
+++ linux-stable/kernel/sched/core.c
@@ -4268,6 +4268,8 @@ void rt_mutex_setprio(struct task_struct
 
 	trace_sched_pi_setprio(p, prio);
 	oldprio = p->prio;
+	if (oldprio == prio)
+		goto out_unlock;
 	prev_class = p->sched_class;
 	on_rq = p->on_rq;
 	running = task_current(rq, p);
@@ -4618,6 +4620,13 @@ recheck:
 		task_rq_unlock(rq, p, &flags);
 		goto recheck;
 	}
+
+	p->sched_reset_on_fork = reset_on_fork;
+
+	oldprio = p->prio;
+	if (oldprio == param->sched_priority)
+		goto out;
+
 	on_rq = p->on_rq;
 	running = task_current(rq, p);
 	if (on_rq)
@@ -4625,18 +4634,17 @@ recheck:
 	if (running)
 		p->sched_class->put_prev_task(rq, p);
 
-	p->sched_reset_on_fork = reset_on_fork;
-
-	oldprio = p->prio;
 	prev_class = p->sched_class;
 	__setscheduler(rq, p, policy, param->sched_priority);
 
 	if (running)
 		p->sched_class->set_curr_task(rq);
 	if (on_rq)
-		enqueue_task(rq, p, 0);
+		enqueue_task(rq, p, oldprio < param->sched_priority ?
+			     ENQUEUE_HEAD : 0);
 
 	check_class_changed(rq, p, prev_class, oldprio);
+out:
 	task_rq_unlock(rq, p, &flags);
 
