From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [80.241.56.172]) (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 9C3CD2E8B74; Mon, 22 Sep 2025 15:35:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758555311; cv=none; b=S7LtmA4Ov+0/FHGvTO8Mued7T2OUtE+DevLeDyPdbB4WaDXr928hz2tB3Q4pkZl+a/X4cnBhfU7S0pnVN/OzQzbH0eCfUGa7upd8a4rHu2aEcpLzYzTMsU8tPm7xDpUIHEhcK5OGSWcG5hQO9T3zHV8K3IGKTGrM+AGIagQ6nwM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758555311; c=relaxed/simple; bh=wmmR/+z+QsQGMtHaPL0yg8jT+B/kfgHKxxpjI87hzZs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ANahMbpY34q8RuP2Zi78KrF/kFqyJBviG4ht4RLqOT5/kgIQ1B/pTLdDNBU0vTF7AUz6ykpqhQ+QDaaHFisGHAuYOCxPGzBx+o5xhMmKd71hK1Oems/KwFVVbJre2+qNdqPZtBqeJxGGuG0ldZbmhfOqhjHJxKAh0jVv+c8dr+U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org; spf=pass smtp.mailfrom=mailbox.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=T7d0QJbE; arc=none smtp.client-ip=80.241.56.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mailbox.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="T7d0QJbE" Received: from smtp2.mailbox.org (smtp2.mailbox.org [IPv6:2001:67c:2050:b231:465::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-202.mailbox.org (Postfix) with ESMTPS id 4cVnH74Snyz9syv; Mon, 22 Sep 2025 17:34:59 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1758555300; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JFDDMAR85SuJgvV8n5YjG/JVQ1JyR0LrG+f32oAtf30=; b=T7d0QJbEOS09wtyCptmeP3a+4pgzxCQt+eLYJ/qSqMsAkHM2lI5osnhdGNkkk4DcwPyn4P pHo5CxIaVsziZ3cwwbacseU+vA6CZxutS/8uDbm6nlBVLYlo9d8P1FDkyGIb8S4bErAVPc fz1p0fdg+abXmB7tudc7fGIbHpQDyRfu/BaOnAXt9Hsi0fl5wSO9cNd7QfbS2QBs/ejTyV ohx1HDN7Q8hVBtMFxtx1eOZXBDvPZ/x7p8HrPBOtEzWRJEReYEPdsNipySptyxtgfB7A5Q Gc2QmhgJ3ARRBnmtIbysB3d6GsKGl/fmcbOPVj2Y2Kqcom6pBdLWmOLnlsRHGQ== Message-ID: Date: Mon, 22 Sep 2025 17:34:56 +0200 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 1/2] PCI: rcar-host: Drop PMSR spinlock To: Geert Uytterhoeven Cc: linux-pci@vger.kernel.org, Duy Nguyen , Thuan Nguyen , stable@vger.kernel.org, =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= , Bjorn Helgaas , Lorenzo Pieralisi , Magnus Damm , Manivannan Sadhasivam , Marc Zyngier , Rob Herring , Yoshihiro Shimoda , linux-renesas-soc@vger.kernel.org, Thomas Gleixner References: <20250909162707.13927-1-marek.vasut+renesas@mailbox.org> <575ae1bc-0478-4f69-9002-4a48742e04e8@mailbox.org> Content-Language: en-US From: Marek Vasut In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-MBO-RS-META: i5mtncn76bsbi9f6igbnjnbypgcrozmc X-MBO-RS-ID: c731b648d64e4b13f54 On 9/22/25 12:53 PM, Geert Uytterhoeven wrote: Hello Geert, >>> My only worry is that PCI_LOCKLESS_CONFIG may be selected on non-x86 >>> one day, breaking your assumptions. IMHO, the mechanism behind this >>> config option, introduced in commit 714fe383d6c9bd95 ("PCI: Provide >>> Kconfig option for lockless config space accessors") looks very fragile >>> to me: it is intended to be selected by an architecture, if "all" low >>> level PCI configuration space accessors use their own serialization or >>> can operate completely lockless. Usually we use the safer, inverted >>> approach (PCI_NOLOCKLESS_CONFIG), to be selected by all drivers that >>> do not adhere to the assumption. >>> But perhaps I am missing something, and this does not depend on >>> individual PCIe host drivers? >>> >>> Regardless, improving that is clearly out-of-scope for this patch... >> >> I could send a follow up patch which would add build-time assertion that >> PCI_LOCKLESS_CONFIG must not be selected for this driver to work. Would >> that be an option ? > > Or simply just "depends on !CONFIG_PCI_LOCKLESS_CONFIG"? > What do the PCIe maintainers think? I send a patch in the meantime: [PATCH] PCI: rcar-host: Add static assertion to check !PCI_LOCKLESS_CONFIG