[ANNOUNCE] 3.4.24-rt36

From: Steven Rostedt
Date: Thu Dec 27 2012 - 10:48:02 EST



Dear RT Folks,

I'm pleased to announce the 3.4.24-rt36 stable release.


You can get this release via the git tree at:

git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git

Head SHA1: c094034cc852ce529317bddff5bda479aed11385


Or to build 3.4.24-rt36 directly, the following patches should be applied:

http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.4.tar.xz

http://www.kernel.org/pub/linux/kernel/v3.x/patch-3.4.24.xz

http://www.kernel.org/pub/linux/kernel/projects/rt/3.4/patch-3.4.24-rt36.patch.xz


You can also build from 3.4.24-rt35 by applying the incremental patch:

http://www.kernel.org/pub/linux/kernel/projects/rt/3.4/incr/patch-3.4.24-rt35-rt36.patch.xz



Enjoy,

-- Steve


Changes from 3.4.24-rt35:

---

Steven Rostedt (1):
Linux 3.4.24-rt36

Thomas Gleixner (4):
sched: Adjust sched_reset_on_fork when nothing else changes
sched: Queue RT tasks to head when prio drops
sched: Consider pi boosting in setscheduler
block: Use cpu_chill() for retry loops

----
block/blk-ioc.c | 5 +++--
include/linux/sched.h | 5 +++++
kernel/rtmutex.c | 12 +++++++++++
kernel/sched/core.c | 55 +++++++++++++++++++++++++++++++++++++------------
localversion-rt | 2 +-
5 files changed, 63 insertions(+), 16 deletions(-)
---------------------------
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index fb95dd2..6b54201 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -8,6 +8,7 @@
#include <linux/blkdev.h>
#include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
#include <linux/slab.h>
+#include <linux/delay.h>

#include "blk.h"

@@ -110,7 +111,7 @@ static void ioc_release_fn(struct work_struct *work)
spin_unlock(q->queue_lock);
} else {
spin_unlock_irqrestore(&ioc->lock, flags);
- cpu_relax();
+ cpu_chill();
spin_lock_irqsave_nested(&ioc->lock, flags, 1);
}
}
@@ -188,7 +189,7 @@ retry:
spin_unlock(icq->q->queue_lock);
} else {
spin_unlock_irqrestore(&ioc->lock, flags);
- cpu_relax();
+ cpu_chill();
goto retry;
}
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f291347..b0448fa 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2166,6 +2166,7 @@ extern unsigned int sysctl_sched_cfs_bandwidth_slice;
#ifdef CONFIG_RT_MUTEXES
extern int rt_mutex_getprio(struct task_struct *p);
extern void rt_mutex_setprio(struct task_struct *p, int prio);
+extern int rt_mutex_check_prio(struct task_struct *task, int newprio);
extern void rt_mutex_adjust_pi(struct task_struct *p);
static inline bool tsk_is_pi_blocked(struct task_struct *tsk)
{
@@ -2176,6 +2177,10 @@ static inline int rt_mutex_getprio(struct task_struct *p)
{
return p->normal_prio;
}
+static inline int rt_mutex_check_prio(struct task_struct *task, int newprio)
+{
+ return 0;
+}
# define rt_mutex_adjust_pi(p) do { } while (0)
static inline bool tsk_is_pi_blocked(struct task_struct *tsk)
{
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index 3bff726..20742e7 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -124,6 +124,18 @@ int rt_mutex_getprio(struct task_struct *task)
}

/*
+ * Called by sched_setscheduler() to check whether the priority change
+ * is overruled by a possible priority boosting.
+ */
+int rt_mutex_check_prio(struct task_struct *task, int newprio)
+{
+ if (!task_has_pi_waiters(task))
+ return 0;
+
+ return task_top_pi_waiter(task)->pi_list_entry.prio <= newprio;
+}
+
+/*
* Adjust the priority of a task, after its pi_waiters got modified.
*
* This can be both boosting and unboosting. task->pi_lock must be held.
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1f9d6f5..7b501a3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4085,7 +4085,8 @@ EXPORT_SYMBOL(sleep_on_timeout);
* This function changes the 'effective' priority of a task. It does
* not touch ->normal_prio like __setscheduler().
*
- * Used by the rt_mutex code to implement priority inheritance logic.
+ * Used by the rt_mutex code to implement priority inheritance
+ * logic. Call site only calls if the priority of the task changed.
*/
void rt_mutex_setprio(struct task_struct *p, int prio)
{
@@ -4308,20 +4309,25 @@ static struct task_struct *find_process_by_pid(pid_t pid)
return pid ? find_task_by_vpid(pid) : current;
}

-/* Actually do priority change: must hold rq lock. */
-static void
-__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
+static void __setscheduler_params(struct task_struct *p, int policy, int prio)
{
p->policy = policy;
p->rt_priority = prio;
p->normal_prio = normal_prio(p);
+ set_load_weight(p);
+}
+
+/* Actually do priority change: must hold rq lock. */
+static void
+__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
+{
+ __setscheduler_params(p, policy, prio);
/* we are holding p->pi_lock already */
p->prio = rt_mutex_getprio(p);
if (rt_prio(p->prio))
p->sched_class = &rt_sched_class;
else
p->sched_class = &fair_sched_class;
- set_load_weight(p);
}

/*
@@ -4346,6 +4352,7 @@ static bool check_same_owner(struct task_struct *p)
static int __sched_setscheduler(struct task_struct *p, int policy,
const struct sched_param *param, bool user)
{
+ int newprio = MAX_RT_PRIO - 1 - param->sched_priority;
int retval, oldprio, oldpolicy = -1, on_rq, running;
unsigned long flags;
const struct sched_class *prev_class;
@@ -4441,11 +4448,13 @@ recheck:
}

/*
- * If not changing anything there's no need to proceed further:
+ * If not changing anything there's no need to proceed
+ * further, but store a possible modification of
+ * reset_on_fork.
*/
if (unlikely(policy == p->policy && (!rt_policy(policy) ||
param->sched_priority == p->rt_priority))) {
-
+ p->sched_reset_on_fork = reset_on_fork;
__task_rq_unlock(rq);
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
return 0;
@@ -4472,6 +4481,25 @@ recheck:
task_rq_unlock(rq, p, &flags);
goto recheck;
}
+
+ p->sched_reset_on_fork = reset_on_fork;
+ oldprio = p->prio;
+
+ /*
+ * Special case for priority boosted tasks.
+ *
+ * If the new priority is lower or equal (user space view)
+ * than the current (boosted) priority, we just store the new
+ * normal parameters and do not touch the scheduler class and
+ * the runqueue. This will be done when the task deboost
+ * itself.
+ */
+ if (rt_mutex_check_prio(p, newprio)) {
+ __setscheduler_params(p, policy, param->sched_priority);
+ task_rq_unlock(rq, p, &flags);
+ return 0;
+ }
+
on_rq = p->on_rq;
running = task_current(rq, p);
if (on_rq)
@@ -4479,17 +4507,18 @@ 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);
-
+ if (on_rq) {
+ /*
+ * We enqueue to tail when the priority of a task is
+ * increased (user space view).
+ */
+ enqueue_task(rq, p, oldprio <= p->prio ? ENQUEUE_HEAD : 0);
+ }
check_class_changed(rq, p, prev_class, oldprio);
task_rq_unlock(rq, p, &flags);

diff --git a/localversion-rt b/localversion-rt
index 366440d..2294034 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt35
+-rt36


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