 	rt_mutex_adjust_pi(p);
Index: linux-stable/localversion-rt
===================================================================
--- linux-stable.orig/localversion-rt
+++ linux-stable/localversion-rt
@@ -1 +1 @@
--rt20
+-rt21
Index: linux-stable/include/linux/wait-simple.h
===================================================================
--- /dev/null
+++ linux-stable/include/linux/wait-simple.h
@@ -0,0 +1,204 @@
+#ifndef _LINUX_WAIT_SIMPLE_H
+#define _LINUX_WAIT_SIMPLE_H
+
+#include <linux/spinlock.h>
+#include <linux/list.h>
+
+#include <asm/current.h>
+
+struct swaiter {
+	struct task_struct	*task;
+	struct list_head	node;
+};
+
+#define DEFINE_SWAITER(name)					\
+	struct swaiter name = {					\
+		.task	= current,				\
+		.node	= LIST_HEAD_INIT((name).node),		\
+	}
+
+struct swait_head {
+	raw_spinlock_t		lock;
+	struct list_head	list;
+};
+
+#define DEFINE_SWAIT_HEAD(name)					\
+	struct swait_head name = {				\
+		.lock	= __RAW_SPIN_LOCK_UNLOCKED(name.lock),	\
+		.list	= LIST_HEAD_INIT((name).list),		\
+	}
+
+extern void __init_swait_head(struct swait_head *h, struct lock_class_key *key);
+
+#define init_swait_head(swh)					\
+	do {							\
+		static struct lock_class_key __key;		\
+								\
+		__init_swait_head((swh), &__key);		\
+	} while (0)
+
+/*
+ * Waiter functions
+ */
+static inline bool swaiter_enqueued(struct swaiter *w)
+{
+	return w->task != NULL;
+}
+
+extern void swait_prepare(struct swait_head *head, struct swaiter *w, int state);
+extern void swait_finish(struct swait_head *head, struct swaiter *w);
+
+/*
+ * Adds w to head->list. Must be called with head->lock locked.
+ */
+static inline void __swait_enqueue(struct swait_head *head, struct swaiter *w)
+{
+	list_add(&w->node, &head->list);
+}
+
+/*
+ * Removes w from head->list. Must be called with head->lock locked.
+ */
+static inline void __swait_dequeue(struct swaiter *w)
+{
+	list_del_init(&w->node);
+}
+
+/*
+ * Check whether a head has waiters enqueued
+ */
+static inline bool swait_head_has_waiters(struct swait_head *h)
+{
+	return !list_empty(&h->list);
+}
+
+/*
+ * Wakeup functions
+ */
+extern int __swait_wake(struct swait_head *head, unsigned int state);
+
+static inline int swait_wake(struct swait_head *head)
+{
+	return swait_head_has_waiters(head) ?
+		__swait_wake(head, TASK_NORMAL) : 0;
+}
+
+static inline int swait_wake_interruptible(struct swait_head *head)
+{
+	return swait_head_has_waiters(head) ?
+		__swait_wake(head, TASK_INTERRUPTIBLE) : 0;
+}
+
+/*
+ * Event API
+ */
+
+#define __swait_event(wq, condition)					\
+do {									\
+	DEFINE_SWAITER(__wait);						\
+									\
+	for (;;) {							\
+		swait_prepare(&wq, &__wait, TASK_UNINTERRUPTIBLE);	\
+		if (condition)						\
+			break;						\
+		schedule();						\
+	}								\
+	swait_finish(&wq, &__wait);					\
+} while (0)
+
+/**
+ * swait_event - sleep until a condition gets true
+ * @wq: the waitqueue to wait on
+ * @condition: a C expression for the event to wait for
+ *
+ * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
+ * @condition evaluates to true. The @condition is checked each time
+ * the waitqueue @wq is woken up.
+ *
+ * wake_up() has to be called after changing any variable that could
+ * change the result of the wait condition.
+ */
+#define swait_event(wq, condition)					\
+do {									\
+	if (condition)							\
+		break;							\
+	__swait_event(wq, condition);					\
+} while (0)
+
+#define __swait_event_interruptible(wq, condition, ret)			\
+do {									\
+	DEFINE_SWAITER(__wait);						\
+									\
+	for (;;) {							\
+		swait_prepare(&wq, &__wait, TASK_INTERRUPTIBLE);	\
+		if (condition)						\
+			break;						\
+		if (signal_pending(current)) {				\
+			ret = -ERESTARTSYS;				\
+			break;						\
+		}							\
+		schedule();						\
+	}								\
+	swait_finish(&wq, &__wait);					\
+} while (0)
+
+/**
+ * swait_event_interruptible - sleep until a condition gets true
+ * @wq: the waitqueue to wait on
+ * @condition: a C expression for the event to wait for
+ *
+ * The process is put to sleep (TASK_INTERRUPTIBLE) until the
+ * @condition evaluates to true. The @condition is checked each time
+ * the waitqueue @wq is woken up.
+ *
+ * wake_up() has to be called after changing any variable that could
+ * change the result of the wait condition.
+ */
+#define swait_event_interruptible(wq, condition)			\
+({									\
+	int __ret = 0;							\
+	if (!(condition))						\
+		__swait_event_interruptible(wq, condition, __ret);	\
+	__ret;								\
+})
+
+#define __swait_event_timeout(wq, condition, ret)			\
+do {									\
+	DEFINE_SWAITER(__wait);						\
+									\
+	for (;;) {							\
+		swait_prepare(&wq, &__wait, TASK_UNINTERRUPTIBLE);	\
+		if (condition)						\
+			break;						\
+		ret = schedule_timeout(ret);				\
+		if (!ret)						\
+			break;						\
+	}								\
+	swait_finish(&wq, &__wait);					\
+} while (0)
+
+/**
+ * swait_event_timeout - sleep until a condition gets true or a timeout elapses
+ * @wq: the waitqueue to wait on
+ * @condition: a C expression for the event to wait for
+ * @timeout: timeout, in jiffies
+ *
+ * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
+ * @condition evaluates to true. The @condition is checked each time
+ * the waitqueue @wq is woken up.
+ *
+ * wake_up() has to be called after changing any variable that could
+ * change the result of the wait condition.
+ *
+ * The function returns 0 if the @timeout elapsed, and the remaining
+ * jiffies if the condition evaluated to true before the timeout elapsed.
+ */
+#define swait_event_timeout(wq, condition, timeout)			\
+({									\
+	long __ret = timeout;						\
+	if (!(condition))						\
+		__swait_event_timeout(wq, condition, __ret);		\
+	__ret;								\
+})
+
+#endif
Index: linux-stable/kernel/wait-simple.c
===================================================================
--- /dev/null
+++ linux-stable/kernel/wait-simple.c
@@ -0,0 +1,68 @@
+/*
+ * Simple waitqueues without fancy flags and callbacks
+ *
+ * (C) 2011 Thomas Gleixner <tglx@linutronix.de>
+ *
+ * Based on kernel/wait.c
+ *
+ * For licencing details see kernel-base/COPYING
+ */
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/wait-simple.h>
+
+void __init_swait_head(struct swait_head *head, struct lock_class_key *key)
+{
+	raw_spin_lock_init(&head->lock);
+	lockdep_set_class(&head->lock, key);
+	INIT_LIST_HEAD(&head->list);
+}
+EXPORT_SYMBOL_GPL(__init_swait_head);
+
+void swait_prepare(struct swait_head *head, struct swaiter *w, int state)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&head->lock, flags);
+	w->task = current;
+	if (list_empty(&w->node))
+		__swait_enqueue(head, w);
+	set_current_state(state);
+	raw_spin_unlock_irqrestore(&head->lock, flags);
+}
+EXPORT_SYMBOL_GPL(swait_prepare);
+
+void swait_finish(struct swait_head *head, struct swaiter *w)
+{
+	unsigned long flags;
+
+	__set_current_state(TASK_RUNNING);
+	if (w->task) {
+		raw_spin_lock_irqsave(&head->lock, flags);
+		__swait_dequeue(w);
+		raw_spin_unlock_irqrestore(&head->lock, flags);
+	}
+}
+EXPORT_SYMBOL_GPL(swait_finish);
+
+int __swait_wake(struct swait_head *head, unsigned int state)
+{
+	struct swaiter *curr, *next;
+	unsigned long flags;
+	int woken = 0;
+
+	raw_spin_lock_irqsave(&head->lock, flags);
+
+	list_for_each_entry_safe(curr, next, &head->list, node) {
+		if (wake_up_state(curr->task, state)) {
+			__swait_dequeue(curr);
+			curr->task = NULL;
+			woken++;
+		}
+	}
+
+	raw_spin_unlock_irqrestore(&head->lock, flags);
+	return woken;
+}
+EXPORT_SYMBOL_GPL(__swait_wake);

