linux-kernel - Re: [PATCH] x86/ioapic: Don't return 0 as valid virq

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Message-ID: <20230312204019.GBZA44s28AOAfAcRuy@fat_crate.local>
Date:   Sun, 12 Mar 2023 21:40:19 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Saurabh Sengar <ssengar@...ux.microsoft.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, johan+linaro@...nel.org,
        isaku.yamahata@...el.com, mikelley@...rosoft.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/ioapic: Don't return 0 as valid virq

On Thu, Mar 02, 2023 at 11:34:46AM -0800, Saurabh Sengar wrote:
> Zero is invalid virq and should't be returned as a valid value for
> lower irq bound. If IO-APIC and gsi_top are not initialized return

Why isn't gsi_top initialized?

What is this fixing?

Don't be afraid to do

git annotate arch/x86/kernel/apic/io_apic.c

and see which commit added this. This one:

3e5bedc2c258 ("x86/apic: Fix arch_dynirq_lower_bound() bug for DT enabled machines")

Now add the folks from this commit to Cc and tell them why in your case
gsi_top is not initialized and what they're breaking by doing that.

The more your commit message explains *why* you're fixing something, the
better it is for the maintainers/reviewers to actually know what to do.

Right now I'm reading this and I'm thinking, random, unjustified change.
Ignore.

Ok?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette