The following commit has been merged into the locking/core branch of tip:
Commit-ID: 621c9dac0eea7607cb9a57cc9ba47fbcd4e644c9
Gitweb: https://git.kernel.org/tip/621c9dac0eea7607cb9a57cc9ba47fbcd4e644c9
Author: Boqun Feng <boqun.feng@xxxxxxxxx>
AuthorDate: Fri, 07 Aug 2020 15:42:31 +08:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 26 Aug 2020 12:42:06 +02:00
lockdep: Add recursive read locks into dependency graph
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@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200807074238.1632519-13-boqun.feng@xxxxxxxxx
---
kernel/locking/lockdep.c | 19 ++-----------------
1 file changed, 2 insertions(+), 17 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 6644974..b87766e 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2809,16 +2809,6 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
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?
*
* (this may occur even though this is a new chain: consider
@@ -2935,13 +2925,8 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
u16 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) {
- int ret = check_prev_add(curr, hlock, next, distance,
- &trace);
+ if (hlock->check) {
+ int ret = check_prev_add(curr, hlock, next, distance, &trace);
if (!ret)
return 0;
|