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 97C86C54EAA for ; Tue, 24 Jan 2023 15:06:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234601AbjAXPGF (ORCPT ); Tue, 24 Jan 2023 10:06:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231827AbjAXPGD (ORCPT ); Tue, 24 Jan 2023 10:06:03 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6841457F6; Tue, 24 Jan 2023 07:06:02 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 606D0B811EC; Tue, 24 Jan 2023 15:06:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1FE6C433D2; Tue, 24 Jan 2023 15:05:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1674572760; bh=3OD487aODCZ8O2PP1vtAxHlZb/3WM0trzdY3u9yrrG8=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=J/oLt1358Tizyc8ehlgoxAYw1Hf+6RJ71EBM+epLVN87LT32xPep1Tb6KSbRi/dma 3nlgeyz7AQujCyC9es/yXgmeDoZ5s6sfKWGe+L0s+5zINCv9qssin5qyRf9Y1n+OFE 20VkXvCCFwRkf7ySFZuUbyT+didImwO/cz0pwHwWTxyJvEGFZ1OY3RzZmhAVAW1x3+ +QjwwxhE4Ttkut3BE3+sh0w68vEpYRzvVToyDtBU8X/jRltAZWw4yNp6cEU/hfF5yr aIixqNnmSbdbSW5RRCwsD8Eh4bE6Owm4yNpdop7Nxr/QhjUgGKyXoBWusnUWAIL/4h eQ2nvw3El/2nQ== Date: Tue, 24 Jan 2023 09:05:58 -0600 From: Bjorn Helgaas To: "Rafael J. Wysocki" Cc: Geert Uytterhoeven , Len Brown , Greg Kroah-Hartman , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Bjorn Helgaas Subject: Re: [PATCH] PM: runtime: Simplify __rpm_get_callback() Message-ID: <20230124150558.GA1061961@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 24, 2023 at 03:45:50PM +0100, Rafael J. Wysocki wrote: > On Tue, Jan 24, 2023 at 3:37 PM Geert Uytterhoeven wrote: > > On Tue, Jan 24, 2023 at 3:18 PM Rafael J. Wysocki wrote: > > > On Tue, Jan 24, 2023 at 12:20 PM Geert Uytterhoeven > > > wrote: > > > > On Thu, Dec 15, 2022 at 7:23 PM Bjorn Helgaas wrote: > > > > > From: Bjorn Helgaas > > > > > > > > > > Simplify __rpm_get_callback() slightly by returning as soon as the return > > > > > value is known. No functional change intended. > > > > > > > > > > Signed-off-by: Bjorn Helgaas > > > > > > > > Thanks for your patch, which is now commit 650bdddb6b311705 ("PM: > > > > runtime: Simplify __rpm_get_callback()") in pm/linux-next. > > > > > > > > > --- a/drivers/base/power/runtime.c > > > > > +++ b/drivers/base/power/runtime.c > > > > > @@ -20,8 +20,7 @@ typedef int (*pm_callback_t)(struct device *); > > > > > > > > > > static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset) > > > > > { > > > > > - pm_callback_t cb; > > > > > - const struct dev_pm_ops *ops; > > > > > + const struct dev_pm_ops *ops = NULL; > > > > > > > > > > if (dev->pm_domain) > > > > > ops = &dev->pm_domain->ops; > > > > > @@ -31,18 +30,14 @@ static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset) > > > > > ops = dev->class->pm; > > > > > else if (dev->bus && dev->bus->pm) > > > > > ops = dev->bus->pm; > > > > > - else > > > > > - ops = NULL; > > > > > > > > > > if (ops) > > > > > - cb = *(pm_callback_t *)((void *)ops + cb_offset); > > > > > - else > > > > > - cb = NULL; > > > > > + return *(pm_callback_t *)((void *)ops + cb_offset); > > > > > > > > This is a change in behavior in case the callback turns out to be NULL: > > > > - before, it would fall back to the driver-specific callback below, > > > > - after, it always returns NULL. > > > > > > Good point and sorry for missing this! > > > > > > > > > > > > > - if (!cb && dev->driver && dev->driver->pm) > > > > > - cb = *(pm_callback_t *)((void *)dev->driver->pm + cb_offset); > > > > > + if (dev->driver && dev->driver->pm) > > > > > + return *(pm_callback_t *)((void *)dev->driver->pm + cb_offset); > > > > > > > > > > - return cb; > > > > > + return NULL; > > > > > } > > > > > > > > > > Something like the patch below (modulo gmail-induced whitespace > > > breakage) should restore the previous behavior if I'm not mistaken: > > > > > > --- > > > drivers/base/power/runtime.c | 9 +++++++-- > > > 1 file changed, 7 insertions(+), 2 deletions(-) > > > > > > Index: linux-pm/drivers/base/power/runtime.c > > > =================================================================== > > > --- linux-pm.orig/drivers/base/power/runtime.c > > > +++ linux-pm/drivers/base/power/runtime.c > > > @@ -31,8 +31,13 @@ static pm_callback_t __rpm_get_callback( > > > else if (dev->bus && dev->bus->pm) > > > ops = dev->bus->pm; > > > > > > - if (ops) > > > - return *(pm_callback_t *)((void *)ops + cb_offset); > > > + if (ops) { > > > + pm_callback_t cb; > > > + > > > + cb = *(pm_callback_t *)((void *)ops + cb_offset); > > > + if (cb) > > > + return cb; > > > + } > > > > > > if (dev->driver && dev->driver->pm) > > > return *(pm_callback_t *)((void *)dev->driver->pm + cb_offset); > > > > Which is now more complex than the original? > > Arguably so. > > OK, I'll drop the commit in question then, sorry Bjorn. Really sorry about this. Think I'm all out of brown paper bags :( Thanks for catching this, Geert, and sorry for all the time you had to spend debugging it. Bjorn