Fix oops about sleeping in led_trigger_blink()

led_blink_set[_oneshot]()'s delay_on and delay_off function parameters are pass by reference, so that hw-blink implementations can report back the actual achieved delays when the values have been rounded to something the hw supports.

This is really only interesting for the sysfs API / the timer trigger. Other triggers don't really care about this and none of the callers of led_trigger_blink[_oneshot]() do anything with the returned delay values.

Change the led_trigger_blink[_oneshot]() delay parameters to pass-by-value, there are 2 reasons for this:

1. led_cdev->blink_set() may sleep, while led_trigger_blink() may not. So on hw where led_cdev->blink_set() sleeps the call needs to be deferred to a workqueue, in which case the actual achieved delays are unknown (this is a preparation patch for the deferring).

2. Since the callers don't care about the actual achieved delays, allowing callers to directly pass a value leads to simpler code for most callers.

Reviewed-by Jacek Anaszewski <[email protected]>

Tested-by Yauhen Kharuzhy <[email protected]>

Signed-off-by Hans de Goede <[email protected]>

---
 drivers/leds/led-triggers.c              | 16 ++++++++--------
 drivers/leds/trigger/ledtrig-disk.c      |  9 +++------
 drivers/leds/trigger/ledtrig-mtd.c       |  8 ++------
 drivers/net/arcnet/arcnet.c              |  8 ++------
 drivers/power/supply/power_supply_leds.c |  5 +----
 drivers/usb/common/led.c                 |  4 +---
 include/linux/leds.h                     | 16 ++++++++--------
 net/mac80211/led.c                       |  2 +-
 net/mac80211/led.h                       |  8 ++------
 net/netfilter/xt_LED.c                   |  3 +--
 10 files changed, 29 insertions(+), 50 deletions(-)

drivers/leds/led-triggers.c +8 -8

index 072491d3e17b..e06361165e9b 100644
@@ -393,8 +393,8 @@ void led_trigger_event(struct led_trigger *trig,
 EXPORT_SYMBOL_GPL(led_trigger_event);
 
 static void led_trigger_blink_setup(struct led_trigger *trig,
-			     unsigned long *delay_on,
-			     unsigned long *delay_off,
+			     unsigned long delay_on,
+			     unsigned long delay_off,
 			     int oneshot,
 			     int invert)
 {

@@ -406,25 +406,25 @@ static void led_trigger_blink_setup(struct led_trigger *trig,
 	rcu_read_lock();
 	list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
 		if (oneshot)
-			led_blink_set_oneshot(led_cdev, delay_on, delay_off,
+			led_blink_set_oneshot(led_cdev, &delay_on, &delay_off,
 					      invert);
 		else
-			led_blink_set(led_cdev, delay_on, delay_off);
+			led_blink_set(led_cdev, &delay_on, &delay_off);
 	}
 	rcu_read_unlock();
 }
 
 void led_trigger_blink(struct led_trigger *trig,
-		       unsigned long *delay_on,
-		       unsigned long *delay_off)
+		       unsigned long delay_on,
+		       unsigned long delay_off)
 {
 	led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 }
 EXPORT_SYMBOL_GPL(led_trigger_blink);
 
 void led_trigger_blink_oneshot(struct led_trigger *trig,
-			       unsigned long *delay_on,
-			       unsigned long *delay_off,
+			       unsigned long delay_on,
+			       unsigned long delay_off,
 			       int invert)
 {
 	led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);

drivers/leds/trigger/ledtrig-disk.c +3 -6

index 0b7dfbd04273..e9b87ee944f2 100644
@@ -19,16 +19,13 @@ DEFINE_LED_TRIGGER(ledtrig_disk_write);
 