Re: [ANNOUNCE] 3.6.9-rt21

[Tim Sander]

Hi Thomas
> I'm pleased to announce the 3.6.9-rt21 release. 3.6.7-rt18, 3.6.8-rt19
> and 3.6.9-rt20 are not announced updates to the respective 3.6.y
> stable releases without any RT changes
There is some progress here. It boots but sometimes i see the backtrace below.

Also: Has s.th. changed in respect to the modules. I have one module wich goes on an 
endless interrupt loop freezing the device. The driver works fine for 3.0  - 3.4 preempt 
rt kernels? This is a miscdev based driver. If someone is interested i can post the source 
over here. But unfortunatly i have not figured out why this thing goes to an endless interrupt.
The identical driver works flawless on 3.4.

As always i have some platform adaptation code applied but nothing serious/different from the 3.4 patches which work fine.

Backtrace: 
[<c00114ec>] (dump_backtrace+0x0/0x110) from [<c029732c>] (dump_stack+0x18/0x1c)
 r6:c0327ca9 r5:00000da5 r4:00000000 r3:c7846080
[<c0297314>] (dump_stack+0x0/0x1c) from [<c001b910>] (warn_slowpath_common+0x54/0x6c)
[<c001b8bc>] (warn_slowpath_common+0x0/0x6c) from [<c001b94c>] (warn_slowpath_null+0x24/0x2c)
 r8:c03b0bc8 r7:c03c5f38 r6:c784e000 r5:60000013 r4:00000000
r3:00000009
[<c001b928>] (warn_slowpath_null+0x0/0x2c) from [<c00533cc>] (check_flags+0xcc/0x12c)
[<c0053300>] (check_flags+0x0/0x12c) from [<c0054ef0>] (lock_is_held+0x3c/0xb4)
[<c0054eb4>] (lock_is_held+0x0/0xb4) from [<c0043ff0>] (__might_sleep+0x40/0x1d0)
 r8:c03b2440 r7:c03c5f38 r6:00000000 r5:c0327ce1 r4:00000481
r3:00000000
[<c0043fb0>] (__might_sleep+0x0/0x1d0) from [<c0299228>] (rt_mutex_lock+0x20/0x40)
 r7:c784ff24 r6:c08c0e80 r5:c784e000 r4:c784ff20
[<c0299208>] (rt_mutex_lock+0x0/0x40) from [<c0068a54>] (rcu_kthread+0x100/0x198)
 r4:c784ff20 r3:c784ff40
[<c0068954>] (rcu_kthread+0x0/0x198) from [<c003be14>] (kthread+0x90/0x9c)
[<c003bd84>] (kthread+0x0/0x9c) from [<c00218e8>] (do_exit+0x0/0x2f0)
 r7:00000013 r6:c00218e8 r5:c003bd84 r4:c782becc
---[ end trace 0000000000000002 ]---
possible reason: unannotated irqs-on.
irq event stamp: 87282
hardirqs last  enabled at (87281): [<c029a1a8>] _raw_spin_unlock_irqrestore+0x44/0x80
hardirqs last disabled at (87282): [<c00541c8>] debug_check_no_locks_freed+0x44/0x154
softirqs last  enabled at (0): [<c001a2fc>] copy_process+0x1f4/0xb78
softirqs last disabled at (0): [<  (null)>]   (null)

