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, linux-kernel@vger.kernel.org,
Yuyang Du <duyuyang@gmail.com>
Subject: [PATCH 15/28] locking/lockdep: Update comments on dependency search
Date: Wed, 24 Apr 2019 18:19:21 +0800 [thread overview]
Message-ID: <20190424101934.51535-16-duyuyang@gmail.com> (raw)
In-Reply-To: <20190424101934.51535-1-duyuyang@gmail.com>
The breadth-first search is implemented as flat-out non-recursive now, but
the comments are still describing it as recursive, update the comments in
that regard.
Signed-off-by: Yuyang Du <duyuyang@gmail.com>
---
kernel/locking/lockdep.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 16f524c..d153b97 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1375,6 +1375,10 @@ static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
return lock_class + offset;
}
+/*
+ * Forward- or backward-dependency search, used for both circular dependency
+ * checking and hardirq-unsafe/softirq-unsafe checking.
+ */
static int __bfs(struct lock_list *source_entry,
void *data,
int (*match)(struct lock_list *entry, void *data),
@@ -1455,12 +1459,6 @@ static inline int __bfs_backwards(struct lock_list *src_entry,
}
-/*
- * Recursive, forwards-direction lock-dependency checking, used for
- * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
- * checking.
- */
-
static void print_lock_trace(struct lock_trace *trace, unsigned int spaces)
{
unsigned long *entries = stack_trace + trace->offset;
@@ -2182,7 +2180,7 @@ static inline void inc_chains(void)
/*
* There was a chain-cache miss, and we are about to add a new dependency
- * to a previous lock. We recursively validate the following rules:
+ * to a previous lock. We validate the following rules:
*
* - would the adding of the <prev> -> <next> dependency create a
* circular dependency in the graph? [== circular deadlock]
@@ -2233,11 +2231,12 @@ static inline void inc_chains(void)
/*
* Prove that the new <prev> -> <next> dependency would not
* create a circular dependency in the graph. (We do this by
- * forward-recursing into the graph starting at <next>, and
- * checking whether we can reach <prev>.)
+ * a breadth-first search into the graph starting at <next>,
+ * which checks whether we can reach <prev>.)
*
- * We are using global variables to control the recursion, to
- * keep the stackframe size of the recursive functions low:
+ * The search is limited by the size of the circular queue (i.e.,
+ * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
+ * in the graph whose neighbours are to be checked.
*/
this.class = hlock_class(next);
this.parent = NULL;
--
1.8.3.1
next prev parent reply other threads:[~2019-04-24 10:21 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-24 10:19 [PATCH 00/28] Optimize IRQ usage checks and other small bits Yuyang Du
2019-04-24 10:19 ` [PATCH 01/28] locking/lockdep: Change all print_*() return type to void Yuyang Du
2019-04-24 10:19 ` [PATCH 02/28] locking/lockdep: Add description and explanation in lockdep design doc Yuyang Du
2019-04-25 14:01 ` Peter Zijlstra
2019-04-26 5:41 ` Yuyang Du
2019-04-24 10:19 ` [PATCH 03/28] locking/lockdep: Adjust lock usage bit character checks Yuyang Du
2019-04-24 10:19 ` [PATCH 04/28] locking/lockdep: Remove useless conditional macro Yuyang Du
2019-04-24 10:19 ` [PATCH 05/28] locking/lockdep: Print the right depth for chain key colission Yuyang Du
2019-04-24 10:19 ` [PATCH 06/28] locking/lockdep: Update obsolete struct field description Yuyang Du
2019-04-24 10:19 ` [PATCH 07/28] locking/lockdep: Use lockdep_init_task for task initiation consistently Yuyang Du
2019-04-24 10:19 ` [PATCH 08/28] locking/lockdep: Define INITIAL_CHAIN_KEY for chain keys to start with Yuyang Du
2019-04-24 10:19 ` [PATCH 09/28] locking/lockdep: Change the range of class_idx in held_lock struct Yuyang Du
2019-04-24 10:19 ` [PATCH 10/28] locking/lockdep: Remove unused argument in validate_chain() and check_deadlock() Yuyang Du
2019-04-24 10:19 ` [PATCH 11/28] locking/lockdep: Update comment Yuyang Du
2019-04-24 10:19 ` [PATCH 12/28] locking/lockdep: Change type of the element field in circular_queue Yuyang Du
2019-04-24 10:19 ` [PATCH 13/28] locking/lockdep: Change the return type of __cq_dequeue() Yuyang Du
2019-04-24 10:19 ` [PATCH 14/28] locking/lockdep: Avoid constant checks in __bfs by using offset reference Yuyang Du
2019-04-24 10:19 ` Yuyang Du [this message]
2019-04-24 10:19 ` [PATCH 16/28] locking/lockdep: Add explanation to lock usage rules in lockdep design doc Yuyang Du
2019-04-24 10:19 ` [PATCH 17/28] locking/lockdep: Remove redundant argument in check_deadlock Yuyang Du
2019-04-24 10:19 ` [PATCH 18/28] locking/lockdep: Remove unused argument in __lock_release Yuyang Du
2019-04-24 10:19 ` [PATCH 19/28] locking/lockdep: Optimize irq usage check when marking lock usage bit Yuyang Du
2019-04-25 19:32 ` Peter Zijlstra
2019-04-26 6:57 ` Yuyang Du
2019-04-30 12:11 ` Peter Zijlstra
2019-05-06 3:05 ` Yuyang Du
2019-05-06 3:42 ` Yuyang Du
2019-05-07 1:47 ` Frederic Weisbecker
2019-05-07 2:21 ` Yuyang Du
2019-04-24 10:19 ` [PATCH 20/28] locking/lockdep: Refactorize check_noncircular and check_redundant Yuyang Du
2019-04-25 19:48 ` Peter Zijlstra
2019-04-26 6:48 ` Yuyang Du
2019-04-24 10:19 ` [PATCH 21/28] locking/lockdep: Consolidate lock usage bit initialization Yuyang Du
2019-04-24 10:19 ` [PATCH 22/28] locking/lockdep: Adjust new bit cases in mark_lock Yuyang Du
2019-04-25 19:52 ` Peter Zijlstra
2019-04-26 6:47 ` Yuyang Du
2019-04-24 10:19 ` [PATCH 23/28] locking/lockdep: Update irqsafe lock bitmaps Yuyang Du
2019-04-25 19:55 ` Peter Zijlstra
2019-04-26 6:45 ` Yuyang Du
2019-04-24 10:19 ` [PATCH 24/28] locking/lockdep: Remove !dir in lock irq usage check Yuyang Du
2019-04-25 20:03 ` Peter Zijlstra
2019-04-26 7:06 ` Yuyang Du
2019-04-26 7:25 ` Boqun Feng
2019-04-30 15:35 ` Peter Zijlstra
2019-04-24 10:19 ` [PATCH 25/28] locking/lockdep: Implement new IRQ usage checking algorithm Yuyang Du
2019-04-24 10:19 ` [PATCH 26/28] locking/lockdep: Remove __bfs Yuyang Du
2019-04-25 20:06 ` Peter Zijlstra
2019-04-26 6:35 ` Yuyang Du
2019-04-24 10:19 ` [PATCH 27/28] locking/lockdep: Remove locks_before Yuyang Du
2019-04-24 10:19 ` [PATCH 28/28] locking/lockdep: Reduce lock_list_entries by half Yuyang Du
2019-04-25 18:56 ` [PATCH 00/28] Optimize IRQ usage checks and other small bits Peter Zijlstra
2019-04-26 6:59 ` Yuyang Du
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