 void ledtrig_disk_activity(bool write)
 {
-	unsigned long blink_delay = BLINK_DELAY;
-
-	led_trigger_blink_oneshot(ledtrig_disk,
-				  &blink_delay, &blink_delay, 0);
+	led_trigger_blink_oneshot(ledtrig_disk, BLINK_DELAY, BLINK_DELAY, 0);
 	if (write)
 		led_trigger_blink_oneshot(ledtrig_disk_write,
-					  &blink_delay, &blink_delay, 0);
+					  BLINK_DELAY, BLINK_DELAY, 0);
 	else
 		led_trigger_blink_oneshot(ledtrig_disk_read,
-					  &blink_delay, &blink_delay, 0);
+					  BLINK_DELAY, BLINK_DELAY, 0);
 }
 EXPORT_SYMBOL(ledtrig_disk_activity);
 

drivers/leds/trigger/ledtrig-mtd.c +2 -6

index 8fa763c2269b..bbe6876a249d 100644
@@ -22,12 +22,8 @@ DEFINE_LED_TRIGGER(ledtrig_nand);
 
 void ledtrig_mtd_activity(void)
 {
-	unsigned long blink_delay = BLINK_DELAY;
-
-	led_trigger_blink_oneshot(ledtrig_mtd,
-				  &blink_delay, &blink_delay, 0);
-	led_trigger_blink_oneshot(ledtrig_nand,
-				  &blink_delay, &blink_delay, 0);
+	led_trigger_blink_oneshot(ledtrig_mtd, BLINK_DELAY, BLINK_DELAY, 0);
+	led_trigger_blink_oneshot(ledtrig_nand, BLINK_DELAY, BLINK_DELAY, 0);
 }
 EXPORT_SYMBOL(ledtrig_mtd_activity);
 

drivers/net/arcnet/arcnet.c +2 -6

index 1bad1866ae46..99265667538c 100644
@@ -196,13 +196,10 @@ static void arcnet_dump_packet(struct net_device *dev, int bufnum,
 void arcnet_led_event(struct net_device *dev, enum arcnet_led_event event)
 {
 	struct arcnet_local *lp = netdev_priv(dev);
-	unsigned long led_delay = 350;
-	unsigned long tx_delay = 50;
 
 	switch (event) {
 	case ARCNET_LED_EVENT_RECON:
-		led_trigger_blink_oneshot(lp->recon_led_trig,
-					  &led_delay, &led_delay, 0);
+		led_trigger_blink_oneshot(lp->recon_led_trig, 350, 350, 0);
 		break;
 	case ARCNET_LED_EVENT_OPEN:
 		led_trigger_event(lp->tx_led_trig, LED_OFF);

@@ -213,8 +210,7 @@ void arcnet_led_event(struct net_device *dev, enum arcnet_led_event event)
 		led_trigger_event(lp->recon_led_trig, LED_OFF);
 		break;
 	case ARCNET_LED_EVENT_TX:
-		led_trigger_blink_oneshot(lp->tx_led_trig,
-					  &tx_delay, &tx_delay, 0);
+		led_trigger_blink_oneshot(lp->tx_led_trig, 50, 50, 0);
 		break;
 	}
 }

drivers/power/supply/power_supply_leds.c +1 -4

index 702bf83f6e6d..e2f554e4e4e6 100644
@@ -22,8 +22,6 @@
 static void power_supply_update_bat_leds(struct power_supply *psy)
 {
 	union power_supply_propval status;
-	unsigned long delay_on = 0;
-	unsigned long delay_off = 0;
 
 	if (power_supply_get_property(psy, POWER_SUPPLY_PROP_STATUS, &status))
 		return;