Best regards
Tim

Re: [ANNOUNCE] 3.6.9-rt21

[Tim Sander]

Hi
> Also: Has s.th. changed in respect to the modules. I have one module wich
> goes on an endless interrupt loop freezing the device. The driver works
> fine for 3.0  - 3.4 preempt rt kernels? This is a miscdev based driver. If
> someone is interested i can post the source over here. But unfortunatly i
> have not figured out why this thing goes to an endless interrupt. The
> identical driver works flawless on 3.4.

I have just crosschecked with 3.6.9. The same error as with the preempt rt 
version. So it's not an preempt rt problem.

Best regards
Tim

Re: [ANNOUNCE] 3.6.9-rt21

[Ove Karlsen]

Heya. As some may remember, I said I was going to build an E5 machine. 
Well I did, well atleast ordered the most similar to what I wanted, and 
exchanged the graphics-card (pcie3.0) only. I was completely correct in 
that this machine, would have low-jitter
/low-latency. And it completely lives up to expectations. So if you want 
low-jitter (think amiga, if that references means something to you), 
definately get an E5 (with direct i/o).

Threadirqs also works on this computer.

Peace Be With You.

Re: [ANNOUNCE] 3.6.9-rt21

[Ove Karlsen]

On 12/8/2012 4:28 PM, jdow wrote:
> On 2012/12/08 16:48, Ove Karlsen wrote:
>> Heya. As some may remember, I said I was going to build an E5 
>> machine. Well I
>> did, well atleast ordered the most similar to what I wanted, and 
>> exchanged the
>> graphics-card (pcie3.0) only. I was completely correct in that this 
>> machine,
>> would have low-jitter
>> /low-latency. And it completely lives up to expectations. So if you want
>> low-jitter (think amiga, if that references means something to you), 
>> definately
>> get an E5 (with direct i/o).
>>
>> Threadirqs also works on this computer.
>
> Ah, yes, we did do some surprising things with those old boxes. Richmond
> Sound Design had some applications for assisting stage managers in
> theatrical, theme park, and other presentation applications. The jitter
> compared to latency was remarkably low considering the age of the boxes.
>
> {^_-}   We you ever on BIX? (I don't recognize the name, though.)
>     Joanne
Yeah, we have finally caught up, and that is a very good thing. No I was 
never on BIX.

Peace Be WIth You.

Re: [ANNOUNCE] 3.6.9-rt21

[Mike Galbraith]

On Wed, 2012-12-05 at 17:05 +0100, Thomas Gleixner wrote: 
> Dear RT Folks,
> 
> I'm pleased to announce the 3.6.9-rt21 release. 3.6.7-rt18, 3.6.8-rt19
> and 3.6.9-rt20 are not announced updates to the respective 3.6.y
> stable releases without any RT changes
> 
> Changes since 3.6.9-rt20:
> 
>    * Fix the PREEMPT_LAZY implementation on ARM
> 
>    * Fix the RCUTINY issues
> 
>    * Fix a long standing scheduler bug (See commit log of
>      sched-enqueue-to-head.patch)

That last has an oversight buglet.

sched: add missing userspace->kernel struct sched_param.sched_priority inversion

Signed-off-by: Mike Galbraith <bitbucket@online.de>
---
 kernel/sched/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4624,7 +4624,7 @@ static int __sched_setscheduler(struct t
 	p->sched_reset_on_fork = reset_on_fork;
 
 	oldprio = p->prio;
-	if (oldprio == param->sched_priority)
+	if (oldprio == (MAX_RT_PRIO - 1) - param->sched_priority)
 		goto out;
 
 	on_rq = p->on_rq;

