tree 935fba7ff74fe0c877982863fc752b77a2b7c4dc
parent 484354b26e80a98e702f774118dba4729eea1aff
author Yuyang Du <duyuyang@gmail.com> 1562667322 +0800
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1564904022 +0200

locking/lockdep: Fix lock used or unused stats error

[ 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>