[RFC tip/locking/lockdep v3 09/14] 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, 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