Re: [ANNOUNCE] 3.6.9-rt21

[Thomas Gleixner]

On Sat, 15 Dec 2012, Mike Galbraith wrote:
> On Wed, 2012-12-05 at 17:05 +0100, Thomas Gleixner wrote: 
> > Dear RT Folks,
> > 
> > I'm pleased to announce the 3.6.9-rt21 release. 3.6.7-rt18, 3.6.8-rt19
> > and 3.6.9-rt20 are not announced updates to the respective 3.6.y
> > stable releases without any RT changes
> > 
> > Changes since 3.6.9-rt20:
> > 
> >    * Fix the PREEMPT_LAZY implementation on ARM
> > 
> >    * Fix the RCUTINY issues
> > 
> >    * Fix a long standing scheduler bug (See commit log of
> >      sched-enqueue-to-head.patch)
> 
> That last has an oversight buglet.
> 
> sched: add missing userspace->kernel struct sched_param.sched_priority inversion
> 
> Signed-off-by: Mike Galbraith <bitbucket@online.de>
> ---
>  kernel/sched/core.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -4624,7 +4624,7 @@ static int __sched_setscheduler(struct t
>  	p->sched_reset_on_fork = reset_on_fork;
>  
>  	oldprio = p->prio;
> -	if (oldprio == param->sched_priority)
> +	if (oldprio == (MAX_RT_PRIO - 1) - param->sched_priority)
>  		goto out;
>  
>  	on_rq = p->on_rq;

Duh, yes. But there is another one here:

+               enqueue_task(rq, p, oldprio < param->sched_priority ?
+                            ENQUEUE_HEAD : 0);

Bah. This reverse user/kernel priority nonsense really should go away!

Thanks,

	tglx

Re: [ANNOUNCE] 3.6.9-rt21

[Mike Galbraith]

On Mon, 2012-12-17 at 16:35 +0100, Thomas Gleixner wrote: 
> On Sat, 15 Dec 2012, Mike Galbraith wrote:
> > On Wed, 2012-12-05 at 17:05 +0100, Thomas Gleixner wrote: 
> > > Dear RT Folks,
> > > 
> > > I'm pleased to announce the 3.6.9-rt21 release. 3.6.7-rt18, 3.6.8-rt19
> > > and 3.6.9-rt20 are not announced updates to the respective 3.6.y
> > > stable releases without any RT changes
> > > 
> > > Changes since 3.6.9-rt20:
> > > 
> > >    * Fix the PREEMPT_LAZY implementation on ARM
> > > 
> > >    * Fix the RCUTINY issues
> > > 
> > >    * Fix a long standing scheduler bug (See commit log of
> > >      sched-enqueue-to-head.patch)
> > 
> > That last has an oversight buglet.
> > 
> > sched: add missing userspace->kernel struct sched_param.sched_priority inversion
> > 
> > Signed-off-by: Mike Galbraith <bitbucket@online.de>
> > ---
> >  kernel/sched/core.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -4624,7 +4624,7 @@ static int __sched_setscheduler(struct t
> >  	p->sched_reset_on_fork = reset_on_fork;
> >  
> >  	oldprio = p->prio;
> > -	if (oldprio == param->sched_priority)
> > +	if (oldprio == (MAX_RT_PRIO - 1) - param->sched_priority)
> >  		goto out;
> >  
> >  	on_rq = p->on_rq;
> 
> Duh, yes. But there is another one here:
> 
> +               enqueue_task(rq, p, oldprio < param->sched_priority ?
> +                            ENQUEUE_HEAD : 0);
> 
> Bah. This reverse user/kernel priority nonsense really should go away!

Snort, I looked right at it too, looked perfectly fine :)

-Mike

Re: [ANNOUNCE] 3.6.9-rt21

[Thomas Gleixner]

On Mon, 17 Dec 2012, Mike Galbraith wrote:
> On Mon, 2012-12-17 at 16:35 +0100, Thomas Gleixner wrote: 
> > Bah. This reverse user/kernel priority nonsense really should go away!
> 
> Snort, I looked right at it too, looked perfectly fine :)

The real bad news is, that I talked to someone about that reverse prio
issue just a few hours before I committed that crime. Blergh!