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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT 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 09084C282CE for ; Tue, 4 Jun 2019 08:53:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D52C7245C1 for ; Tue, 4 Jun 2019 08:53:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Ptqdkyup" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727028AbfFDIxE (ORCPT ); Tue, 4 Jun 2019 04:53:04 -0400 Received: from merlin.infradead.org ([205.233.59.134]:34054 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726793AbfFDIxC (ORCPT ); Tue, 4 Jun 2019 04:53:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=1+roFI1LTutUa2nnj4FjSsN9h8+OYYtCkAaKCsM63A0=; b=Ptqdkyup7y9RWMBq3RYU+raqs l0dvw8bphckKX200JwjeVOtFwGQ5cku8Hx6R/SysXN//M0+jpKJPAFN+y95snltcASslMkoPKZK3X DN9WP/4KgHVnu7QMeZncQlJf2bHGbqvDyCsvvk7J6rtFAESaGC8GUXy1rNKP0DGcZwKEdgaz4nB+j zEd6VoDQu7syb9MKTLNKSpApQUt8Vv8KiOWd4rGSVphdlSMIQNyuy+nEVL796ZD50ij2gf5I6P/y9 v1aezeCSLKQQwBBK0JlSkjzdENa3S5/IRPQ9PAbg5R5wOR1xhSGb0IijhhrNRg9d7dtuflK8dh72u gh60fLvtA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hY5BQ-0002sZ-Pc; Tue, 04 Jun 2019 08:52:40 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 23E122083F71A; Tue, 4 Jun 2019 10:52:38 +0200 (CEST) Date: Tue, 4 Jun 2019 10:52:38 +0200 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , Thomas Gleixner , Borislav Petkov , "H. Peter Anvin" , linux-kernel@vger.kernel.org, x86@kernel.org, Davidlohr Bueso , Linus Torvalds , Tim Chen , huang ying Subject: Re: [PATCH v8 13/19] locking/rwsem: Make rwsem->owner an atomic_long_t Message-ID: <20190604085238.GF3402@hirez.programming.kicks-ass.net> References: <20190520205918.22251-1-longman@redhat.com> <20190520205918.22251-14-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190520205918.22251-14-longman@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 20, 2019 at 04:59:12PM -0400, Waiman Long wrote: > +static inline struct task_struct *rwsem_read_owner(struct rw_semaphore *sem) > +{ > + return (struct task_struct *)(atomic_long_read(&sem->owner) & > + ~RWSEM_OWNER_FLAGS_MASK); > +} > + > +/* > + * Return the real task structure pointer of the owner and the embedded > + * flags in the owner. pflags must be non-NULL. > + */ > +static inline struct task_struct * > +rwsem_read_owner_flags(struct rw_semaphore *sem, long *pflags) > +{ > + long owner = atomic_long_read(&sem->owner); > + > + *pflags = owner & RWSEM_OWNER_FLAGS_MASK; > + return (struct task_struct *)(owner & ~RWSEM_OWNER_FLAGS_MASK); > +} I got confused by the 'read' part in those nanes, I initially thought they paired with rwsem_set_reader_owned(). So I've done 's/rwsem_read_owner/rwsem_owner/g on it. --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -194,10 +194,10 @@ static inline void rwsem_clear_reader_ow /* * Return just the real task structure pointer of the owner */ -static inline struct task_struct *rwsem_read_owner(struct rw_semaphore *sem) +static inline struct task_struct *rwsem_owner(struct rw_semaphore *sem) { - return (struct task_struct *)(atomic_long_read(&sem->owner) & - ~RWSEM_OWNER_FLAGS_MASK); + return (struct task_struct *) + (atomic_long_read(&sem->owner) & ~RWSEM_OWNER_FLAGS_MASK); } /* @@ -205,7 +205,7 @@ static inline struct task_struct *rwsem_ * flags in the owner. pflags must be non-NULL. */ static inline struct task_struct * -rwsem_read_owner_flags(struct rw_semaphore *sem, long *pflags) +rwsem_owner_flags(struct rw_semaphore *sem, long *pflags) { long owner = atomic_long_read(&sem->owner); @@ -561,7 +561,7 @@ static inline bool rwsem_can_spin_on_own preempt_disable(); rcu_read_lock(); - owner = rwsem_read_owner_flags(sem, &flags); + owner = rwsem_owner_flags(sem, &flags); if ((flags & RWSEM_NONSPINNABLE) || (owner && !owner_on_cpu(owner))) ret = false; rcu_read_unlock(); @@ -590,8 +590,8 @@ enum owner_state { }; #define OWNER_SPINNABLE (OWNER_NULL | OWNER_WRITER) -static inline enum owner_state rwsem_owner_state(struct task_struct *owner, - long flags) +static inline enum owner_state +rwsem_owner_state(struct task_struct *owner, long flags) { if (flags & RWSEM_NONSPINNABLE) return OWNER_NONSPINNABLE; @@ -608,7 +608,7 @@ static noinline enum owner_state rwsem_s long flags, new_flags; enum owner_state state; - owner = rwsem_read_owner_flags(sem, &flags); + owner = rwsem_owner_flags(sem, &flags); state = rwsem_owner_state(owner, flags); if (state != OWNER_WRITER) return state; @@ -620,7 +620,7 @@ static noinline enum owner_state rwsem_s break; } - new = rwsem_read_owner_flags(sem, &new_flags); + new = rwsem_owner_flags(sem, &new_flags); if ((new != owner) || (new_flags != flags)) { state = rwsem_owner_state(new, new_flags); break; @@ -1139,7 +1139,7 @@ static inline void __up_write(struct rw_ * sem->owner may differ from current if the ownership is transferred * to an anonymous writer by setting the RWSEM_NONSPINNABLE bits. */ - DEBUG_RWSEMS_WARN_ON((rwsem_read_owner(sem) != current) && + DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE), sem); rwsem_clear_owner(sem); tmp = atomic_long_fetch_add_release(-RWSEM_WRITER_LOCKED, &sem->count); @@ -1161,7 +1161,7 @@ static inline void __downgrade_write(str * read-locked region is ok to be re-ordered into the * write side. As such, rely on RELEASE semantics. */ - DEBUG_RWSEMS_WARN_ON(rwsem_read_owner(sem) != current, sem); + DEBUG_RWSEMS_WARN_ON(rwsem_owner(sem) != current, sem); tmp = atomic_long_fetch_add_release( -RWSEM_WRITER_LOCKED+RWSEM_READER_BIAS, &sem->count); rwsem_set_reader_owned(sem);