From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
linux-mm@kvack.org, iommu@lists.linux-foundation.org,
Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Tejun Heo <tj@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Waiman Long <longman@redhat.com>
Subject: [PATCH v2 11/17] locking/rwsem: Mark rwsem.wait_lock as a terminal lock
Date: Mon, 19 Nov 2018 13:55:20 -0500 [thread overview]
Message-ID: <1542653726-5655-12-git-send-email-longman@redhat.com> (raw)
In-Reply-To: <1542653726-5655-1-git-send-email-longman@redhat.com>
The wait_lock in a rwsem is always acquired with IRQ disabled. For the
rwsem-xadd.c implementation, no other lock will be called while holding
the wait_lock. So it satisfies the condition of being a terminal lock.
By marking it as terminal, the lockdep overhead will be reduced.
Signed-off-by: Waiman Long <longman@redhat.com>
---
include/linux/rwsem.h | 11 ++++++++++-
kernel/locking/rwsem-xadd.c | 1 +
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 67dbb57..a2a2385 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -77,16 +77,25 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
# define __RWSEM_DEP_MAP_INIT(lockname)
#endif
+/*
+ * The wait_lock is marked as a terminal lock to reduce lockdep overhead
+ * when the rwsem-xadd.c is used. This is implied when
+ * CONFIG_RWSEM_SPIN_ON_OWNER is true. The rwsem-spinlock.c implementation
+ * allows calling wake_up_process() while holding the wait_lock. So it
+ * can't be marked as terminal in this case.
+ */
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
#define __RWSEM_OPT_INIT(lockname) , .osq = OSQ_LOCK_UNLOCKED, .owner = NULL
+#define __RWSEM_WAIT_LOCK_INIT(x) __RAW_TERMINAL_SPIN_LOCK_UNLOCKED(x)
#else
#define __RWSEM_OPT_INIT(lockname)
+#define __RWSEM_WAIT_LOCK_INIT(x) __RAW_SPIN_LOCK_UNLOCKED(x)
#endif
#define __RWSEM_INITIALIZER(name) \
{ __RWSEM_INIT_COUNT(name), \
.wait_list = LIST_HEAD_INIT((name).wait_list), \
- .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(name.wait_lock) \
+ .wait_lock = __RWSEM_WAIT_LOCK_INIT(name.wait_lock) \
__RWSEM_OPT_INIT(name) \
__RWSEM_DEP_MAP_INIT(name) }
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 09b1800..3dbe593 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -85,6 +85,7 @@ void __init_rwsem(struct rw_semaphore *sem, const char *name,
#endif
atomic_long_set(&sem->count, RWSEM_UNLOCKED_VALUE);
raw_spin_lock_init(&sem->wait_lock);
+ lockdep_set_terminal_class(&sem->wait_lock);
INIT_LIST_HEAD(&sem->wait_list);
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
sem->owner = NULL;
--
1.8.3.1
next prev parent reply other threads:[~2018-11-19 18:57 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-19 18:55 [PATCH v2 00/17] locking/lockdep: Add a new class of terminal locks Waiman Long
2018-11-19 18:55 ` [PATCH v2 01/17] locking/lockdep: Remove version from lock_class structure Waiman Long
2018-12-11 15:22 ` [tip:locking/core] locking/lockdep: Remove ::version " tip-bot for Waiman Long
2018-11-19 18:55 ` [PATCH v2 02/17] locking/lockdep: Rework lockdep_set_novalidate_class() Waiman Long
2018-11-19 18:55 ` [PATCH v2 03/17] locking/lockdep: Add a new terminal lock type Waiman Long
2018-12-07 9:19 ` Peter Zijlstra
2018-11-19 18:55 ` [PATCH v2 04/17] locking/lockdep: Add DEFINE_TERMINAL_SPINLOCK() and related macros Waiman Long
2018-11-19 18:55 ` [PATCH v2 05/17] printk: Mark logbuf_lock & console_owner_lock as terminal locks Waiman Long
2018-11-19 18:55 ` [PATCH v2 06/17] debugobjects: Mark pool_lock as a terminal lock Waiman Long
2018-11-19 18:55 ` [PATCH v2 07/17] debugobjects: Move printk out of db lock critical sections Waiman Long
2018-11-21 16:49 ` Waiman Long
2018-11-22 2:04 ` Sergey Senozhatsky
2018-11-22 10:16 ` Peter Zijlstra
2018-11-23 2:40 ` Sergey Senozhatsky
2018-11-23 11:48 ` Petr Mladek
2018-11-26 4:57 ` Sergey Senozhatsky
2018-11-29 13:09 ` Petr Mladek
2018-11-22 16:02 ` Petr Mladek
2018-11-22 20:29 ` Waiman Long
2018-11-23 11:36 ` Petr Mladek
2018-11-22 19:57 ` Waiman Long
2018-11-23 2:35 ` Sergey Senozhatsky
2018-11-23 11:20 ` Petr Mladek
2018-12-07 9:21 ` Peter Zijlstra
2018-11-19 18:55 ` [PATCH v2 08/17] locking/lockdep: Add support for nestable terminal locks Waiman Long
2018-12-07 9:22 ` Peter Zijlstra
2018-12-07 9:52 ` Peter Zijlstra
2018-11-19 18:55 ` [PATCH v2 09/17] debugobjects: Make object hash locks " Waiman Long
2018-11-22 15:33 ` Petr Mladek
2018-11-22 20:17 ` Waiman Long
2018-11-23 9:29 ` Petr Mladek
2018-12-07 9:47 ` Peter Zijlstra
2018-11-19 18:55 ` [PATCH v2 10/17] lib/stackdepot: Make depot_lock a terminal spinlock Waiman Long
2018-11-19 18:55 ` Waiman Long [this message]
2018-11-19 18:55 ` [PATCH v2 12/17] cgroup: Mark the rstat percpu lock as terminal Waiman Long
2018-11-19 18:55 ` [PATCH v2 13/17] mm/kasan: Make quarantine_lock a terminal lock Waiman Long
2018-11-19 18:55 ` [PATCH v2 14/17] dma-debug: Mark free_entries_lock as terminal Waiman Long
2018-11-19 18:55 ` [PATCH v2 15/17] kernfs: Mark kernfs_open_node_lock as terminal lock Waiman Long
2018-11-19 18:55 ` [PATCH v2 16/17] delay_acct: Mark task's delays->lock as terminal spinlock Waiman Long
2018-11-19 18:55 ` [PATCH v2 17/17] locking/lockdep: Check raw/non-raw locking conflicts Waiman Long
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