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From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     Thomas Gleixner <tglx@linutronix.de>, johannes.berg@intel.com,
        linux-leds@vger.kernel.org
Subject: Re: [PATCH] leds: trigger: Disable CPU trigger on PREEMPT_RT
Message-ID: <20210927171802.uak3tbpqaig3mm7m@linutronix.de>
References: <20210924111501.m57cwwn7ahiyxxdd@linutronix.de>
 <20210927142345.GB18276@duo.ucw.cz>
 <87wnn2av6h.ffs@tglx>
 <20210927154451.GA17112@duo.ucw.cz>
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On 2021-09-27 17:44:51 [+0200], Pavel Machek wrote:
> 
> Would you mind reading and responding to the rest of the email?

The patch you mentioned,
  https://https://lkml.kernel.org/r/.kernel.org/all/20210915181601.99a68f5718be.I1a28b342d2d52cdeeeb81ecd6020c25cbf1dbfc0@changeid/

would remove the lock from led_trigger_event().
Are there any guarantees how many callbacks maybe invoked and what kind
of locks may be acquired?
Leaving kworker usage aside there are still things like spinlock_t usage
in input_leds_brightness_set(), nic78bx_brightness_set() (from a quick
grep) which have the same problems.

> I'm not applying this.

I hope you reconsider. It is not all LED usage, just the CPU trigger.

> 								Pavel

Sebastian