Re: [PATCH] [RFC] genirq: Check irq_data_get_irq_chip() return value before use

From: Thomas Gleixner <tglx@linutronix.de>
To: Marek Vasut <marex@denx.de>, linux-arm-kernel@lists.infradead.org
Cc: Marc Zyngier <marc.zyngier@arm.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Stephen Boyd <sboyd@codeaurora.org>,
	Alexandre Torgue <alexandre.torgue@st.com>,
	Fabien Dessenne <fabien.dessenne@st.com>
Subject: Re: [PATCH] [RFC] genirq: Check irq_data_get_irq_chip() return value before use
Date: Wed, 13 May 2020 22:49:33 +0200	[thread overview]
Message-ID: <87a72b1rxe.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <d3b76d43-675b-c699-06fa-aab448504f25@denx.de>

Marek,

Marek Vasut <marex@denx.de> writes:
> On 5/7/20 11:51 PM, Thomas Gleixner wrote:
> All right, so I found out the root cause is already fixed in next, and
> just needs to be backported to stable. I'll ping the patch author about
> that.
>
> It's this patch:
> 69269446ccbf ("mailbox: stm32-ipcc: Update wakeup management")
>
> I also need to revisit the regulator suspend topic next, that seems to
> be a separate issue after all.
>
> Sorry for the noise.

Nothing to be sorry about.

> That said, do you want to take this patch to add the missing check
> anyway or is there a reason the check is missing ?

The reason is probably that chip == NULL is unexpected at least from the
initial callers.

Adding a check for robustness is a good thing, but it should be done
slightly different.

	do {
		chip = irq_data_get_irq_chip(data);
                if (WARN_ON_ONCE(!chip))
                	return -ENODEV;

Simply because to alert the developer that this call is at the wrong
place.

Care to refresh it?

Thanks,

        tglx

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