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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 2464EC4361B for ; Sun, 6 Dec 2020 16:39:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D4D6A230FA for ; Sun, 6 Dec 2020 16:39:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727099AbgLFQj1 (ORCPT ); Sun, 6 Dec 2020 11:39:27 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:58988 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726186AbgLFQj0 (ORCPT ); Sun, 6 Dec 2020 11:39:26 -0500 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1607272724; 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=orscdnWsxTjeOjrX4mZ7RlgaGlM/iHr3hxGeVG/5B5o=; b=S9U+yLW+RMD4XJ+DVjlUuG1Ta3scM6aUrIt7ysUfUnpo2Lk9yrcK1AlcgrZWgFWCtYoJTF VExnxFo/ryb4R7eRQEVwMsDGha92iA0oI81k+3gGLFB1nonwAisjC3/jKTSUf/nGy1d64W /i1uYHhHy/jPj6waERlxa7GsrP6eM2yH0numGnZwlG3dEBTbqM59AhAzaFX9Pkk1y9qak3 dhXHo9nnSGnB608LNXSZ0BSANnW+ESKfmIzwLrnY3Zp+ef11yigXhYhPrhNWafb4cMW6lM JyoZkKlnRO1jdjGoihuwGfLZqyXfJAFPDlho62hQLrm5QKAPcdCuOpSMM3JdkA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1607272724; 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=orscdnWsxTjeOjrX4mZ7RlgaGlM/iHr3hxGeVG/5B5o=; b=AksEazRjmD+yqQmgK8+KYrxZfIF8IEb97GXwe2YdDqzKrwXlC8Rc+QhlrKd/lk5AZdXYm6 zdJsYoIctUvQBdCw== To: Jerry Snitselaar , linux-kernel@vger.kernel.org Cc: linux-integrity@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Jani Nikula , Rodrigo Vivi , David Airlie , Daniel Vetter , Jarkko Sakkinen , Jason Gunthorpe , Peter Huewe , James Bottomley , Matthew Garrett , Hans de Goede , Peter Zijlstra Subject: Re: [PATCH v3 2/4] drm/i915/pmu: Use kstat_irqs to get interrupt count In-Reply-To: <20201205014340.148235-3-jsnitsel@redhat.com> References: <20201205014340.148235-1-jsnitsel@redhat.com> <20201205014340.148235-3-jsnitsel@redhat.com> Date: Sun, 06 Dec 2020 17:38:44 +0100 Message-ID: <875z5e99ez.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 04 2020 at 18:43, Jerry Snitselaar wrote: > Now that kstat_irqs is exported, get rid of count_interrupts in > i915_pmu.c > --- a/drivers/gpu/drm/i915/i915_pmu.c > +++ b/drivers/gpu/drm/i915/i915_pmu.c > @@ -423,22 +423,6 @@ static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer) > return HRTIMER_RESTART; > } > > -static u64 count_interrupts(struct drm_i915_private *i915) > -{ > - /* open-coded kstat_irqs() */ > - struct irq_desc *desc = irq_to_desc(i915->drm.pdev->irq); > - u64 sum = 0; > - int cpu; > - > - if (!desc || !desc->kstat_irqs) > - return 0; > - > - for_each_possible_cpu(cpu) > - sum += *per_cpu_ptr(desc->kstat_irqs, cpu); > - > - return sum; > -} May I ask why this has been merged in the first place? Nothing in a driver has ever to fiddle with the internals of an irq descriptor. We have functions for properly accessing them. Just because C allows to fiddle with everything is not a justification. If the required function is not exported then adding the export with a proper explanation is not asked too much. Also this lacks protection or at least a comment why this can be called safely and is not subject to a concurrent removal of the irq descriptor. The same problem exists when calling kstat_irqs(). It's even documented at the top of the function. Thanks, tglx