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From: Lukas Wunner <lukas@wunner.de>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Marc Zyngier <maz@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Bartosz Golaszewski <brgl@bgdev.pl>,
	linux-gpio@vger.kernel.org,
	Octavian Purdila <octavian.purdila@nxp.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] genirq: Deduplicate WARN_ON_ONCE() in generic_handle_domain_irq()
Date: Mon, 16 May 2022 12:04:43 +0200	[thread overview]
Message-ID: <20220516100443.GA13963@wunner.de> (raw)
In-Reply-To: <YoHvXpo8PJUDbs08@linutronix.de>

On Mon, May 16, 2022 at 08:29:50AM +0200, Sebastian Andrzej Siewior wrote:
> From looking at gpio-dln2
> this is called from USB URB's callback which is softirq. In the end
> dln2_gpio_event() is invoked while dln2_dev::event_cb_lock is acquired.
> That lock is acquired by disabling interrupts which is what gets the
> locking right for generic_handle_domain_irq(). If that lock lifted to
> spin_lock_bh() (because it is always in urb's calback context and all
> HCDs complete in one context unlike now) then this breaks.

I think you want WARN_ON(!irqs_disabled) to catch that,
not WARN_ON_ONCE(!in_hardirq()).


> and sadly I missed dln2. Please let me know if you have more users
> similar to dln2. I will add those to my list once upstream buys that
> interface.

There's another USB GPIO irqchip queued up for 5.19 now:
https://git.kernel.org/netdev/net-next/c/1ce8b37241ed

And there's one more in drivers/hid/hid-cp2112.c, but that calls
handle_nested_irq(), which disables hardirqs.

Thanks,

Lukas

      parent reply	other threads:[~2022-05-16 10:06 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-10  7:56 [PATCH] genirq: Deduplicate WARN_ON_ONCE() in generic_handle_domain_irq() Lukas Wunner
2022-05-16  6:29 ` Sebastian Andrzej Siewior
2022-05-16  6:53   ` Thomas Gleixner
2022-05-16  7:02     ` Sebastian Andrzej Siewior
2022-05-16 10:04   ` Lukas Wunner [this message]

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