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lockdep: Fix nr_unused_locks accounting 

Chris reported that commit 24d5a3bffef1 ("lockdep: Fix
usage_traceoverflow") breaks the nr_unused_locks validation code
triggered by /proc/lockdep_stats.

By fully splitting LOCK_USED and LOCK_USED_READ it becomes a bad
indicator for accounting nr_unused_locks; simplyfy by using any first
bit.

Fixes: 24d5a3bffef1 ("lockdep: Fix usage_traceoverflow")
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://lkml.kernel.org/r/20201027124834.GL2628@hirez.programming.kicks-ass.net
zero-sugar-mainline-defconfig
Peter Zijlstra 2020-10-27 13:48:34 +01:00
parent d48e385003
commit 1a39340865
1 changed files with 4 additions and 10 deletions
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14
kernel/locking/lockdep.c
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@ -4396,6 +4396,9 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
if (unlikely(hlock_class(this)->usage_mask & new_mask))
goto unlock;
if (!hlock_class(this)->usage_mask)
debug_atomic_dec(nr_unused_locks);
hlock_class(this)->usage_mask |= new_mask;
if (new_bit < LOCK_TRACE_STATES) {
@ -4403,19 +4406,10 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
return 0;
}
switch (new_bit) {
case 0 ... LOCK_USED-1:
if (new_bit < LOCK_USED) {
ret = mark_lock_irq(curr, this, new_bit);
if (!ret)
return 0;
break;
case LOCK_USED:
debug_atomic_dec(nr_unused_locks);
break;
default:
break;
}
unlock: