linux-kernel - Re: [PATCH v4 07/19] irqdomain: Look for existing mapping only once

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87wn5kkfqo.ffs@tglx>
Date:   Tue, 17 Jan 2023 22:34:07 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Johan Hovold <johan+linaro@...nel.org>,
        Marc Zyngier <maz@...nel.org>
Cc:     x86@...nel.org, platform-driver-x86@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Johan Hovold <johan+linaro@...nel.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Mark-PK Tsai <mark-pk.tsai@...iatek.com>
Subject: Re: [PATCH v4 07/19] irqdomain: Look for existing mapping only once

On Mon, Jan 16 2023 at 14:50, Johan Hovold wrote:
> Avoid looking for an existing mapping twice when creating a new mapping
> using irq_create_fwspec_mapping() by factoring out the actual allocation
> which is shared with irq_create_mapping_affinity().

This changelog is incomplete and it took me a while to figure out why
this is before the race fix.

The point is that you need __irq_create_mapping_affinity() later to fix
the shared mapping race. The double check avoidance is just a nice side
effect.

So please spell it out and make it clear that this needs to be
backported too, e.g. by adding:

The split out internal function will be used to fix a shared interrupt
mapping race. This change is therefore tagged with the same fixes tag.

Fixes: ....

>  
> +static unsigned int __irq_create_mapping_affinity(struct irq_domain *domain,
> +						  irq_hw_number_t hwirq,
> +						  const struct irq_affinity_desc *affinity)

Please rename to irq_create_mapping_affinity_locked() so it's clear what
this is about and what the calling convention is. A lockdep assert to
that effect would be nice too.

Thanks,

        tglx