Patch "PM / wakeirq: Convert to SRCU" has been added to the 4.9-stable tree

Patch "PM / wakeirq: Convert to SRCU" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    PM / wakeirq: Convert to SRCU

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pm-wakeirq-convert-to-srcu.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ea0212f40c6bc0594c8eff79266759e3ecd4bacc Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 25 Jun 2017 19:31:13 +0200
Subject: PM / wakeirq: Convert to SRCU

From: Thomas Gleixner <tglx@linutronix.de>

commit ea0212f40c6bc0594c8eff79266759e3ecd4bacc upstream.

The wakeirq infrastructure uses RCU to protect the list of wakeirqs. That
breaks the irq bus locking infrastructure, which is allows sleeping
functions to be called so interrupt controllers behind slow busses,
e.g. i2c, can be handled.

The wakeirq functions hold rcu_read_lock and call into irq functions, which
in case of interrupts using the irq bus locking will trigger a
might_sleep() splat.

Convert the wakeirq infrastructure to Sleepable RCU and unbreak it.

Fixes: 4990d4fe327b (PM / Wakeirq: Add automated device wake IRQ handling)
Reported-by: Brian Norris <briannorris@chromium.org>
Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/base/power/wakeup.c |   32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -60,6 +60,8 @@ static LIST_HEAD(wakeup_sources);
 
 static DECLARE_WAIT_QUEUE_HEAD(wakeup_count_wait_queue);
 
+DEFINE_STATIC_SRCU(wakeup_srcu);
+
 static struct wakeup_source deleted_ws = {
 	.name = "deleted",
 	.lock =  __SPIN_LOCK_UNLOCKED(deleted_ws.lock),
@@ -198,7 +200,7 @@ void wakeup_source_remove(struct wakeup_
 	spin_lock_irqsave(&events_lock, flags);
 	list_del_rcu(&ws->entry);
 	spin_unlock_irqrestore(&events_lock, flags);
-	synchronize_rcu();
+	synchronize_srcu(&wakeup_srcu);
 }
 EXPORT_SYMBOL_GPL(wakeup_source_remove);
 
@@ -332,12 +334,12 @@ void device_wakeup_detach_irq(struct dev
 void device_wakeup_arm_wake_irqs(void)
 {
 	struct wakeup_source *ws;
+	int srcuidx;
 
-	rcu_read_lock();
+	srcuidx = srcu_read_lock(&wakeup_srcu);
 	list_for_each_entry_rcu(ws, &wakeup_sources, entry)
 		dev_pm_arm_wake_irq(ws->wakeirq);
-
-	rcu_read_unlock();
+	srcu_read_unlock(&wakeup_srcu, srcuidx);
 }
 
 /**
@@ -348,12 +350,12 @@ void device_wakeup_arm_wake_irqs(void)
 void device_wakeup_disarm_wake_irqs(void)
 {
 	struct wakeup_source *ws;
+	int srcuidx;
 
-	rcu_read_lock();
+	srcuidx = srcu_read_lock(&wakeup_srcu);
 	list_for_each_entry_rcu(ws, &wakeup_sources, entry)
 		dev_pm_disarm_wake_irq(ws->wakeirq);
-
-	rcu_read_unlock();
+	srcu_read_unlock(&wakeup_srcu, srcuidx);
 }
 
 /**
@@ -805,10 +807,10 @@ EXPORT_SYMBOL_GPL(pm_wakeup_event);
 void pm_print_active_wakeup_sources(void)
 {
 	struct wakeup_source *ws;
-	int active = 0;
+	int srcuidx, active = 0;
 	struct wakeup_source *last_activity_ws = NULL;
 
-	rcu_read_lock();
+	srcuidx = srcu_read_lock(&wakeup_srcu);
 	list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
 		if (ws->active) {
 			pr_info("active wakeup source: %s\n", ws->name);
@@ -824,7 +826,7 @@ void pm_print_active_wakeup_sources(void
 	if (!active && last_activity_ws)
 		pr_info("last active wakeup source: %s\n",
 			last_activity_ws->name);
-	rcu_read_unlock();
+	srcu_read_unlock(&wakeup_srcu, srcuidx);
 }
 EXPORT_SYMBOL_GPL(pm_print_active_wakeup_sources);
 
@@ -951,8 +953,9 @@ void pm_wakep_autosleep_enabled(bool set
 {
 	struct wakeup_source *ws;
 	ktime_t now = ktime_get();
+	int srcuidx;
 
-	rcu_read_lock();
+	srcuidx = srcu_read_lock(&wakeup_srcu);
 	list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
 		spin_lock_irq(&ws->lock);
 		if (ws->autosleep_enabled != set) {
@@ -966,7 +969,7 @@ void pm_wakep_autosleep_enabled(bool set
 		}
 		spin_unlock_irq(&ws->lock);
 	}
-	rcu_read_unlock();
+	srcu_read_unlock(&wakeup_srcu, srcuidx);
 }
 #endif /* CONFIG_PM_AUTOSLEEP */
 
@@ -1027,15 +1030,16 @@ static int print_wakeup_source_stats(str
 static int wakeup_sources_stats_show(struct seq_file *m, void *unused)
 {
 	struct wakeup_source *ws;
+	int srcuidx;
 
 	seq_puts(m, "name\t\tactive_count\tevent_count\twakeup_count\t"
 		"expire_count\tactive_since\ttotal_time\tmax_time\t"
 		"last_change\tprevent_suspend_time\n");
 
-	rcu_read_lock();
+	srcuidx = srcu_read_lock(&wakeup_srcu);
 	list_for_each_entry_rcu(ws, &wakeup_sources, entry)
 		print_wakeup_source_stats(m, ws);
-	rcu_read_unlock();
+	srcu_read_unlock(&wakeup_srcu, srcuidx);
 
 	print_wakeup_source_stats(m, &deleted_ws);
 


Patches currently in stable-queue which might be from tglx@linutronix.de are

queue-4.9/binfmt_elf-use-elf_et_dyn_base-only-for-pie.patch
queue-4.9/revert-sched-core-optimize-sched_smt.patch
queue-4.9/pm-wakeirq-convert-to-srcu.patch
queue-4.9/arm-move-elf_et_dyn_base-to-4mb.patch
queue-4.9/sched-topology-fix-building-of-overlapping-sched-groups.patch
queue-4.9/sched-topology-fix-overlapping-sched_group_mask.patch
queue-4.9/kernel-extable.c-mark-core_kernel_text-notrace.patch
queue-4.9/tools-lib-lockdep-reduce-max_lock_depth-to-avoid-overflowing-lock_chain-depth.patch