Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1739309

[RFC tip/locking/lockdep v3 09/14] lockdep: Add recursive read locks into dependency graph

Show all headers | View raw

Since we have all the fundamental to handle recursive read locks, we now
add them into the dependency graph.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
 kernel/locking/lockdep.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c29b058c37b3..cae595168970 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2033,16 +2033,6 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
 	if (!check_prev_add_irq(curr, prev, next))
 		return 0;
 
-	/*
-	 * For recursive read-locks we do all the dependency checks,
-	 * but we dont store read-triggered dependencies (only
-	 * write-triggered dependencies). This ensures that only the
-	 * write-side dependencies matter, and that if for example a
-	 * write-lock never takes any other locks, then the reads are
-	 * equivalent to a NOP.
-	 */
-	if (next->read == 2 || prev->read == 2)
-		return 1;
 	/*
 	 * Is the <prev> -> <next> dependency already present?
 	 *
@@ -2164,7 +2154,7 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
 			 * Only non-recursive-read entries get new dependencies
 			 * added:
 			 */
-			if (hlock->read != 2 && hlock->check) {
+			if (hlock->check) {
 				int ret = check_prev_add(curr, hlock, next,
 							 distance, &trace, save);
 				if (!ret)
@@ -4965,7 +4955,7 @@ static inline struct lock_class *xlock_class(struct cross_lock *xlock)
  */
 static inline int depend_before(struct held_lock *hlock)
 {
-	return hlock->read != 2 && hlock->check && !hlock->trylock;
+	return hlock->check && !hlock->trylock;
 }
 
 /*
@@ -4973,7 +4963,7 @@ static inline int depend_before(struct held_lock *hlock)
  */
 static inline int depend_after(struct held_lock *hlock)
 {
-	return hlock->read != 2 && hlock->check;
+	return hlock->check;
 }
 
 /*
-- 
2.14.1

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[RFC tip/locking/lockdep v3 00/14] lockdep: Support deadlock detection for recursive read locks Boqun Feng <boqun.feng@gmail.com> - 2017-09-26 00:20 +0200
  [RFC tip/locking/lockdep v3 05/14] lockdep: Extend __bfs() to work with multiple kinds of dependencies Boqun Feng <boqun.feng@gmail.com> - 2017-09-26 00:20 +0200
  [RFC tip/locking/lockdep v3 12/14] lockdep/selftest: Unleash irq_read_recursion2 and add more Boqun Feng <boqun.feng@gmail.com> - 2017-09-26 00:20 +0200
  [RFC tip/locking/lockdep v3 02/14] lockdep: Make __bfs() visit every dependency until a match Boqun Feng <boqun.feng@gmail.com> - 2017-09-26 00:20 +0200
  [RFC tip/locking/lockdep v3 01/14] lockdep: Demagic the return value of BFS Boqun Feng <boqun.feng@gmail.com> - 2017-09-26 00:20 +0200
  [RFC tip/locking/lockdep v3 09/14] lockdep: Add recursive read locks into dependency graph Boqun Feng <boqun.feng@gmail.com> - 2017-09-26 00:20 +0200
  [RFC tip/locking/lockdep v3 04/14] lockdep: Introduce lock_list::dep Boqun Feng <boqun.feng@gmail.com> - 2017-09-26 00:20 +0200
  [RFC tip/locking/lockdep v3 06/14] lockdep: Support deadlock detection for recursive read in check_noncircular() Boqun Feng <boqun.feng@gmail.com> - 2017-09-26 00:20 +0200
  [RFC tip/locking/lockdep v3 14/14] Revert "locking/lockdep/selftests: Fix mixed read-write ABBA tests" Boqun Feng <boqun.feng@gmail.com> - 2017-09-26 00:20 +0200
  [RFC tip/locking/lockdep v3 10/14] lockdep/selftest: Add a R-L/L-W test case specific to chain cache behavior Boqun Feng <boqun.feng@gmail.com> - 2017-09-26 00:20 +0200

csiph-web