From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Aman Sharma <amanharitsh123@gmail.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH v2 1/2] driver core: platform: Clarify that IRQ 0 is invalid
Date: Sat, 2 May 2020 08:15:37 +0200 [thread overview]
Message-ID: <20200502061537.GA2527384@kroah.com> (raw)
In-Reply-To: <20200501224042.141366-2-helgaas@kernel.org>
On Fri, May 01, 2020 at 05:40:41PM -0500, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@google.com>
>
> These interfaces return a negative error number or an IRQ:
>
> platform_get_irq()
> platform_get_irq_optional()
> platform_get_irq_byname()
> platform_get_irq_byname_optional()
>
> The function comments suggest checking for error like this:
>
> irq = platform_get_irq(...);
> if (irq < 0)
> return irq;
>
> which is what most callers (~900 of 1400) do, so it's implicit that IRQ 0
> is invalid. But some callers check for "irq <= 0", and it's not obvious
> from the source that we never return an IRQ 0.
>
> Make this more explicit by updating the comments to say that an IRQ number
> is always non-zero and adding a WARN() if we ever do return zero. If we do
> return IRQ 0, it likely indicates a bug in the arch-specific parts of
> platform_get_irq().
I worry about adding WARN() as there are systems that do panic_on_warn()
and syzbot trips over this as well. I don't think that for this issue
it would be a problem, but what really is this warning about that
someone could do anything with?
Other than that minor thing, this looks good to me, thanks for finally
clearing this up.
greg k-h
next prev parent reply other threads:[~2020-05-02 6:15 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-01 22:40 [PATCH v2 0/2] PCI: Check for platform_get_irq() failure consistently Bjorn Helgaas
2020-05-01 22:40 ` [PATCH v2 1/2] driver core: platform: Clarify that IRQ 0 is invalid Bjorn Helgaas
2020-05-02 6:15 ` Greg Kroah-Hartman [this message]
2020-05-04 18:08 ` Bjorn Helgaas
2020-05-04 19:07 ` Greg Kroah-Hartman
2020-05-04 22:26 ` Bjorn Helgaas
2020-05-05 13:35 ` Greg Kroah-Hartman
2020-05-01 22:40 ` [PATCH v2 2/2] PCI: Check for platform_get_irq() failure consistently Bjorn Helgaas
2020-05-12 12:35 ` [PATCH v2 0/2] " Linus Walleij
2020-05-13 17:44 ` Bjorn Helgaas
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