Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756059AbdC2Ku5 (ORCPT ); Wed, 29 Mar 2017 06:50:57 -0400 Received: from merlin.infradead.org ([205.233.59.134]:34238 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932356AbdC2Ktd (ORCPT ); Wed, 29 Mar 2017 06:49:33 -0400 Date: Wed, 29 Mar 2017 12:49:07 +0200 From: Peter Zijlstra To: Davidlohr Bueso Cc: mingo@kernel.org, akpm@linux-foundation.org, jack@suse.cz, kirill.shutemov@linux.intel.com, mhocko@suse.com, mgorman@techsingularity.net, linux-kernel@vger.kernel.org, Davidlohr Bueso Subject: Re: [PATCH 1/5] locking: Introduce range reader/writer lock Message-ID: <20170329104907.2ks5uoykq2mqmwm3@hirez.programming.kicks-ass.net> References: <1488863010-13028-1-git-send-email-dave@stgolabs.net> <1488863010-13028-2-git-send-email-dave@stgolabs.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1488863010-13028-2-git-send-email-dave@stgolabs.net> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1165 Lines: 39 On Mon, Mar 06, 2017 at 09:03:26PM -0800, Davidlohr Bueso wrote: > +static __always_inline int > +__range_read_lock_common(struct range_rwlock_tree *tree, > + struct range_rwlock *lock, long state) > +{ > + struct interval_tree_node *node; > + unsigned long flags; > + > + spin_lock_irqsave(&tree->lock, flags); > + lock->reader = true; > + > + if (!__range_intersects_intree(tree, lock)) > + goto insert; > + > + node = interval_tree_iter_first(&tree->root, lock->node.start, > + lock->node.last); > + while (node) { > + struct range_rwlock *blocked_lock; > + blocked_lock = range_entry(node, struct range_rwlock, node); > + > + if (!blocked_lock->reader) > + lock->blocking_ranges++; > + node = interval_tree_iter_next(node, lock->node.start, > + lock->node.last); > + } > +insert: > + __range_tree_insert(tree, lock); > + > + lock->task = current; > + spin_unlock_irqrestore(&tree->lock, flags); > + > + return wait_for_ranges(tree, lock, state); > +} Another thing; this implementation lacks lockdep annotations and has 0 other debugging features. Is there something that makes the normal rwsem lockdep annotation not work for this?