@@ -42,8 +40,7 @@ static void power_supply_update_bat_leds(struct power_supply *psy)
 		led_trigger_event(psy->charging_full_trig, LED_FULL);
 		led_trigger_event(psy->charging_trig, LED_FULL);
 		led_trigger_event(psy->full_trig, LED_OFF);
-		led_trigger_blink(psy->charging_blink_full_solid_trig,
-			&delay_on, &delay_off);
+		led_trigger_blink(psy->charging_blink_full_solid_trig, 0, 0);
 		break;
 	default:
 		led_trigger_event(psy->charging_full_trig, LED_OFF);

drivers/usb/common/led.c +1 -3

index 0865dd44a80a..1de18d90b134 100644
@@ -14,8 +14,6 @@
 
 #define BLINK_DELAY 30
 
-static unsigned long usb_blink_delay = BLINK_DELAY;
-
 DEFINE_LED_TRIGGER(ledtrig_usb_gadget);
 DEFINE_LED_TRIGGER(ledtrig_usb_host);
 

@@ -32,7 +30,7 @@ void usb_led_activity(enum usb_led_event ev)
 		break;
 	}
 	/* led_trigger_blink_oneshot() handles trig == NULL gracefully */
-	led_trigger_blink_oneshot(trig, &usb_blink_delay, &usb_blink_delay, 0);
+	led_trigger_blink_oneshot(trig, BLINK_DELAY, BLINK_DELAY, 0);
 }
 EXPORT_SYMBOL_GPL(usb_led_activity);
 

include/linux/leds.h +8 -8

index c39bbf17a25b..c3dc22d184e2 100644
@@ -433,11 +433,11 @@ void led_trigger_register_simple(const char *name,
 				struct led_trigger **trigger);
 void led_trigger_unregister_simple(struct led_trigger *trigger);
 void led_trigger_event(struct led_trigger *trigger,  enum led_brightness event);
-void led_trigger_blink(struct led_trigger *trigger, unsigned long *delay_on,
-		       unsigned long *delay_off);
+void led_trigger_blink(struct led_trigger *trigger, unsigned long delay_on,
+		       unsigned long delay_off);
 void led_trigger_blink_oneshot(struct led_trigger *trigger,
-			       unsigned long *delay_on,
-			       unsigned long *delay_off,
+			       unsigned long delay_on,
+			       unsigned long delay_off,
 			       int invert);
 void led_trigger_set_default(struct led_classdev *led_cdev);
 int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger);

@@ -487,11 +487,11 @@ static inline void led_trigger_unregister_simple(struct led_trigger *trigger) {}
 static inline void led_trigger_event(struct led_trigger *trigger,
 				enum led_brightness event) {}
 static inline void led_trigger_blink(struct led_trigger *trigger,
-				      unsigned long *delay_on,
-				      unsigned long *delay_off) {}
+				      unsigned long delay_on,
+				      unsigned long delay_off) {}
 static inline void led_trigger_blink_oneshot(struct led_trigger *trigger,
-				      unsigned long *delay_on,
-				      unsigned long *delay_off,
+				      unsigned long delay_on,
+				      unsigned long delay_off,
 				      int invert) {}
 static inline void led_trigger_set_default(struct led_classdev *led_cdev) {}
 static inline int led_trigger_set(struct led_classdev *led_cdev,

net/mac80211/led.c +1 -1

index 6de8d0ad5497..2dc732147e85 100644
@@ -282,7 +282,7 @@ static void tpt_trig_timer(struct timer_list *t)
 		}
 	}
 
-	led_trigger_blink(&local->tpt_led, &on, &off);
+	led_trigger_blink(&local->tpt_led, on, off);
 }
 
 const char *

net/mac80211/led.h +2 -6

index b71a1428d883..d25f13346b82 100644
@@ -13,22 +13,18 @@
 static inline void ieee80211_led_rx(struct ieee80211_local *local)
 {
 #ifdef CONFIG_MAC80211_LEDS
-	unsigned long led_delay = MAC80211_BLINK_DELAY;
-
 	if (!atomic_read(&local->rx_led_active))
 		return;
-	led_trigger_blink_oneshot(&local->rx_led, &led_delay, &led_delay, 0);
+	led_trigger_blink_oneshot(&local->rx_led, MAC80211_BLINK_DELAY, MAC80211_BLINK_DELAY, 0);
 #endif
 }
 
