From: Boqun Feng <boqun.feng@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Andrea Parri <parri.andrea@gmail.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Boqun Feng <boqun.feng@gmail.com>
Subject: [RFC tip/locking/lockdep v6 05/20] lockdep: Reduce the size of lock_list::distance
Date: Wed, 11 Apr 2018 21:50:55 +0800 [thread overview]
Message-ID: <20180411135110.9217-6-boqun.feng@gmail.com> (raw)
In-Reply-To: <20180411135110.9217-1-boqun.feng@gmail.com>
lock_list::distance is always not greater than MAX_LOCKDEP_DEPTH (which
is 48 right now), so a u16 will fit. This patch reduces the size of
lock_list::distance to save space, so that we can introduce other fields
to help detect recursive read lock deadlocks without increasing the size
of lock_list structure.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
include/linux/lockdep.h | 2 +-
kernel/locking/lockdep.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 6fc77d4dbdcd..d2af32387aaa 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -186,7 +186,7 @@ struct lock_list {
struct list_head entry;
struct lock_class *class;
struct stack_trace trace;
- int distance;
+ u16 distance;
/*
* 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 14af2327b52a..1806060c88ce 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -859,7 +859,7 @@ static struct lock_list *alloc_list_entry(void)
* Add a new dependency to the head of the list:
*/
static int add_lock_to_list(struct lock_class *this, struct list_head *head,
- unsigned long ip, int distance,
+ unsigned long ip, u16 distance,
struct stack_trace *trace)
{
struct lock_list *entry;
@@ -1996,7 +1996,7 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
goto out_bug;
for (;;) {
- int distance = curr->lockdep_depth - depth + 1;
+ u16 distance = curr->lockdep_depth - depth + 1;
hlock = curr->held_locks + depth - 1;
/*
--
2.16.2
next prev parent reply other threads:[~2018-04-11 13:50 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-11 13:50 [RFC tip/locking/lockdep v6 00/20] lockdep: Support deadlock detection for recursive read locks Boqun Feng
2018-04-11 13:50 ` [RFC tip/locking/lockdep v6 01/20] lockdep/Documention: Recursive read lock detection reasoning Boqun Feng
2018-04-15 0:38 ` Randy Dunlap
2018-04-16 6:29 ` Boqun Feng
2018-04-27 13:50 ` Boqun Feng
2018-04-11 13:50 ` [RFC tip/locking/lockdep v6 02/20] lockdep: Demagic the return value of BFS Boqun Feng
2018-04-11 13:50 ` [RFC tip/locking/lockdep v6 03/20] lockdep: Make __bfs() visit every dependency until a match Boqun Feng
2018-04-11 13:50 ` [RFC tip/locking/lockdep v6 04/20] lockdep: Redefine LOCK_*_STATE* bits Boqun Feng
2018-04-11 13:50 ` Boqun Feng [this message]
2018-04-11 13:50 ` [RFC tip/locking/lockdep v6 06/20] lockdep: Introduce lock_list::dep Boqun Feng
2018-04-11 13:50 ` [RFC tip/locking/lockdep v6 07/20] lockdep: Extend __bfs() to work with multiple types of dependencies Boqun Feng
2018-04-11 13:50 ` [RFC tip/locking/lockdep v6 08/20] lockdep: Make __bfs(.match) return bool Boqun Feng
2018-04-11 13:50 ` [RFC tip/locking/lockdep v6 09/20] lockdep: Support deadlock detection for recursive read locks in check_noncircular() Boqun Feng
2018-04-11 13:51 ` [RFC tip/locking/lockdep v6 10/20] lockdep: Adjust check_redundant() for recursive read change Boqun Feng
2018-04-11 13:51 ` [RFC tip/locking/lockdep v6 11/20] lockdep: Fix recursive read lock related safe->unsafe detection Boqun Feng
2018-04-11 13:51 ` [RFC tip/locking/lockdep v6 12/20] lockdep: Add recursive read locks into dependency graph Boqun Feng
2018-04-11 13:51 ` [RFC tip/locking/lockdep v6 13/20] lockdep/selftest: Add a R-L/L-W test case specific to chain cache behavior Boqun Feng
2018-04-11 13:51 ` [RFC tip/locking/lockdep v6 14/20] lockdep: Take read/write status in consideration when generate chainkey Boqun Feng
2018-04-11 13:51 ` [RFC tip/locking/lockdep v6 15/20] lockdep/selftest: Unleash irq_read_recursion2 and add more Boqun Feng
2018-04-11 13:51 ` [RFC tip/locking/lockdep v6 16/20] lockdep/selftest: Add more recursive read related test cases Boqun Feng
2018-04-11 13:51 ` [RFC tip/locking/lockdep v6 17/20] Revert "locking/lockdep/selftests: Fix mixed read-write ABBA tests" Boqun Feng
2018-04-11 13:51 ` [RFC tip/locking/lockdep v6 18/20] MAINTAINERS: Add myself as a LOCKING PRIMITIVES reviewer Boqun Feng
2018-04-11 13:56 ` [RFC tip/locking/lockdep v6 19/20] rcu: Equip sleepable RCU with lockdep dependency graph checks Boqun Feng
2018-04-11 18:57 ` Paul E. McKenney
2018-04-12 2:12 ` Boqun Feng
2018-04-12 9:12 ` Peter Zijlstra
2018-04-13 13:24 ` Boqun Feng
2018-04-11 13:57 ` [RFC tip/locking/lockdep v6 20/20] lockdep/selftest: Add a test case for SRCU Boqun Feng
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