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

[Boqun Feng]

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.f...@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