Re: leds: avoid flush_work in atomic context

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Hi Pavel,

Thank you for the patch.

I've applied it however I'm not sure if it is an official
submission, since it doesn't look like (no [PATCH] tag
in the subject).

Beside that 'Fixes' tag is somewhat incomplete - it should be
generated using following git command:

git log -1 0db37915d912 --format='Fixes: %h ("%s")'

Fixed that and applied to the for-next branch and will push
it upstream after a bit of testing for rc3 or rc4.

Best regards,
Jacek Anaszewski

On 5/26/19 9:38 AM, Pavel Machek wrote:

It turns out that various triggers use led_blink_setup() from atomic
context, so we can't do a flush_work there. Flush is still needed for
slow LEDs, but we can move it to sysfs code where it is safe.
WARNING: inconsistent lock state
     5.2.0-rc1 #1 Tainted: G        W
     --------------------------------
     inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
     swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes:
     000000006e30541b
     ((work_completion)(&led_cdev->set_brightness_work)){+.?.}, at:
     +__flush_work+0x3b/0x38a
     {SOFTIRQ-ON-W} state was registered at:
       lock_acquire+0x146/0x1a1
      __flush_work+0x5b/0x38a
      flush_work+0xb/0xd
      led_blink_setup+0x1e/0xd3
      led_blink_set+0x3f/0x44
      tpt_trig_timer+0xdb/0x106
      ieee80211_mod_tpt_led_trig+0xed/0x112
Fixes: 0db37915d912
Signed-off-by: Pavel Machek <pavel@xxxxxx>
Tested-by: Hugh Dickins <hughd@xxxxxxxxxx>
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index aefac4d..9f8da39 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -166,11 +166,6 @@ static void led_blink_setup(struct led_classdev *led_cdev,
  		     unsigned long *delay_on,
  		     unsigned long *delay_off)
  {
-	/*
-	 * If "set brightness to 0" is pending in workqueue, we don't
-	 * want that to be reordered after blink_set()
-	 */
-	flush_work(&led_cdev->set_brightness_work);
  	if (!test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&
  	    led_cdev->blink_set &&
  	    !led_cdev->blink_set(led_cdev, delay_on, delay_off))
diff --git a/drivers/leds/trigger/ledtrig-timer.c b/drivers/leds/trigger/ledtrig-timer.c
index ca898c1..427fc3c 100644
--- a/drivers/leds/trigger/ledtrig-timer.c
+++ b/drivers/leds/trigger/ledtrig-timer.c
@@ -113,6 +113,11 @@ static int timer_trig_activate(struct led_classdev *led_cdev)
  		led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
  	}
+ /*
+	 * If "set brightness to 0" is pending in workqueue, we don't
+	 * want that to be reordered after blink_set()
+	 */
+	flush_work(&led_cdev->set_brightness_work);
  	led_blink_set(led_cdev, &led_cdev->blink_delay_on,
  		      &led_cdev->blink_delay_off);




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