From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f48.google.com (mail-pb0-f48.google.com [209.85.160.48]) by kanga.kvack.org (Postfix) with ESMTP id 7E46C6B0036 for ; Tue, 24 Sep 2013 18:22:52 -0400 (EDT) Received: by mail-pb0-f48.google.com with SMTP id ma3so5144852pbc.35 for ; Tue, 24 Sep 2013 15:22:52 -0700 (PDT) Subject: [PATCH v5 5/6] MCS Lock: Restructure the MCS lock defines and locking code into its own file From: Tim Chen In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Tue, 24 Sep 2013 15:22:46 -0700 Message-ID: <1380061366.3467.54.camel@schen9-DESK> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Ingo Molnar , Andrew Morton Cc: Andrea Arcangeli , Alex Shi , Andi Kleen , Michel Lespinasse , Davidlohr Bueso , Matthew R Wilcox , Dave Hansen , Peter Zijlstra , Rik van Riel , Peter Hurley , Tim Chen , linux-kernel@vger.kernel.org, linux-mm We will need the MCS lock code for doing optimistic spinning for rwsem. Extracting the MCS code from mutex.c and put into its own file allow us to reuse this code easily for rwsem. Signed-off-by: Tim Chen Signed-off-by: Davidlohr Bueso --- kernel/mutex.c | 58 ++++++------------------------------------------------- 1 files changed, 7 insertions(+), 51 deletions(-) diff --git a/kernel/mutex.c b/kernel/mutex.c index 6d647ae..1b6ba3f 100644 --- a/kernel/mutex.c +++ b/kernel/mutex.c @@ -25,6 +25,7 @@ #include #include #include +#include /* * In the DEBUG case we are using the "NULL fastpath" for mutexes, @@ -111,54 +112,9 @@ EXPORT_SYMBOL(mutex_lock); * more or less simultaneously, the spinners need to acquire a MCS lock * first before spinning on the owner field. * - * We don't inline mspin_lock() so that perf can correctly account for the - * time spent in this lock function. */ -struct mspin_node { - struct mspin_node *next ; - int locked; /* 1 if lock acquired */ -}; -#define MLOCK(mutex) ((struct mspin_node **)&((mutex)->spin_mlock)) -static noinline -void mspin_lock(struct mspin_node **lock, struct mspin_node *node) -{ - struct mspin_node *prev; - - /* Init node */ - node->locked = 0; - node->next = NULL; - - prev = xchg(lock, node); - if (likely(prev == NULL)) { - /* Lock acquired */ - node->locked = 1; - return; - } - ACCESS_ONCE(prev->next) = node; - smp_wmb(); - /* Wait until the lock holder passes the lock down */ - while (!ACCESS_ONCE(node->locked)) - arch_mutex_cpu_relax(); -} - -static void mspin_unlock(struct mspin_node **lock, struct mspin_node *node) -{ - struct mspin_node *next = ACCESS_ONCE(node->next); - - if (likely(!next)) { - /* - * Release the lock by setting it to NULL - */ - if (cmpxchg(lock, node, NULL) == node) - return; - /* Wait until the next pointer is set */ - while (!(next = ACCESS_ONCE(node->next))) - arch_mutex_cpu_relax(); - } - ACCESS_ONCE(next->locked) = 1; - smp_wmb(); -} +#define MLOCK(mutex) ((struct mcs_spin_node **)&((mutex)->spin_mlock)) /* * Mutex spinning code migrated from kernel/sched/core.c @@ -448,7 +404,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, for (;;) { struct task_struct *owner; - struct mspin_node node; + struct mcs_spin_node node; if (!__builtin_constant_p(ww_ctx == NULL) && ww_ctx->acquired > 0) { struct ww_mutex *ww; @@ -470,10 +426,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, * If there's an owner, wait for it to either * release the lock or go to sleep. */ - mspin_lock(MLOCK(lock), &node); + mcs_spin_lock(MLOCK(lock), &node); owner = ACCESS_ONCE(lock->owner); if (owner && !mutex_spin_on_owner(lock, owner)) { - mspin_unlock(MLOCK(lock), &node); + mcs_spin_unlock(MLOCK(lock), &node); goto slowpath; } @@ -488,11 +444,11 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, } mutex_set_owner(lock); - mspin_unlock(MLOCK(lock), &node); + mcs_spin_unlock(MLOCK(lock), &node); preempt_enable(); return 0; } - mspin_unlock(MLOCK(lock), &node); + mcs_spin_unlock(MLOCK(lock), &node); /* * When there's no owner, we might have preempted between the -- 1.7.4.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org