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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@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200807074238.1632519-13-boqun.feng@gmail.com
This commit is contained in:
Boqun Feng 2020-08-07 15:42:31 +08:00 committed by Peter Zijlstra
parent f08e388857
commit 621c9dac0e
1 changed files with 2 additions and 17 deletions
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19
kernel/locking/lockdep.c
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@ -2808,16 +2808,6 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
if (!check_irq_usage(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?
*
@ -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;