 static inline void ieee80211_led_tx(struct ieee80211_local *local)
 {
 #ifdef CONFIG_MAC80211_LEDS
-	unsigned long led_delay = MAC80211_BLINK_DELAY;
-
 	if (!atomic_read(&local->tx_led_active))
 		return;
-	led_trigger_blink_oneshot(&local->tx_led, &led_delay, &led_delay, 0);
+	led_trigger_blink_oneshot(&local->tx_led, MAC80211_BLINK_DELAY, MAC80211_BLINK_DELAY, 0);
 #endif
 }
 

net/netfilter/xt_LED.c +1 -2

index 66b0f941d8fb..36c9720ad8d6 100644
@@ -43,7 +43,6 @@ led_tg(struct sk_buff *skb, const struct xt_action_param *par)
 {
 	const struct xt_led_info *ledinfo = par->targinfo;
 	struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
-	unsigned long led_delay = XT_LED_BLINK_DELAY;
 
 	/*
 	 * If "always blink" is enabled, and there's still some time until the

@@ -52,7 +51,7 @@ led_tg(struct sk_buff *skb, const struct xt_action_param *par)
 	if ((ledinfo->delay > 0) && ledinfo->always_blink &&
 	    timer_pending(&ledinternal->timer))
 		led_trigger_blink_oneshot(&ledinternal->netfilter_led_trigger,
-					  &led_delay, &led_delay, 1);
+					  XT_LED_BLINK_DELAY, XT_LED_BLINK_DELAY, 1);
 	else
 		led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL);
 

Signature · 1 line

2.40.1

led_blink_set[_oneshot]()'s delay_on and delay_off function parameters are pass by reference, so that hw-blink implementations can report back the actual achieved delays when the values have been rounded to something the hw supports.

This is really only interesting for the sysfs API / the timer trigger. Other triggers don't really care about this and none of the callers of led_trigger_blink[_oneshot]() do anything with the returned delay values.

Change the led_trigger_blink[_oneshot]() delay parameters to pass-by-value, there are 2 reasons for this:

1. led_cdev->blink_set() may sleep, while led_trigger_blink() may not. So on hw where led_cdev->blink_set() sleeps the call needs to be deferred to a workqueue, in which case the actual achieved delays are unknown (this is a preparation patch for the deferring).

2. Since the callers don't care about the actual achieved delays, allowing callers to directly pass a value leads to simpler code for most callers.

led_blink_set[_oneshot]()'s delay_on and delay_off function parameters are pass by reference, so that hw-blink implementations can report back the actual achieved delays when the values have been rounded to something the hw supports.

This is really only interesting for the sysfs API / the timer trigger. Other triggers don't really care about this and none of the callers of led_trigger_blink[_oneshot]() do anything with the returned delay values.

Change the led_trigger_blink[_oneshot]() delay parameters to pass-by-value, there are 2 reasons for this:

1. led_cdev->blink_set() may sleep, while led_trigger_blink() may not. So on hw where led_cdev->blink_set() sleeps the call needs to be deferred to a workqueue, in which case the actual achieved delays are unknown (this is a preparation patch for the deferring).

2. Since the callers don't care about the actual achieved delays, allowing callers to directly pass a value leads to simpler code for most callers.

Reviewed-by Jacek Anaszewski <[email protected]>

Tested-by Yauhen Kharuzhy <[email protected]>

Signed-off-by Hans de Goede <[email protected]>

led_blink_set[_oneshot]()'s delay_on and delay_off function parameters are pass by reference, so that hw-blink implementations can report back the actual achieved delays when the values have been rounded to something the hw supports.

This is really only interesting for the sysfs API / the timer trigger. Other triggers don't really care about this and none of the callers of led_trigger_blink[_oneshot]() do anything with the returned delay values.

