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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, 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: [RFC PATCH 07/12] locking/lockdep: Add support for nested terminal locks
Date: Thu,  8 Nov 2018 15:34:23 -0500	[thread overview]
Message-ID: <1541709268-3766-8-git-send-email-longman@redhat.com> (raw)
In-Reply-To: <1541709268-3766-1-git-send-email-longman@redhat.com>

There are use cases where we want to allow 2-level nesting of one
terminal lock underneath another one. So the terminal lock type is now
extended to support a new nested terminal lock where it can allow the
acquisition of another regular terminal lock underneath it.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 include/linux/lockdep.h            |  9 ++++++++-
 kernel/locking/lockdep.c           | 15 +++++++++++++--
 kernel/locking/lockdep_internals.h |  2 +-
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index c5ff8c5..ed4d177 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -147,12 +147,16 @@ struct lock_class_stats {
  * 1) LOCKDEP_FLAG_NOVALIDATE: No full validation, just simple checks.
  * 2) LOCKDEP_FLAG_TERMINAL: This is a terminal lock where lock/unlock on
  *    another lock within its critical section is not allowed.
+ * 3) LOCKDEP_FLAG_TERMINAL_NESTED: This is a terminal lock that allows
+ *    one more regular terminal lock to be nested underneath it.
  */
 #define LOCKDEP_FLAG_NOVALIDATE 	(1 << 0)
 #define LOCKDEP_FLAG_TERMINAL		(1 << 1)
+#define LOCKDEP_FLAG_TERMINAL_NESTED	(1 << 2)
 
 #define LOCKDEP_NOCHECK_FLAGS		(LOCKDEP_FLAG_NOVALIDATE |\
-					 LOCKDEP_FLAG_TERMINAL)
+					 LOCKDEP_FLAG_TERMINAL   |\
+					 LOCKDEP_FLAG_TERMINAL_NESTED)
 
 /*
  * Map the lock object (the lock instance) to the lock-class object.
@@ -314,6 +318,8 @@ extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 	do { (lock)->dep_map.flags |= LOCKDEP_FLAG_NOVALIDATE; } while (0)
 #define lockdep_set_terminal_class(lock) \
 	do { (lock)->dep_map.flags |= LOCKDEP_FLAG_TERMINAL; } while (0)
+#define lockdep_set_terminal_nested_class(lock) \
+	do { (lock)->dep_map.flags |= LOCKDEP_FLAG_TERMINAL_NESTED; } while (0)
 
 /*
  * Compare locking classes
@@ -431,6 +437,7 @@ static inline void lockdep_on(void)
 
 #define lockdep_set_novalidate_class(lock)	do { } while (0)
 #define lockdep_set_terminal_class(lock)	do { } while (0)
+#define lockdep_set_terminal_nested_class(lock)	do { } while (0)
 
 /*
  * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 02631a0..2b75613 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3268,13 +3268,24 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 	class_idx = class - lock_classes + 1;
 
 	if (depth) {
+		int prev_type;
+
 		hlock = curr->held_locks + depth - 1;
 
 		/*
-		 * Warn if the previous lock is a terminal lock.
+		 * Warn if the previous lock is a terminal lock or the
+		 * previous lock is a nested terminal lock and the current
+		 * one isn't a regular terminal lock.
 		 */
-		if (DEBUG_LOCKS_WARN_ON(hlock_is_terminal(hlock)))
+		prev_type = hlock_is_terminal(hlock);
+		if (DEBUG_LOCKS_WARN_ON((prev_type == LOCKDEP_FLAG_TERMINAL) ||
+			((prev_type == LOCKDEP_FLAG_TERMINAL_NESTED) &&
+			 (flags_is_terminal(class->flags) !=
+				LOCKDEP_FLAG_TERMINAL)))) {
+			pr_warn("Terminal lock error: prev lock = %s, curr lock = %s\n",
+				hlock->instance->name, class->name);
 			return 0;
+		}
 
 		if (hlock->class_idx == class_idx && nest_lock) {
 			if (hlock->references) {
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index 271fba8..abe646a 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -215,5 +215,5 @@ static inline unsigned long debug_class_ops_read(struct lock_class *class)
 
 static inline unsigned int flags_is_terminal(unsigned int flags)
 {
-	return flags & LOCKDEP_FLAG_TERMINAL;
+	return flags & (LOCKDEP_FLAG_TERMINAL|LOCKDEP_FLAG_TERMINAL_NESTED);
 }
-- 
1.8.3.1


  parent reply	other threads:[~2018-11-08 20:35 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-08 20:34 [RFC PATCH 00/12] locking/lockdep: Add a new class of " Waiman Long
2018-11-08 20:34 ` [RFC PATCH 01/12] locking/lockdep: Rework lockdep_set_novalidate_class() Waiman Long
2018-11-10 14:14   ` Peter Zijlstra
2018-11-11  0:26     ` Waiman Long
2018-11-11  1:28       ` Peter Zijlstra
2018-11-08 20:34 ` [RFC PATCH 02/12] locking/lockdep: Add a new terminal lock type Waiman Long
2018-11-10 14:17   ` Peter Zijlstra
2018-11-11  0:28     ` Waiman Long
2018-11-08 20:34 ` [RFC PATCH 03/12] locking/lockdep: Add DEFINE_TERMINAL_SPINLOCK() and related macros Waiman Long
2018-11-08 20:34 ` [RFC PATCH 04/12] printk: Make logbuf_lock a terminal lock Waiman Long
2018-11-08 20:34 ` [RFC PATCH 05/12] debugobjects: Mark pool_lock as " Waiman Long
2018-11-08 20:34 ` [RFC PATCH 06/12] debugobjects: Move printk out of db lock critical sections Waiman Long
2018-11-08 20:34 ` Waiman Long [this message]
2018-11-10 14:20   ` [RFC PATCH 07/12] locking/lockdep: Add support for nested terminal locks Peter Zijlstra
2018-11-11  0:30     ` Waiman Long
2018-11-11  1:30       ` Peter Zijlstra
2018-11-08 20:34 ` [RFC PATCH 08/12] debugobjects: Make object hash locks " Waiman Long
2018-11-08 20:34 ` [RFC PATCH 09/12] lib/stackdepot: Make depot_lock a terminal spinlock Waiman Long
2018-11-08 20:34 ` [RFC PATCH 10/12] locking/rwsem: Mark rwsem.wait_lock as a terminal lock Waiman Long
2018-11-08 20:34 ` [RFC PATCH 11/12] cgroup: Mark the rstat percpu lock as terminal Waiman Long
2018-11-08 20:34 ` [RFC PATCH 12/12] mm/kasan: Make quarantine_lock a terminal lock Waiman Long
2018-11-09  8:04 ` [RFC PATCH 00/12] locking/lockdep: Add a new class of terminal locks Ingo Molnar
2018-11-09 15:48   ` Waiman Long
2018-11-12  5:15     ` Ingo Molnar
2018-11-10 14:10   ` Peter Zijlstra
2018-11-10 23:35     ` Waiman Long
2018-11-12  5:10       ` Ingo Molnar
2018-11-12  5:53         ` Josh Poimboeuf
2018-11-12  6:30           ` Ingo Molnar
2018-11-12 22:22             ` Josh Poimboeuf
2018-11-12 22:56               ` Waiman Long

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