[RFC tip/locking/lockdep v5 09/17] lockdep: Add recursive read locks into dependency graph

Boqun Feng
2018-02-22T07:06:31Z

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, 1 insertion(+), 15 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index bd3eef664f9d..254f90bade54 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2038,16 +2038,6 @@ 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?
*
@@ -2151,11 +2141,7 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
int distance = curr->lockdep_depth - depth + 1;
hlock = curr->held_locks + depth - 1;

- /*
- * 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_trace);
if (!ret)
return 0;
--
2.16.1