From patchwork Thu May 27 16:26:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Ekstrand X-Patchwork-Id: 12284855 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=-16.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 22C27C47092 for ; Thu, 27 May 2021 16:27:58 +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 E47CD61003 for ; Thu, 27 May 2021 16:27:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E47CD61003 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=jlekstrand.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E7D286F463; Thu, 27 May 2021 16:27:40 +0000 (UTC) Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by gabe.freedesktop.org (Postfix) with ESMTPS id CD5DB6F44E for ; Thu, 27 May 2021 16:27:14 +0000 (UTC) Received: by mail-pl1-x631.google.com with SMTP id v12so211805plo.10 for ; Thu, 27 May 2021 09:27:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jlekstrand-net.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=nXXZSOVAXoArgl6T1nQauVAu5cjGHtdbhlLvXep877s=; b=oivzI9EmMb/hA1UqJXEaYBIrp0n1FFB82L3FgEqRveN6ad4nARl5gOW5z+cjAMFnVs lnGa2ZwkyLZorhpRGw4e3W0dmJaNkutHzcZVblLB5DWxSecvnHrovDXhAt2IafZ4y9iC Vfsg3LyuOLsw5C9xfIWiL/Oe5EZAW1cH8Kw+WsZuUWTrMwSBA7LrUceoTjWV7ZjTCWvN bh7q2Bi6UuWUTdP3s3eeBwmD+5qNdmDT5X5XVw0duYlWZkdE4vK/Fce79MlkjupsQZBX ngErf8mfYvgk+w7boh18nIlXdQ9UL33fJimWid3T3LbYjVotQ56U0MFGQHx2JzuDj6/z ioTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=nXXZSOVAXoArgl6T1nQauVAu5cjGHtdbhlLvXep877s=; b=D3hsc36ThBriGXVKoeu+FspLj5jUiBaIB2W0wzAkN3YVAPo8TgNYDFcEcC5LYf3wzM BERXHzxNWk2sCBltJ2cVlAkwQYU9FocHBEiMV6jzgwtW3JsoCz3dzffQnf/BTSZ8x6vr Zgt7b3+fowzLNmZCTFi248H04Xlely91+PvIKxjVuh88n2ZWOUJik66FLsWjEHzTXiOu JjeYZnoMswS/fT5rnHXwpNT+/rSjuBRvMvC/JopxVbOS7SO6B+b4kR6SpboQF5c2GLc7 gY8uzDjIzDmAWZDw0EUi6kO/7sUrsBCJcyO3U+yspFEcCaWr2nJ1Bjsi0JbC67impRJC i9Xg== X-Gm-Message-State: AOAM5302HSHRMzDkvG6OGIXzWMScr6i5Gg3H78cTc35MhK+Q7AFRS6NX UjSVkzxqhAgVWUSbB2uYVILdh1vxODtKnQ== X-Google-Smtp-Source: ABdhPJyotrqvjM4D3hGiSjuiY+YgW7QvgICzu083MEshtquIo9QG3kOLV/Roo87DEqlggOHUqLDS+w== X-Received: by 2002:a17:90a:3ec3:: with SMTP id k61mr10328774pjc.48.1622132834045; Thu, 27 May 2021 09:27:14 -0700 (PDT) Received: from omlet.com ([134.134.139.83]) by smtp.gmail.com with ESMTPSA id h9sm2298711pja.42.2021.05.27.09.27.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 May 2021 09:27:13 -0700 (PDT) From: Jason Ekstrand To: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Date: Thu, 27 May 2021 11:26:34 -0500 Message-Id: <20210527162650.1182544-14-jason@jlekstrand.net> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210527162650.1182544-1-jason@jlekstrand.net> References: <20210527162650.1182544-1-jason@jlekstrand.net> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 13/29] drm/i915: Stop manually RCU banging in reset_stats_ioctl (v2) X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel Vetter Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" As far as I can tell, the only real reason for this is to avoid taking a reference to the i915_gem_context. The cost of those two atomics probably pales in comparison to the cost of the ioctl itself so we're really not buying ourselves anything here. We're about to make context lookup a tiny bit more complicated, so let's get rid of the one hand- rolled case. Some usermode drivers such as our Vulkan driver call GET_RESET_STATS on every execbuf so the perf here could theoretically be an issue. If this ever does become a performance issue for any such userspace drivers, they can use set CONTEXT_PARAM_RECOVERABLE to false and look for -EIO coming from execbuf to check for hangs instead. v2 (Daniel Vetter): - Add a comment in the commit message about recoverable contexts Signed-off-by: Jason Ekstrand Reviewed-by: Daniel Vetter --- drivers/gpu/drm/i915/gem/i915_gem_context.c | 13 ++++--------- drivers/gpu/drm/i915/i915_drv.h | 8 +------- 2 files changed, 5 insertions(+), 16 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c index 2b9207b557cc9..910d31cb043e9 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c @@ -2090,16 +2090,13 @@ int i915_gem_context_reset_stats_ioctl(struct drm_device *dev, struct drm_i915_private *i915 = to_i915(dev); struct drm_i915_reset_stats *args = data; struct i915_gem_context *ctx; - int ret; if (args->flags || args->pad) return -EINVAL; - ret = -ENOENT; - rcu_read_lock(); - ctx = __i915_gem_context_lookup_rcu(file->driver_priv, args->ctx_id); + ctx = i915_gem_context_lookup(file->driver_priv, args->ctx_id); if (!ctx) - goto out; + return -ENOENT; /* * We opt for unserialised reads here. This may result in tearing @@ -2116,10 +2113,8 @@ int i915_gem_context_reset_stats_ioctl(struct drm_device *dev, args->batch_active = atomic_read(&ctx->guilty_count); args->batch_pending = atomic_read(&ctx->active_count); - ret = 0; -out: - rcu_read_unlock(); - return ret; + i915_gem_context_put(ctx); + return 0; } /* GEM context-engines iterator: for_each_gem_engine() */ diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 39b5e019c1a5b..48316d273af66 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1857,19 +1857,13 @@ struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev, struct dma_buf *i915_gem_prime_export(struct drm_gem_object *gem_obj, int flags); -static inline struct i915_gem_context * -__i915_gem_context_lookup_rcu(struct drm_i915_file_private *file_priv, u32 id) -{ - return xa_load(&file_priv->context_xa, id); -} - static inline struct i915_gem_context * i915_gem_context_lookup(struct drm_i915_file_private *file_priv, u32 id) { struct i915_gem_context *ctx; rcu_read_lock(); - ctx = __i915_gem_context_lookup_rcu(file_priv, id); + ctx = xa_load(&file_priv->context_xa, id); if (ctx && !kref_get_unless_zero(&ctx->ref)) ctx = NULL; rcu_read_unlock();