From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 257FAC001DD for ; Thu, 13 Jul 2023 17:04:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230093AbjGMRD7 (ORCPT ); Thu, 13 Jul 2023 13:03:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38828 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229980AbjGMRD6 (ORCPT ); Thu, 13 Jul 2023 13:03:58 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F6B52700; Thu, 13 Jul 2023 10:03:58 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A6E6D61AED; Thu, 13 Jul 2023 17:03:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C2C31C433C8; Thu, 13 Jul 2023 17:03:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689267837; bh=+qeyXsRrQ/U2yh6VTcdgE7vMtiDddsPP8kKRqmBbsC4=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=ldRUBCz1IijQ2TRJznDuOdfdNLVlCgTn8OwirEAkjEQzdy1+SVvxmVgg9yF8qf3RA GSXMDzrmc6CeMhEJsIwtEMxbWUjWfbKynBYzA6xfO57OQya8HgKi6EL4OOnMmdz6gG SExAd79qm0KKzjb/zY0GM2xLCz/VUcQXe8f6RJzA1Njuk13+5tUeQGunZGFFlAe2Px RxjqZMvof3cZguglyIFIalImEJlJsBQts9MCTAkLboqfs9rDNy0hcNgm3Eiilqd+pk PK71+MiET4cGnHEmQN8mC7+H1Soki7SRRL+GnMBzzs0j1+4FqW0LJBGIqygWYCmfYm ARAT3V8JMvRTA== Date: Thu, 13 Jul 2023 12:03:55 -0500 From: Bjorn Helgaas To: Radu Rendec Cc: Jingoo Han , Gustavo Pimentel , Lorenzo Pieralisi , Krzysztof Wilczynski , Rob Herring , Bjorn Helgaas , Marc Zyngier , Thomas Gleixner , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Pali =?iso-8859-1?Q?Roh=E1r?= Subject: Re: [PATCH 1/1] PCI: dwc: Use regular interrupt instead of chained Message-ID: <20230713170355.GA323073@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <8715f2b298c04422db311666eb2409464c29458b.camel@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Jun 29, 2023 at 11:04:50PM -0400, Radu Rendec wrote: > On Thu, 2023-06-29 at 17:11 -0500, Bjorn Helgaas wrote: > ... > > If converting from chained to normal handlers can be done safely, I > > would definitely be in favor if doing it across all of drivers/pci/ at > > once so they're all consistent.  Otherwise that code just gets copied > > to new drivers, so the issue persists and spreads. > > I think the conversion can be done safely, meaning that it won't break > the drivers. And by the way, there are other IRQ drivers (outside the > PCI space) that use chained interrupts. > > Unfortunately, it seems we are going in circles. Chained interrupts are > bad because they let IRQ storms go unnoticed and lock up the system, > but converting them to regular interrupts is also bad because it breaks > the userspace ABI. > > I am willing to help clean up this mess, but I think first we need to > come up with a solution that's acceptable for everybody. I was hoping > Marc and Thomas would chime in, but unfortunately that hasn't happened > yet - other than each of them pointing out (separately) what is wrong > with each approach. I don't think Marc or Thomas are going to chime in with a fully-formed solution. I think to make progress, you (or Pali, or somebody) will have to try to address Marc and Thomas' comments, make a proposal, and we can iterate on it. Bjorn