From: Yuyang Du duyuyang@gmail.com
[ Upstream commit 68d41d8c94a31dfb8233ab90b9baf41a2ed2da68 ]
The stats variable nr_unused_locks is incremented every time a new lock class is register and decremented when the lock is first used in __lock_acquire(). And after all, it is shown and checked in lockdep_stats.
However, under configurations that either CONFIG_TRACE_IRQFLAGS or CONFIG_PROVE_LOCKING is not defined:
The commit:
091806515124b20 ("locking/lockdep: Consolidate lock usage bit initialization")
missed marking the LOCK_USED flag at IRQ usage initialization because as mark_usage() is not called. And the commit:
886532aee3cd42d ("locking/lockdep: Move mark_lock() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING")
further made mark_lock() not defined such that the LOCK_USED cannot be marked at all when the lock is first acquired.
As a result, we fix this by not showing and checking the stats under such configurations for lockdep_stats.
Reported-by: Qian Cai cai@lca.pw Signed-off-by: Yuyang Du duyuyang@gmail.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Cc: Andrew Morton akpm@linux-foundation.org Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Paul E. McKenney paulmck@linux.vnet.ibm.com Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Will Deacon will.deacon@arm.com Cc: arnd@arndb.de Cc: frederic@kernel.org Link: https://lkml.kernel.org/r/20190709101522.9117-1-duyuyang@gmail.com Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/locking/lockdep_proc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c index 3dd980dfba2d..6cf288eef670 100644 --- a/kernel/locking/lockdep_proc.c +++ b/kernel/locking/lockdep_proc.c @@ -210,6 +210,7 @@ static int lockdep_stats_show(struct seq_file *m, void *v) nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0, sum_forward_deps = 0;
+#ifdef CONFIG_PROVE_LOCKING list_for_each_entry(class, &all_lock_classes, lock_entry) {
if (class->usage_mask == 0) @@ -241,12 +242,12 @@ static int lockdep_stats_show(struct seq_file *m, void *v) if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ) nr_hardirq_read_unsafe++;
-#ifdef CONFIG_PROVE_LOCKING sum_forward_deps += lockdep_count_forward_deps(class); -#endif } #ifdef CONFIG_DEBUG_LOCKDEP DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused); +#endif + #endif seq_printf(m, " lock-classes: %11lu [max: %lu]\n", nr_lock_classes, MAX_LOCKDEP_KEYS);