From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Brian Silverman <brian@peloton-tech.com>
Cc: rt-users <linux-rt-users@vger.kernel.org>
Subject: Re: problems with chained IRQ handlers
Date: Fri, 11 Dec 2015 17:23:46 +0100 [thread overview]
Message-ID: <20151211162346.GC6720@linutronix.de> (raw)
In-Reply-To: <CAGt3f4k=-TW2qVhqMFk7U22NGZToZ5bxi1qVuUqcVRKqjhBbMw@mail.gmail.com>
* Brian Silverman | 2015-08-17 18:41:55 [-0700]:
>Chained IRQ handlers are always marked IRQ_NOTHREAD, which means
>forced threading doesn't apply to them. I think this means they can't
>safely use non-raw spinlocks under CONFIG_PREEMPT_RT_FULL. Is this
>correct?
yes,
>I have an ARM system with a CONFIG_PREEMPT_RT_FULL kernel which prints
>lockdep warnings from many places because of this. It also locks up
>under moderate load, which I think is related to this issue. Any
>suggestions?
Use raw locks there. The chain handler usually implement a irq chip
something like gpio controller which can also act as an interrupt
controller. If this is the case then the lock should be a raw-lock.
You should not do anything time consuming while holding the lock. It is
usually just held while masking/unmasking bits in the registers.
>Thanks,
>Brian Silverman
Sebastia
prev parent reply other threads:[~2015-12-11 16:23 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-18 1:41 problems with chained IRQ handlers Brian Silverman
2015-12-11 16:23 ` Sebastian Andrzej Siewior [this message]
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