Change the led_trigger_blink[_oneshot]() delay parameters to pass-by-value, there are 2 reasons for this:

1. led_cdev->blink_set() may sleep, while led_trigger_blink() may not. So on hw where led_cdev->blink_set() sleeps the call needs to be deferred to a workqueue, in which case the actual achieved delays are unknown (this is a preparation patch for the deferring).

2. Since the callers don't care about the actual achieved delays, allowing callers to directly pass a value leads to simpler code for most callers.

Reviewed-by Jacek Anaszewski <[email protected]>

Tested-by Yauhen Kharuzhy <[email protected]>

Signed-off-by Hans de Goede <[email protected]>

---
 drivers/leds/led-triggers.c              | 16 ++++++++--------
 drivers/leds/trigger/ledtrig-disk.c      |  9 +++------
 drivers/leds/trigger/ledtrig-mtd.c       |  8 ++------
 drivers/net/arcnet/arcnet.c              |  8 ++------
 drivers/power/supply/power_supply_leds.c |  5 +----
 drivers/usb/common/led.c                 |  4 +---
 include/linux/leds.h                     | 16 ++++++++--------
 net/mac80211/led.c                       |  2 +-
 net/mac80211/led.h                       |  8 ++------
 net/netfilter/xt_LED.c                   |  3 +--
 10 files changed, 29 insertions(+), 50 deletions(-)

When a trigger wants to switch from blinking to LED on it needs to call:

	led_set_brightness(LED_OFF);
	led_set_brightness(LED_FULL);

To first call disables blinking and the second then turns the LED on (the power-supply charging-blink-full-solid triggers do this).

These calls happen immediately after each other, so it is possible that set_brightness_delayed() from the first call has not run yet when the led_set_brightness(LED_FULL) call finishes.

If this race hits then this is causing problems for both sw- and hw-blinking:

For sw-blinking set_brightness_delayed() clears delayed_set_value when LED_BLINK_DISABLE is set causing the led_set_brightness(LED_FULL) call effects to get lost when hitting the race, resulting in the LED turning off instead of on.

For hw-blinking if the race hits delayed_set_value has been set to LED_FULL by the time set_brightness_delayed() runs. So led_cdev->brightness_set_blocking() is never called with LED_OFF as argument and the hw-blinking is never disabled leaving the LED blinking instead of on.

Fix both issues by adding LED_SET_BRIGHTNESS and LED_SET_BRIGHTNESS_OFF work_flags making this 2 separate actions to be run by set_brightness_delayed().

Reviewed-by Jacek Anaszewski <[email protected]>

Tested-by Yauhen Kharuzhy <[email protected]>

Signed-off-by Hans de Goede <[email protected]>

---
 drivers/leds/led-core.c | 57 +++++++++++++++++++++++++++++++----------
 include/linux/leds.h    |  3 +++
 2 files changed, 47 insertions(+), 13 deletions(-)

led_trigger_blink() calls led_blink_set() from a RCU read-side critical section so led_blink_set() must not sleep. Note sleeping was not allowed before the switch to RCU either because a spinlock was held before.

led_blink_set() does not sleep when sw-blinking is used, but many LED controller drivers with hw blink support have a blink_set function which may sleep, leading to an oops like this one:

