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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 5FFB5C432BE for ; Tue, 17 Aug 2021 09:39:36 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 2F66F60184 for ; Tue, 17 Aug 2021 09:39:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2F66F60184 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 97CB66E14C; Tue, 17 Aug 2021 09:39:34 +0000 (UTC) Received: from mail-wr1-x42c.google.com (mail-wr1-x42c.google.com [IPv6:2a00:1450:4864:20::42c]) by gabe.freedesktop.org (Postfix) with ESMTPS id D58196E14B for ; Tue, 17 Aug 2021 09:39:32 +0000 (UTC) Received: by mail-wr1-x42c.google.com with SMTP id h13so27679675wrp.1 for ; Tue, 17 Aug 2021 02:39:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=pJSxWYLKnDA66bheHGHNbiU7aF7BawRxoKGnFTnRlBM=; b=AQgwWDyF9STNIoiaoUboFEI4Lf1WzX+DQA96iH4l0yrFtip5OvC7LLxkDaJGX9u26v /bDezuaUVZ7+xAMbNLxMIueq9aW5414w5jgY3YrWptJq0w0s8PKB6kMN8WHF3Qwew+XB lzRgJs1mHZAzeH6Kojx77Z5irfJmIYnfCxSZg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=pJSxWYLKnDA66bheHGHNbiU7aF7BawRxoKGnFTnRlBM=; b=gJEVtNyJFS87WFxjQ0IzGBfJtThCrYNGGR7yj7S/8Uc0vhSXFHygFRU+d+8TELMhDy bR3l5HJMfxv+1EopmWY+JPUGC7WY4bw8ttw00uJDdWoVUMH3Ryzfn9NGVojqf7tEVQe5 stQNee4JWJ4n9ZEz7fiS24vNZfEhpTpZVsMDhHzudyRmBHgYcnpEqzwNAOLSHyYK1ELA szR36SOWsvXqVbKpQFWF7zPqt7BD0cvs9onVgmGaH7Aj/hMAB+rlxmnzz4RdCkWXrKcA H/3np8k2lv+B2hVD47DJTVVW2xgSycK9QKxBOV6jTUnzjLe9RNsHBQlIj7wPwAwzjB2Q KnOg== X-Gm-Message-State: AOAM532eLkgDFU8il/m+gB+5uwLYh47Ll3yQfAAF1t7GVXnet7M1wlDR SER/ksYpbEcNcikUSwffVRG62A== X-Google-Smtp-Source: ABdhPJx219a4HpbSUMZuXDX4kDcHSoRjr6JHVpn98bgWjw4UDPC64d7onillyUh7s7eObVJW1jm9eA== X-Received: by 2002:adf:e30c:: with SMTP id b12mr2805809wrj.347.1629193171354; Tue, 17 Aug 2021 02:39:31 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id b201sm1471683wmb.6.2021.08.17.02.39.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Aug 2021 02:39:30 -0700 (PDT) Date: Tue, 17 Aug 2021 11:39:29 +0200 From: Daniel Vetter To: Matthew Brost Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, daniel.vetter@ffwll.ch Subject: Re: [PATCH 02/22] drm/i915/guc: Fix outstanding G2H accounting Message-ID: References: <20210816135139.10060-1-matthew.brost@intel.com> <20210816135139.10060-3-matthew.brost@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210816135139.10060-3-matthew.brost@intel.com> X-Operating-System: Linux phenom 5.10.0-7-amd64 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Aug 16, 2021 at 06:51:19AM -0700, Matthew Brost wrote: > A small race that could result in incorrect accounting of the number > of outstanding G2H. Basically prior to this patch we did not increment > the number of outstanding G2H if we encoutered a GT reset while sending > a H2G. This was incorrect as the context state had already been updated > to anticipate a G2H response thus the counter should be incremented. > > Fixes: f4eb1f3fe946 ("drm/i915/guc: Ensure G2H response has space in buffer") > Signed-off-by: Matthew Brost > Cc: > --- > drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > index 69faa39da178..b5d3972ae164 100644 > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > @@ -360,11 +360,13 @@ static int guc_submission_send_busy_loop(struct intel_guc *guc, > { > int err; > > - err = intel_guc_send_busy_loop(guc, action, len, g2h_len_dw, loop); > - > - if (!err && g2h_len_dw) > + if (g2h_len_dw) > atomic_inc(&guc->outstanding_submission_g2h); > > + err = intel_guc_send_busy_loop(guc, action, len, g2h_len_dw, loop); I'm majorly confused by the _busy_loop naming scheme, especially here. Like "why do we want to send a busy loop comand to guc, this doesn't make sense". It seems like you're using _busy_loop as a suffix for "this is ok to be called in atomic context". The linux kernel bikeshed for this is generally _atomic() (or _in_atomic() or something like that). Would be good to rename to make this slightly less confusing. -Daniel > + if (err == -EBUSY && g2h_len_dw) > + atomic_dec(&guc->outstanding_submission_g2h); > + > return err; > } > > -- > 2.32.0 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch