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=-16.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 79F79C432BE for ; Tue, 31 Aug 2021 09:29:50 +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 1F2A4606A5 for ; Tue, 31 Aug 2021 09:29:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 1F2A4606A5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com 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 C476B897C5; Tue, 31 Aug 2021 09:29:47 +0000 (UTC) Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0610D8975F; Tue, 31 Aug 2021 09:29:45 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10092"; a="198673876" X-IronPort-AV: E=Sophos;i="5.84,366,1620716400"; d="scan'208";a="198673876" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2021 02:29:45 -0700 X-IronPort-AV: E=Sophos;i="5.84,366,1620716400"; d="scan'208";a="531025500" Received: from wenqitan-mobl1.ger.corp.intel.com (HELO [10.252.59.180]) ([10.252.59.180]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2021 02:29:41 -0700 Subject: Re: [PATCH 10/11] drm/i915: use xa_lock/unlock for fpriv->vm_xa lookups To: Daniel Vetter , DRI Development Cc: Intel Graphics Development , Daniel Vetter , Jon Bloomfield , Chris Wilson , Joonas Lahtinen , =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= , Matthew Auld , Lionel Landwerlin , Dave Airlie , Jason Ekstrand References: <20210813203033.3179400-1-daniel.vetter@ffwll.ch> <20210813203033.3179400-10-daniel.vetter@ffwll.ch> From: Maarten Lankhorst Message-ID: Date: Tue, 31 Aug 2021 11:29:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210813203033.3179400-10-daniel.vetter@ffwll.ch> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US 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" Op 13-08-2021 om 22:30 schreef Daniel Vetter: > We don't need the absolute speed of rcu for this. And > i915_address_space in general dont need rcu protection anywhere else, > after we've made gem contexts and engines a lot more immutable. > > Note that this semantically reverts > > commit aabbe344dc3ca5f7d8263a02608ba6179e8a4499 > Author: Chris Wilson > Date: Fri Aug 30 19:03:25 2019 +0100 > > drm/i915: Use RCU for unlocked vm_idr lookup > > except we have the conversion from idr to xarray in between. > > Signed-off-by: Daniel Vetter > Cc: Jon Bloomfield > Cc: Chris Wilson > Cc: Maarten Lankhorst > Cc: Joonas Lahtinen > Cc: Daniel Vetter > Cc: "Thomas Hellström" > Cc: Matthew Auld > Cc: Lionel Landwerlin > Cc: Dave Airlie > Cc: Jason Ekstrand > --- > drivers/gpu/drm/i915/i915_drv.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > index 005b1cec7007..e37fac8fac0c 100644 > --- a/drivers/gpu/drm/i915/i915_drv.h > +++ b/drivers/gpu/drm/i915/i915_drv.h > @@ -1881,11 +1881,11 @@ i915_gem_vm_lookup(struct drm_i915_file_private *file_priv, u32 id) > { > struct i915_address_space *vm; > > - rcu_read_lock(); > + xa_lock(&file_priv->vm_xa); > vm = xa_load(&file_priv->vm_xa, id); > if (vm && !kref_get_unless_zero(&vm->ref)) > vm = NULL; I think this could be a plain i915_vm_get now, kref_get_unless_zero is not guarded by RCU any more. > - rcu_read_unlock(); > + xa_unlock(&file_priv->vm_xa); > > return vm; > } Apart from that, all looks good. With this fix, for patch 2-11: Reviewed-by: Maarten Lankhorst 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=-16.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 3A68BC4320A for ; Tue, 31 Aug 2021 09:29:48 +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 EFCA660F12 for ; Tue, 31 Aug 2021 09:29:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org EFCA660F12 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com 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 8CA318975F; Tue, 31 Aug 2021 09:29:47 +0000 (UTC) Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0610D8975F; Tue, 31 Aug 2021 09:29:45 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10092"; a="198673876" X-IronPort-AV: E=Sophos;i="5.84,366,1620716400"; d="scan'208";a="198673876" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2021 02:29:45 -0700 X-IronPort-AV: E=Sophos;i="5.84,366,1620716400"; d="scan'208";a="531025500" Received: from wenqitan-mobl1.ger.corp.intel.com (HELO [10.252.59.180]) ([10.252.59.180]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2021 02:29:41 -0700 To: Daniel Vetter , DRI Development Cc: Intel Graphics Development , Daniel Vetter , Jon Bloomfield , Chris Wilson , Joonas Lahtinen , =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= , Matthew Auld , Lionel Landwerlin , Dave Airlie , Jason Ekstrand References: <20210813203033.3179400-1-daniel.vetter@ffwll.ch> <20210813203033.3179400-10-daniel.vetter@ffwll.ch> From: Maarten Lankhorst Message-ID: Date: Tue, 31 Aug 2021 11:29:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210813203033.3179400-10-daniel.vetter@ffwll.ch> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US Subject: Re: [Intel-gfx] [PATCH 10/11] drm/i915: use xa_lock/unlock for fpriv->vm_xa lookups 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: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Op 13-08-2021 om 22:30 schreef Daniel Vetter: > We don't need the absolute speed of rcu for this. And > i915_address_space in general dont need rcu protection anywhere else, > after we've made gem contexts and engines a lot more immutable. > > Note that this semantically reverts > > commit aabbe344dc3ca5f7d8263a02608ba6179e8a4499 > Author: Chris Wilson > Date: Fri Aug 30 19:03:25 2019 +0100 > > drm/i915: Use RCU for unlocked vm_idr lookup > > except we have the conversion from idr to xarray in between. > > Signed-off-by: Daniel Vetter > Cc: Jon Bloomfield > Cc: Chris Wilson > Cc: Maarten Lankhorst > Cc: Joonas Lahtinen > Cc: Daniel Vetter > Cc: "Thomas Hellström" > Cc: Matthew Auld > Cc: Lionel Landwerlin > Cc: Dave Airlie > Cc: Jason Ekstrand > --- > drivers/gpu/drm/i915/i915_drv.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > index 005b1cec7007..e37fac8fac0c 100644 > --- a/drivers/gpu/drm/i915/i915_drv.h > +++ b/drivers/gpu/drm/i915/i915_drv.h > @@ -1881,11 +1881,11 @@ i915_gem_vm_lookup(struct drm_i915_file_private *file_priv, u32 id) > { > struct i915_address_space *vm; > > - rcu_read_lock(); > + xa_lock(&file_priv->vm_xa); > vm = xa_load(&file_priv->vm_xa, id); > if (vm && !kref_get_unless_zero(&vm->ref)) > vm = NULL; I think this could be a plain i915_vm_get now, kref_get_unless_zero is not guarded by RCU any more. > - rcu_read_unlock(); > + xa_unlock(&file_priv->vm_xa); > > return vm; > } Apart from that, all looks good. With this fix, for patch 2-11: Reviewed-by: Maarten Lankhorst