From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DAB6E25C6EE for ; Mon, 10 Feb 2025 20:08:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739218137; cv=none; b=GXCznI8lPXLNUKjDtAnJLbpSwSBrnQq70/Z25BT6cUWisc0S91i/QqzKaj7KmoFf9A2uiOZoPEdMJnZOgifkDA090JZ39/Svjh/PCE794c5bVX4yp5KjnZm5wzSBfyqFKThCyX5ZEwNgg1c6aLtKRkitoWtAdQkWoC29cpL9D2g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739218137; c=relaxed/simple; bh=yBbYMBadCXT0kaevdazzwYvBDUOb8j9NDpwULSbXHAs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VgEEPrcQNJPWK8hIYG70jm+hxxYzn56SddghlgZ0tjAkvGtUnmPDJCBibwj/2UyyE7EfLBmJEpWZAPpmCOMT5gyPFRce7mbCom/M4eub3OA0v8Rl8CQ3xqqYcxvtKYU8JnESbWAl4ulFpQIVD8UP5yEfOUFRPVSd+WvzSjQTOaw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=A9XaiGCH; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="A9XaiGCH" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739218134; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=33qRbDaL39Ei5gBDRIf8L9n5D2Vc2pGydYaJ7tW4WTc=; b=A9XaiGCHfL2hqye1VVLFN2rRTpFD6/zRR0os330B548Q0adC+MRTYG4m/qXm6bMssRAHd/ /UaWELnXlrK/OtGnBIopKZ4q3t5UB+kNxtXikDCPBdOogiMejOhOpu7Y58nMGprHGs2ao6 fZqaB0oBXMqJ7Vg0LysYekFEbHDzn7Q= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-663-eO4fuNYsO_Orgdd-QdYTEA-1; Mon, 10 Feb 2025 15:08:51 -0500 X-MC-Unique: eO4fuNYsO_Orgdd-QdYTEA-1 X-Mimecast-MFC-AGG-ID: eO4fuNYsO_Orgdd-QdYTEA Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3ADF718004A7; Mon, 10 Feb 2025 20:08:50 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.113]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id A6FC630001AB; Mon, 10 Feb 2025 20:08:47 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 10 Feb 2025 21:08:23 +0100 (CET) Date: Mon, 10 Feb 2025 21:08:19 +0100 From: Oleg Nesterov To: Alex Williamson Cc: bhelgaas@google.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, mitchell.augustin@canonical.com, ilpo.jarvinen@linux.intel.com Subject: Re: [PATCH v2] PCI: Batch BAR sizing operations Message-ID: <20250210200819.GL32480@redhat.com> References: <20250120182202.1878581-1-alex.williamson@redhat.com> <20250209154512.GA18688@redhat.com> <20250210093641.0be242ae.alex.williamson@redhat.com> <20250210195658.GK32480@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250210195658.GK32480@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On 02/10, Oleg Nesterov wrote: > > On 02/10, Alex Williamson wrote: > > > > --- a/drivers/pci/probe.c > > +++ b/drivers/pci/probe.c > > @@ -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); > > + if (__builtin_constant_p(howmany)) > > + BUILD_BUG_ON(howmany > PCI_STD_NUM_BARS); > > Or just > > BUILD_BUG_ON(__builtin_constant_p(howmany) && howmany > PCI_STD_NUM_BARS); > > I dunno... Works for me in any case. > > I don't know if this is "right" solution though, I mean, atm I simply don't know if with the newer compiler __builtin_constant_p(howmany) will be true in this case. Oleg.