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Date:   Wed, 8 Sep 2021 21:05:12 +0200
From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     Clark Williams <williams@redhat.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Steven Rostedt <rostedt@goodmis.org>,
        David Airlie <airlied@linux.ie>,
        LKML <linux-kernel@vger.kernel.org>,
        RT <linux-rt-users@vger.kernel.org>,
        Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH PREEMPT_RT] i915: fix PREEMPT_RT locking splats
Message-ID: <20210908190512.ocuyu2uzuyexas2m@linutronix.de>
References: <20210823150015.61ebc7d6@theseus>
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On 2021-08-23 15:00:15 [-0500], Clark Williams wrote:
> Found two separate spots where i915 was throwing "sleeping
> function called from invalid context" when running on a
> PREEMPT_RT kernel. In both cases it was from calling
> local_irq_disable prior to taking a spin_lock. Since spin
> locks are converted to rt_mutex_t on PREEMPT_RT this means
> that we might sleep with interrupts disabled.
> 
> Since in both cases the calls were in threaded context on RT
> (irq or ksoftirqd) and in no danger of reentrance, change the
> code to only disable interrupts on non-PREEMPT_RT kernels.
> 
> Signed-off-by: Clark Williams <williams@redhat.com>

I try to deal with this in
   https://lkml.kernel.org/r/20210908185703.2989414-1-bigeasy@linutronix.de

Sebastian