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From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: xiujianfeng@huawei.com, kvm@vger.kernel.org,
	alvaro.karsz@solid-run.com, jasowang@redhat.com,
	angus.chen@jaguarmicro.com, wangdeming@inspur.com,
	linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
	lingshan.zhu@intel.com, linuxppc-dev@lists.ozlabs.org,
	gavinl@nvidia.com
Subject: Re: [GIT PULL] virtio: fixes, features
Date: Wed, 12 Oct 2022 10:22:08 -0700	[thread overview]
Message-ID: <CAHk-=wg2Pkb9kbfbstbB91AJA2SF6cySbsgHG-iQMq56j3VTcA@mail.gmail.com> (raw)
In-Reply-To: <20221012115023-mutt-send-email-mst@kernel.org>

On Wed, Oct 12, 2022 at 8:51 AM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> Are you sure?

MichaelE is right.

This is just bogus historical garbage:

> arch/arm/include/asm/irq.h:#ifndef NO_IRQ
> arch/arm/include/asm/irq.h:#define NO_IRQ       ((unsigned int)(-1))

that I've tried to get rid of for years, but for some reason it just won't die.

NO_IRQ should be zero. Or rather, it shouldn't exist at all. It's a bogus thing.

You can see just how bogus it is from grepping for it - the users are
all completely and utterly confused, and all are entirely historical
brokenness.

The correct way to check for "no irq" doesn't use NO_IRQ at all, it just does

        if (dev->irq) ...

which is why you will only find a few instances of NO_IRQ in the tree
in the first place.

The NO_IRQ thing is mainly actually defined by a few drivers that just
never got converted to the proper world order, and even then you can
see the confusion (ie some drivers use "-1", others use "0", and yet
others use "((unsigned int)(-1)".

                   Linus

  reply	other threads:[~2022-10-12 17:23 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20221010132030-mutt-send-email-mst@kernel.org>
2022-10-12  6:21 ` [GIT PULL] virtio: fixes, features Michael Ellerman
2022-10-12  6:45   ` Angus Chen
2022-10-12  7:35   ` Angus Chen
2022-10-12 11:11   ` Michael S. Tsirkin
2022-10-12 13:28     ` Michael Ellerman
2022-10-12 14:33       ` Michael Ellerman
2022-10-12 15:51         ` Michael S. Tsirkin
2022-10-12 17:22           ` Linus Torvalds [this message]
2022-10-12 21:06             ` Arnd Bergmann
2022-10-12 22:08               ` Michael S. Tsirkin
2022-10-13  6:28                 ` Arnd Bergmann
2022-10-13 17:19                   ` Linus Torvalds

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