From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756014AbaA1XYh (ORCPT ); Tue, 28 Jan 2014 18:24:37 -0500 Received: from mail-qa0-f52.google.com ([209.85.216.52]:64398 "EHLO mail-qa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755860AbaA1XWD (ORCPT ); Tue, 28 Jan 2014 18:22:03 -0500 From: Tejun Heo To: gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, stern@rowland.harvard.edu, JBottomley@parallels.com, bhelgaas@google.com, Tejun Heo Subject: [PATCH 05/11] kernfs: remove KERNFS_ACTIVE_REF and add kernfs_lockdep() Date: Tue, 28 Jan 2014 18:21:45 -0500 Message-Id: <1390951311-15325-6-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.8.5.3 In-Reply-To: <1390951311-15325-1-git-send-email-tj@kernel.org> References: <1390951311-15325-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There currently are two mechanisms gating active ref lockdep annotations - KERNFS_LOCKDEP flag and KERNFS_ACTIVE_REF type mask. The former disables lockdep annotations in kernfs_get/put_active() while the latter disables all of kernfs_deactivate(). While KERNFS_ACTIVE_REF also behaves as an optimization to skip the deactivation step for non-file nodes, the benefit is marginal and it needlessly diverges code paths. Let's drop KERNFS_ACTIVE_REF and use KERNFS_LOCKDEP in kernfs_deactivate() too. While at it, add a test helper kernfs_lockdep() to test KERNFS_LOCKDEP flag so that it's more convenient and the related code can be compiled out when not enabled. Signed-off-by: Tejun Heo --- fs/kernfs/dir.c | 30 ++++++++++++++++++++---------- include/linux/kernfs.h | 1 - 2 files changed, 20 insertions(+), 11 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 8459f61..5cf137b 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -22,6 +22,15 @@ DEFINE_MUTEX(kernfs_mutex); #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) +static bool kernfs_lockdep(struct kernfs_node *kn) +{ +#ifdef CONFIG_DEBUG_LOCK_ALLOC + return kn->flags & KERNFS_LOCKDEP; +#else + return false; +#endif +} + /** * kernfs_name_hash * @name: Null terminated string to hash @@ -144,7 +153,7 @@ struct kernfs_node *kernfs_get_active(struct kernfs_node *kn) if (!atomic_inc_unless_negative(&kn->active)) return NULL; - if (kn->flags & KERNFS_LOCKDEP) + if (kernfs_lockdep(kn)) rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_); return kn; } @@ -164,7 +173,7 @@ void kernfs_put_active(struct kernfs_node *kn) if (unlikely(!kn)) return; - if (kn->flags & KERNFS_LOCKDEP) + if (kernfs_lockdep(kn)) rwsem_release(&kn->dep_map, 1, _RET_IP_); v = atomic_dec_return(&kn->active); if (likely(v != KN_DEACTIVATED_BIAS)) @@ -190,25 +199,26 @@ static void kernfs_deactivate(struct kernfs_node *kn) lockdep_assert_held(&kernfs_mutex); BUG_ON(!(kn->flags & KERNFS_REMOVED)); - if (!(kernfs_type(kn) & KERNFS_ACTIVE_REF)) - return; - /* only the first invocation on @kn should deactivate it */ if (atomic_read(&kn->active) >= 0) atomic_add(KN_DEACTIVATED_BIAS, &kn->active); mutex_unlock(&kernfs_mutex); - rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); - if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS) - lock_contended(&kn->dep_map, _RET_IP_); + if (kernfs_lockdep(kn)) { + rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); + if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS) + lock_contended(&kn->dep_map, _RET_IP_); + } /* but everyone should wait for draining */ wait_event(root->deactivate_waitq, atomic_read(&kn->active) == KN_DEACTIVATED_BIAS); - lock_acquired(&kn->dep_map, _RET_IP_); - rwsem_release(&kn->dep_map, 1, _RET_IP_); + if (kernfs_lockdep(kn)) { + lock_acquired(&kn->dep_map, _RET_IP_); + rwsem_release(&kn->dep_map, 1, _RET_IP_); + } kernfs_unmap_bin_file(kn); diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 38646f6..dc4cd6c 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -35,7 +35,6 @@ enum kernfs_node_type { }; #define KERNFS_TYPE_MASK 0x000f -#define KERNFS_ACTIVE_REF KERNFS_FILE #define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK enum kernfs_node_flag { -- 1.8.5.3