On Sun, Jun 25, 2017 at 07:31:13PM +0200, Thomas Gleixner wrote:
> 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 <[email protected]>
> Suggested-by: Paul E. McKenney <[email protected]>
> Signed-off-by: Thomas Gleixner <[email protected]>
Looks good to me!
Reviewed-by: Paul E. McKenney <[email protected]>
> ---
> 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);
> }
>
> /**
> @@ -804,10 +806,10 @@ EXPORT_SYMBOL_GPL(pm_wakeup_dev_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_debug("active wakeup source: %s\n", ws->name);
> @@ -823,7 +825,7 @@ void pm_print_active_wakeup_sources(void
> if (!active && last_activity_ws)
> pr_debug("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);
>
> @@ -950,8 +952,9 @@ 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) {
> @@ -965,7 +968,7 @@ 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 */
>
> @@ -1026,15 +1029,16 @@ 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);
>
>
