From patchwork Thu Oct 3 21:01:00 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11173385 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1DF391709 for ; Thu, 3 Oct 2019 21:01:38 +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 0698020862 for ; Thu, 3 Oct 2019 21:01:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0698020862 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk 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 434E96EA86; Thu, 3 Oct 2019 21:01:33 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 05A6A6EA86; Thu, 3 Oct 2019 21:01:27 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 18715183-1500050 for multiple; Thu, 03 Oct 2019 22:01:04 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Subject: [PATCH 5/5] drm/mm: Use clear_bit_unlock() for releasing the drm_mm_node() Date: Thu, 3 Oct 2019 22:01:00 +0100 Message-Id: <20191003210100.22250-5-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191003210100.22250-1-chris@chris-wilson.co.uk> References: <20191003210100.22250-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dri-devel@lists.freedesktop.org, tvrtko.ursulin@intel.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" A few callers need to serialise the destruction of their drm_mm_node and ensure it is removed from the drm_mm before freeing. However, to be completely sure that any access from another thread is complete before we free the struct, we require the RELEASE semantics of clear_bit_unlock(). This allows the conditional locking such as Thread A Thread B mutex_lock(mm_lock); if (drm_mm_node_allocated(node)) { drm_mm_node_remove(node); mutex_lock(mm_lock); mutex_unlock(mm_lock); drm_mm_node_remove(node); mutex_unlock(mm_lock); } kfree(node); to serialise correctly without any lingering accesses from A to the freed node. Allocation / insertion of the node is assumed never to race with removal or eviction scanning. Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin --- drivers/gpu/drm/drm_mm.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c index a9cab5e53731..2a6e34663146 100644 --- a/drivers/gpu/drm/drm_mm.c +++ b/drivers/gpu/drm/drm_mm.c @@ -424,9 +424,9 @@ int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node) node->mm = mm; + __set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags); list_add(&node->node_list, &hole->node_list); drm_mm_interval_tree_add_node(hole, node); - __set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags); node->hole_size = 0; rm_hole(hole); @@ -543,9 +543,9 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm, node->color = color; node->hole_size = 0; + __set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags); list_add(&node->node_list, &hole->node_list); drm_mm_interval_tree_add_node(hole, node); - __set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags); rm_hole(hole); if (adj_start > hole_start) @@ -589,11 +589,12 @@ void drm_mm_remove_node(struct drm_mm_node *node) drm_mm_interval_tree_remove(node, &mm->interval_tree); list_del(&node->node_list); - __clear_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags); if (drm_mm_hole_follows(prev_node)) rm_hole(prev_node); add_hole(prev_node); + + clear_bit_unlock(DRM_MM_NODE_ALLOCATED_BIT, &node->flags); } EXPORT_SYMBOL(drm_mm_remove_node); @@ -614,6 +615,7 @@ void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new) *new = *old; + __set_bit(DRM_MM_NODE_ALLOCATED_BIT, &new->flags); list_replace(&old->node_list, &new->node_list); rb_replace_node_cached(&old->rb, &new->rb, &mm->interval_tree); @@ -627,8 +629,7 @@ void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new) &mm->holes_addr); } - __clear_bit(DRM_MM_NODE_ALLOCATED_BIT, &old->flags); - __set_bit(DRM_MM_NODE_ALLOCATED_BIT, &new->flags); + clear_bit_unlock(DRM_MM_NODE_ALLOCATED_BIT, &old->flags); } EXPORT_SYMBOL(drm_mm_replace_node);