From patchwork Thu Apr 29 19:03:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Ekstrand X-Patchwork-Id: 12231717 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 AB9B8C43461 for ; Thu, 29 Apr 2021 19:04:31 +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 5005D613FF for ; Thu, 29 Apr 2021 19:04:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5005D613FF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=jlekstrand.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 039066F473; Thu, 29 Apr 2021 19:04:12 +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 001F66F469 for ; Thu, 29 Apr 2021 19:04:07 +0000 (UTC) Received: by mail-pl1-x631.google.com with SMTP id y1so19641471plg.11 for ; Thu, 29 Apr 2021 12:04:07 -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=fsllfSQGOYUIVLhl3Co0QJ3iUTIL9mD5TCD1jQqxlak=; b=0JLO3oPBSl/OuSVLQUj5GL/JP083CI5pZJwwwDpJhz/es+1ZBP8/713CCxT2FXUZCR hkd3F6zQ2978isFiyIFZh9D3I6rT8yuDROP7rlcp94dw8ZleLCWoC1e3QhmXZfAMnkBF igrB4mDDzCfILKvRQMkkEx4TVSpIB7JGE/YVLQ8oOviQ96FAnqggpL5RbrPCeqbSB0s3 YXvjBvXHq4znc7aSR8ZBa1N435f0HTIx/JuHOR8FNajkBQLnw2D9biyQRVxuwRqqVuPm 2YMJh5hDnLIHUIp9tkbc0zzW0QMCS09lobHVlP5M13xhA8uXe66slU98Tb8R4ZV+cxMK PvSA== 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=fsllfSQGOYUIVLhl3Co0QJ3iUTIL9mD5TCD1jQqxlak=; b=K2fbknbQSoKDwYQbmpknrs164ss0b9kxd8wgHfARKlO5z62k3BthoSsCDUUubZ/wcW QsuFQh3iUYlMym6ucRM/iw6qA03Sg5K/9yewUiMdPh4u8IK1zROsg5i4hNLP8iDPJTJA ItZPxQ0Q424XZovWMSBiszU2pkU5qhuHFdeVjy6oz2qofx3MF3VN8xkDhjIRvRjAYcVW 2NLyvQpMj6ewS4aGEepatZzf/G5he87afmq2aMj2Cv1A+CB8awwouO9E3CbvCFgtpNSH /uLD3p2yV+NW9Ta+SD6O1qnhEx8Ln9B6kT0WvGhc4HxM9z7ORlbxYmkT26Zm3H/G+cRS ulhQ== X-Gm-Message-State: AOAM5336EgxKav1yA3wJrnA1qN18AUZjFcavazY+xS3q9Z8AvvN8llX+ J7+Qne5K8I8m2XzdpI/eQET0lA== X-Google-Smtp-Source: ABdhPJy/28FBfImpPfPj8rWo4O8y1RZML2f5YaBVrh25GwJkCC5AnQQ0zdduDyDk8PisY4PhIImn5g== X-Received: by 2002:a17:90a:f009:: with SMTP id bt9mr1306677pjb.137.1619723047500; Thu, 29 Apr 2021 12:04:07 -0700 (PDT) Received: from omlet.lan ([134.134.139.83]) by smtp.gmail.com with ESMTPSA id b21sm3114405pji.39.2021.04.29.12.04.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Apr 2021 12:04:06 -0700 (PDT) From: Jason Ekstrand To: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: [PATCH 13/25] drm/i915: Stop manually RCU banging in reset_stats_ioctl (v2) Date: Thu, 29 Apr 2021 14:03:28 -0500 Message-Id: <20210429190340.1555632-14-jason@jlekstrand.net> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210429190340.1555632-1-jason@jlekstrand.net> References: <20210429190340.1555632-1-jason@jlekstrand.net> MIME-Version: 1.0 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: , Cc: Daniel Vetter , Jason Ekstrand Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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 8e254d83d65f2..c073d5939482b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c @@ -2091,16 +2091,13 @@ 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 @@ -2117,10 +2114,8 @@ 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 0b44333eb7033..8571c5c1509a7 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1840,19 +1840,13 @@ 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();