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 X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33C64C433E0 for ; Tue, 30 Jun 2020 01:22:05 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D6A922078A for ; Tue, 30 Jun 2020 01:22:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="ikI6Lg8m" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D6A922078A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 49wmmV6Wg3zDqXB for ; Tue, 30 Jun 2020 11:22:02 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) (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 lists.ozlabs.org (Postfix) with ESMTPS id 49wmkQ4yZlzDqM1 for ; Tue, 30 Jun 2020 11:20:14 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=ikI6Lg8m; dkim-atps=neutral Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 49wmkQ2hBsz9sRk; Tue, 30 Jun 2020 11:20:14 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1593480014; bh=m4WmUHkQALcylgOZ+dnZgVmqWAg4+2S6xGRs4SSlSBM=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=ikI6Lg8m9XC/26DR9jOlGqXQnUkgHNg5eDc/+8BLJTpUAMNx2TUc1h5d6sLkUDMFN 5ThhMYkcsrcWj63leBuYbrJKsPmBzu33txgdCW8tYjH13Lc9HTux5gKIDIGlRBAYlV o659ukNU1Q6YScNpWpClFzXsi9C+gLmGWVZCxHCB/sWrvOd6xpSgBpkUfLj+ZAen8x SvtvauV6RXJop5KfBwzzw8J+E5jUa3KAT1WZMtMCvqLDnu1X6vvap2tzzorpSaNbWS 0wcNm461okXd0FO2Ms5H36FmzvW1yVPQYiDY0t2XaUZHJ1g4v8N2w3HmPBG3OBXfcc RlV76H91dmj4Q== From: Michael Ellerman To: Joel Stanley , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] powerpc: Warn about use of smt_snooze_delay In-Reply-To: <20200625100349.2408899-1-joel@jms.id.au> References: <20200625100349.2408899-1-joel@jms.id.au> Date: Tue, 30 Jun 2020 11:22:29 +1000 Message-ID: <87366d8i0a.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ego@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Joel Stanley writes: > It's not done anything for a long time. Save the percpu variable, and > emit a warning to remind users to not expect it to do anything. > > Signed-off-by: Joel Stanley > --- > arch/powerpc/kernel/sysfs.c | 41 +++++++++++++------------------------ > 1 file changed, 14 insertions(+), 27 deletions(-) > > diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c > index 571b3259697e..530ae92bc46d 100644 > --- a/arch/powerpc/kernel/sysfs.c > +++ b/arch/powerpc/kernel/sysfs.c > @@ -32,29 +32,25 @@ > > static DEFINE_PER_CPU(struct cpu, cpu_devices); > > -/* > - * SMT snooze delay stuff, 64-bit only for now > - */ > - > #ifdef CONFIG_PPC64 > > -/* Time in microseconds we delay before sleeping in the idle loop */ > -static DEFINE_PER_CPU(long, smt_snooze_delay) = { 100 }; > +/* > + * Snooze delay has not been hooked up since 3fa8cad82b94 ("powerpc/pseries/cpuidle: > + * smt-snooze-delay cleanup.") and has been broken even longer. As was foretold in > + * 2014: > + * > + * "ppc64_util currently utilises it. Once we fix ppc64_util, propose to clean > + * up the kernel code." > + * > + * At some point in the future this code should be removed. > + */ > > static ssize_t store_smt_snooze_delay(struct device *dev, > struct device_attribute *attr, > const char *buf, > size_t count) > { > - struct cpu *cpu = container_of(dev, struct cpu, dev); > - ssize_t ret; > - long snooze; > - > - ret = sscanf(buf, "%ld", &snooze); > - if (ret != 1) > - return -EINVAL; > - > - per_cpu(smt_snooze_delay, cpu->dev.id) = snooze; > + WARN_ON_ONCE("smt_snooze_delay sysfs file has no effect\n"); We shouldn't have user-triggerable WARNs. I think this should just be a pr_warn_ratelimited(), maybe including current->comm & pid. cheers