[  832.605062] ------------[ cut here ]------------
[  832.605085] Voluntary context switch within RCU read-side critical section!
[  832.605119] WARNING: CPU: 2 PID: 370 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x4ee/0x690
<snip>
[  832.606453] Call Trace:
[  832.606466]  <TASK>
[  832.606487]  __schedule+0x9f/0x1480
[  832.606527]  schedule+0x5d/0xe0
[  832.606549]  schedule_timeout+0x79/0x140
[  832.606572]  ? __pfx_process_timeout+0x10/0x10
[  832.606599]  wait_for_completion_timeout+0x6f/0x140
[  832.606627]  i2c_dw_xfer+0x101/0x460
[  832.606659]  ? psi_group_change+0x168/0x400
[  832.606680]  __i2c_transfer+0x172/0x6d0
[  832.606709]  i2c_smbus_xfer_emulated+0x27d/0x9c0
[  832.606732]  ? __schedule+0x430/0x1480
[  832.606753]  ? preempt_count_add+0x6a/0xa0
[  832.606778]  ? get_nohz_timer_target+0x18/0x190
[  832.606796]  ? lock_timer_base+0x61/0x80
[  832.606817]  ? preempt_count_add+0x6a/0xa0
[  832.606842]  __i2c_smbus_xfer+0xa2/0x3f0
[  832.606862]  i2c_smbus_xfer+0x66/0xf0
[  832.606882]  i2c_smbus_read_byte_data+0x41/0x70
[  832.606901]  ? _raw_spin_unlock_irqrestore+0x23/0x40
[  832.606922]  ? __pm_runtime_suspend+0x46/0xc0
[  832.606946]  cht_wc_byte_reg_read+0x2e/0x60
[  832.606972]  _regmap_read+0x5c/0x120
[  832.606997]  _regmap_update_bits+0x96/0xc0
[  832.607023]  regmap_update_bits_base+0x5b/0x90
[  832.607053]  cht_wc_leds_brightness_get+0x412/0x910 [leds_cht_wcove]
[  832.607094]  led_blink_setup+0x28/0x100
[  832.607119]  led_trigger_blink+0x40/0x70
[  832.607145]  power_supply_update_leds+0x1b7/0x1c0
[  832.607174]  power_supply_changed_work+0x67/0xe0
[  832.607198]  process_one_work+0x1c8/0x3c0
[  832.607222]  worker_thread+0x4d/0x380
[  832.607243]  ? __pfx_worker_thread+0x10/0x10
[  832.607258]  kthread+0xe9/0x110
[  832.607279]  ? __pfx_kthread+0x10/0x10
[  832.607300]  ret_from_fork+0x2c/0x50
[  832.607337]  </TASK>
[  832.607344] ---[ end trace 0000000000000000 ]---

Add a new led_blink_set_nosleep() function which defers the actual led_blink_set() call to a workqueue when necessary to fix this.

This also fixes an existing race where a pending led_set_brightness() has been deferred to set_brightness_work and might then race with a later led_cdev->blink_set() call. Note this race is only an issue with triggers mixing led_trigger_event() and led_trigger_blink() calls, sysfs API calls and led_trigger_blink_oneshot() are not affected.

Note rather then adding a separate blink_set_blocking callback this uses the presence of the already existing brightness_set_blocking callback to detect if the blinking call should be deferred to set_brightness_work.

Reviewed-by Jacek Anaszewski <[email protected]>

Tested-by Yauhen Kharuzhy <[email protected]>

Signed-off-by Hans de Goede <[email protected]>

---
 drivers/leds/led-core.c     | 24 ++++++++++++++++++++++++
 drivers/leds/led-triggers.c |  2 +-
 include/linux/leds.h        | 24 ++++++++++++++++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)

Not all triggers use LED_INIT_DEFAULT_TRIGGER, which means that it will not get cleared when the default trigger is a trigger which does not use it such as "default-on".

If the default trigger then later gets replaced by a trigger which does check LED_INIT_DEFAULT_TRIGGER, such as "timer" then that trigger will behave as if it is the default trigger which it should not do.

To fix this clear the LED_INIT_DEFAULT_TRIGGER flag when clearing the current trigger, so that it will not be set for any subsequently set (non default) triggers.

Reviewed-by Jacek Anaszewski <[email protected]>

Tested-by Yauhen Kharuzhy <[email protected]>

Signed-off-by Hans de Goede <[email protected]>

---
 drivers/leds/led-triggers.c | 1 +
 1 file changed, 1 insertion(+)