linux-kernel - Re: [PATCH] PCI: Fix BUILD_BUG

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Message-ID: <20250211100502.GA9174@redhat.com>
Date: Tue, 11 Feb 2025 11:05:03 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Alex Williamson <alex.williamson@...hat.com>
Cc: bhelgaas@...gle.com, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, mitchell.augustin@...onical.com,
	ilpo.jarvinen@...ux.intel.com,
	David Laight <david.laight.linux@...il.com>
Subject: Re: [PATCH] PCI: Fix BUILD_BUG_ON usage for old gcc

On 02/10, Oleg Nesterov wrote:
>
> On 02/10, Alex Williamson wrote:
> >
> > @@ -345,7 +345,8 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
> >  	unsigned int pos, reg;
> >  	u16 orig_cmd;
> >
> > -	BUILD_BUG_ON(howmany > PCI_STD_NUM_BARS);
> > +	BUILD_BUG_ON(__builtin_constant_p(howmany) &&
> > +		     howmany > PCI_STD_NUM_BARS);
>
> Thanks!
>
> Tested-by: Oleg Nesterov <oleg@...hat.com>

Just in case... I agree with David, statically_true() looks a bit
better and

	BUILD_BUG_ON(statically_true(howmany > PCI_STD_NUM_BARS));

also works for me, so if you decide to update this patch feel free
to keep my Tested-by.

Oleg.