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From: Yuyang Du <duyuyang@gmail.com>
To: peterz@infradead.org, will.deacon@arm.com, mingo@kernel.org
Cc: bvanassche@acm.org, ming.lei@redhat.com, frederic@kernel.org,
	tglx@linutronix.de, boqun.feng@gmail.com,
	linux-kernel@vger.kernel.org, Yuyang Du <duyuyang@gmail.com>
Subject: [PATCH 02/17] locking/lockdep: Add read-write type for dependency
Date: Mon, 13 May 2019 17:11:48 +0800	[thread overview]
Message-ID: <20190513091203.7299-3-duyuyang@gmail.com> (raw)
In-Reply-To: <20190513091203.7299-1-duyuyang@gmail.com>

Direct dependency needs to keep track of its locks' read-write types.  A
union field is added to lock_list struct so the type is stored there as
this:

	lock_type[1] (u16), lock_type[0] (u16)

			or:

	dep_type (int)

where value:

 0: exclusive / write
 1: read
 2: recursive read

Note that (int) dep_type value may vary with different architectural
endianness, so use helpers to operate on these types.

Signed-off-by: Yuyang Du <duyuyang@gmail.com>
---
 include/linux/lockdep.h            | 12 ++++++++++++
 kernel/locking/lockdep.c           | 34 +++++++++++++++++++++++++++++++---
 kernel/locking/lockdep_internals.h |  3 +++
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 441288c..6aa9af2 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -195,6 +195,18 @@ struct lock_list {
 	struct lock_class		*links_to;
 	struct lock_trace		trace;
 	int				distance;
+	/*
+	 * This field keeps track of the read-write type of this dependency.
+	 *
+	 * With L1 -> L2:
+	 *
+	 * lock_type[0] stores the type of L1, while lock_type[1] stores the
+	 * type of L2.
+	 */
+	union {
+		int	dep_type;
+		u16	lock_type[2];
+	};
 
 	/*
 	 * The parent field is used to implement breadth-first search, and the
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index e9eafcf..4091002 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1225,7 +1225,7 @@ static struct lock_list *alloc_list_entry(void)
 static int add_lock_to_list(struct lock_class *this,
 			    struct lock_class *links_to, struct list_head *head,
 			    unsigned long ip, int distance,
-			    struct lock_trace *trace)
+			    struct lock_trace *trace, int dep_type)
 {
 	struct lock_list *entry;
 	/*
@@ -1240,6 +1240,8 @@ static int add_lock_to_list(struct lock_class *this,
 	entry->links_to = links_to;
 	entry->distance = distance;
 	entry->trace = *trace;
+	entry->dep_type = dep_type;
+
 	/*
 	 * Both allocation and removal are done under the graph lock; but
 	 * iteration is under RCU-sched; see look_up_lock_class() and
@@ -1677,6 +1679,30 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class)
 	return ret;
 }
 
+static inline int get_dep_type(struct held_lock *lock1, struct held_lock *lock2)
+{
+	/*
+	 * With dependency lock1 -> lock2:
+	 *
+	 * lock_type[0] is lock1, while lock_type[1] is lock2.
+	 *
+	 * Avoid architectural endianness difference composing dep_type.
+	 */
+	u16 type[2] = { lock1->read, lock2->read };
+
+	return *(int *)type;
+}
+
+static inline int get_lock_type1(struct lock_list *lock)
+{
+	return lock->lock_type[0];
+}
+
+static inline int get_lock_type2(struct lock_list *lock)
+{
+	return lock->lock_type[1];
+}
+
 /*
  * Check that the dependency graph starting at <src> can lead to
  * <target> or not. Print an error and return 0 if it does.
@@ -2446,14 +2472,16 @@ static inline void inc_chains(void)
 	 */
 	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
 			       &hlock_class(prev)->locks_after,
-			       next->acquire_ip, distance, trace);
+			       next->acquire_ip, distance, trace,
+			       get_dep_type(prev, next));
 
 	if (!ret)
 		return 0;
 
 	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
 			       &hlock_class(next)->locks_before,
-			       next->acquire_ip, distance, trace);
+			       next->acquire_ip, distance, trace,
+			       get_dep_type(next, prev));
 	if (!ret)
 		return 0;
 
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index 150ec3f..c287bcb 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -26,6 +26,9 @@ enum lock_usage_bit {
 #define LOCK_USAGE_DIR_MASK  2
 #define LOCK_USAGE_STATE_MASK (~(LOCK_USAGE_READ_MASK | LOCK_USAGE_DIR_MASK))
 
+#define LOCK_TYPE_BITS	16
+#define LOCK_TYPE_MASK	0xFFFF
+
 /*
  * Usage-state bitmasks:
  */
-- 
1.8.3.1


  parent reply	other threads:[~2019-05-13  9:13 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-13  9:11 [PATCH 00/17] Support for read-write lock deadlock detection Yuyang Du
2019-05-13  9:11 ` [PATCH 01/17] locking/lockdep: Add lock type enum to explicitly specify read or write locks Yuyang Du
2019-05-13 11:45   ` Peter Zijlstra
2019-05-14  1:31     ` Yuyang Du
2019-05-14 12:04       ` Peter Zijlstra
2019-05-13  9:11 ` Yuyang Du [this message]
2019-05-13  9:11 ` [PATCH 03/17] locking/lockdep: Add helper functions to operate on the searched path Yuyang Du
2019-05-13  9:11 ` [PATCH 04/17] locking/lockdep: Update direct dependency's read-write type if it exists Yuyang Du
2019-05-13  9:11 ` [PATCH 05/17] locking/lockdep: Rename deadlock check functions Yuyang Du
2019-05-13  9:11 ` [PATCH 06/17] locking/lockdep: Adjust BFS algorithm to support multiple matches Yuyang Du
2019-05-13  9:11 ` [PATCH 07/17] locking/lockdep: Introduce mark_lock_unaccessed() Yuyang Du
2019-05-13  9:11 ` [PATCH 08/17] locking/lockdep: Introduce chain_hlocks_type for held lock's read-write type Yuyang Du
2019-05-13  9:11 ` [PATCH 09/17] locking/lockdep: Hash held lock's read-write type into chain key Yuyang Du
2019-05-13  9:11 ` [PATCH 10/17] locking/lockdep: Support read-write lock's deadlock detection Yuyang Du
2019-05-13  9:11 ` [PATCH 11/17] locking/lockdep: Adjust lockdep selftest cases Yuyang Du
2019-05-13  9:11 ` [PATCH 12/17] locking/lockdep: Remove useless lock type assignment Yuyang Du
2019-05-13  9:11 ` [PATCH 13/17] locking/lockdep: Add nest lock type Yuyang Du
2019-05-13  9:12 ` [PATCH 14/17] locking/lockdep: Support recursive read locks Yuyang Du
2019-05-13  9:12 ` [PATCH 15/17] locking/lockdep: Adjust selftest case for recursive read lock Yuyang Du
2019-05-13  9:12 ` [PATCH 16/17] locking/lockdep: Add more lockdep selftest cases Yuyang Du
2019-05-13  9:12 ` [PATCH 17/17] locking/lockdep: Remove irq-safe to irq-unsafe read check Yuyang Du
2019-05-13  9:17 ` [PATCH 00/17] Support for read-write lock deadlock detection Yuyang Du

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