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Message-ID: <20140717112458.244fffd1@gandalf.local.home>
Date: Thu, 17 Jul 2014 11:24:58 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: LKML <linux-kernel@...r.kernel.org>,
linux-rt-users <linux-rt-users@...r.kernel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>,
Carsten Emde <C.Emde@...dl.org>,
John Kacur <jkacur@...hat.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [ANNOUNCE] 3.12.24-rt38
Dear RT Folks,
I'm pleased to announce the 3.12.24-rt38 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
branch: v3.12-rt
Head SHA1: e0c7cbcada84aa70709673b0d0fba0ca5d11cb01
Or to build 3.12.24-rt38 directly, the following patches should be applied:
http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.12.tar.xz
http://www.kernel.org/pub/linux/kernel/v3.x/patch-3.12.24.xz
http://www.kernel.org/pub/linux/kernel/projects/rt/3.12/patch-3.12.24-rt38.patch.xz
You can also build from 3.12.24-rt37 by applying the incremental patch:
http://www.kernel.org/pub/linux/kernel/projects/rt/3.12/incr/patch-3.12.24-rt37-rt38.patch.xz
Enjoy,
-- Steve
Changes from v3.12.24-rt37:
---
Steven Rostedt (1):
sched: Do not clear PF_NO_SETAFFINITY flag in select_fallback_rq()
Steven Rostedt (Red Hat) (1):
Linux 3.12.24-rt38
Thomas Gleixner (1):
workqueue: Prevent deadlock/stall on RT
----
kernel/sched/core.c | 13 +++++-------
kernel/workqueue.c | 61 +++++++++++++++++++++++++++++++++++++++++------------
localversion-rt | 2 +-
3 files changed, 54 insertions(+), 22 deletions(-)
---------------------------
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f6f3b3d72578..5e741c96af15 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1289,12 +1289,6 @@ out:
}
}
- /*
- * Clear PF_NO_SETAFFINITY, otherwise we wreckage
- * migrate_disable/enable. See optimization for
- * PF_NO_SETAFFINITY tasks there.
- */
- p->flags &= ~PF_NO_SETAFFINITY;
return dest_cpu;
}
@@ -2651,9 +2645,8 @@ need_resched:
static inline void sched_submit_work(struct task_struct *tsk)
{
- if (!tsk->state || tsk_is_pi_blocked(tsk))
+ if (!tsk->state)
return;
-
/*
* If a worker went to sleep, notify and ask workqueue whether
* it wants to wake up a task to maintain concurrency.
@@ -2661,6 +2654,10 @@ static inline void sched_submit_work(struct task_struct *tsk)
if (tsk->flags & PF_WQ_WORKER)
wq_worker_sleeping(tsk);
+
+ if (tsk_is_pi_blocked(tsk))
+ return;
+
/*
* If we are going to sleep and we have plugged IO queued,
* make sure to submit it to avoid deadlocks.
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index be0ef50a2395..505b55b3c7ae 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -126,6 +126,11 @@ enum {
* cpu or grabbing pool->lock is enough for read access. If
* POOL_DISASSOCIATED is set, it's identical to L.
*
+ * On RT we need the extra protection via rt_lock_idle_list() for
+ * the list manipulations against read access from
+ * wq_worker_sleeping(). All other places are nicely serialized via
+ * pool->lock.
+ *
* MG: pool->manager_mutex and pool->lock protected. Writes require both
* locks. Reads can happen under either lock.
*
@@ -409,6 +414,31 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to,
if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
else
+#ifdef CONFIG_PREEMPT_RT_BASE
+static inline void rt_lock_idle_list(struct worker_pool *pool)
+{
+ preempt_disable();
+}
+static inline void rt_unlock_idle_list(struct worker_pool *pool)
+{
+ preempt_enable();
+}
+static inline void sched_lock_idle_list(struct worker_pool *pool) { }
+static inline void sched_unlock_idle_list(struct worker_pool *pool) { }
+#else
+static inline void rt_lock_idle_list(struct worker_pool *pool) { }
+static inline void rt_unlock_idle_list(struct worker_pool *pool) { }
+static inline void sched_lock_idle_list(struct worker_pool *pool)
+{
+ spin_lock_irq(&pool->lock);
+}
+static inline void sched_unlock_idle_list(struct worker_pool *pool)
+{
+ spin_unlock_irq(&pool->lock);
+}
+#endif
+
+
#ifdef CONFIG_DEBUG_OBJECTS_WORK
static struct debug_obj_descr work_debug_descr;
@@ -801,10 +831,16 @@ static struct worker *first_worker(struct worker_pool *pool)
*/
static void wake_up_worker(struct worker_pool *pool)
{
- struct worker *worker = first_worker(pool);
+ struct worker *worker;
+
+ rt_lock_idle_list(pool);
+
+ worker = first_worker(pool);
if (likely(worker))
wake_up_process(worker->task);
+
+ rt_unlock_idle_list(pool);
}
/**
@@ -832,7 +868,7 @@ void wq_worker_running(struct task_struct *task)
*/
void wq_worker_sleeping(struct task_struct *task)
{
- struct worker *next, *worker = kthread_data(task);
+ struct worker *worker = kthread_data(task);
struct worker_pool *pool;
/*
@@ -849,25 +885,18 @@ void wq_worker_sleeping(struct task_struct *task)
return;
worker->sleeping = 1;
- spin_lock_irq(&pool->lock);
+
/*
* The counterpart of the following dec_and_test, implied mb,
* worklist not empty test sequence is in insert_work().
* Please read comment there.
- *
- * NOT_RUNNING is clear. This means that we're bound to and
- * running on the local cpu w/ rq lock held and preemption
- * disabled, which in turn means that none else could be
- * manipulating idle_list, so dereferencing idle_list without pool
- * lock is safe.
*/
if (atomic_dec_and_test(&pool->nr_running) &&
!list_empty(&pool->worklist)) {
- next = first_worker(pool);
- if (next)
- wake_up_process(next->task);
+ sched_lock_idle_list(pool);
+ wake_up_worker(pool);
+ sched_unlock_idle_list(pool);
}
- spin_unlock_irq(&pool->lock);
}
/**
@@ -1571,7 +1600,9 @@ static void worker_enter_idle(struct worker *worker)
worker->last_active = jiffies;
/* idle_list is LIFO */
+ rt_lock_idle_list(pool);
list_add(&worker->entry, &pool->idle_list);
+ rt_unlock_idle_list(pool);
if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
@@ -1604,7 +1635,9 @@ static void worker_leave_idle(struct worker *worker)
return;
worker_clr_flags(worker, WORKER_IDLE);
pool->nr_idle--;
+ rt_lock_idle_list(pool);
list_del_init(&worker->entry);
+ rt_unlock_idle_list(pool);
}
/**
@@ -1849,7 +1882,9 @@ static void destroy_worker(struct worker *worker)
*/
get_task_struct(worker->task);
+ rt_lock_idle_list(pool);
list_del_init(&worker->entry);
+ rt_unlock_idle_list(pool);
worker->flags |= WORKER_DIE;
idr_remove(&pool->worker_idr, worker->id);
diff --git a/localversion-rt b/localversion-rt
index a3b2408c1da6..49bae8d6aa67 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt37
+-rt38
--
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