From: Peter Zijlstra <peterz@infradead.org>
To: Yuyang Du <duyuyang@gmail.com>
Cc: will.deacon@arm.com, mingo@kernel.org,
linux-kernel@vger.kernel.org, frederic@kernel.org, arnd@arndb.de,
cai@lca.pw
Subject: Re: [PATCH] locking/lockdep: Fix lock used or unused stats error
Date: Tue, 9 Jul 2019 15:45:42 +0200 [thread overview]
Message-ID: <20190709134542.GE3402@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190709101522.9117-1-duyuyang@gmail.com>
On Tue, Jul 09, 2019 at 06:15:22PM +0800, Yuyang Du wrote:
> 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>
Thanks!
next prev parent reply other threads:[~2019-07-09 13:45 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-09 10:15 [PATCH] locking/lockdep: Fix lock used or unused stats error Yuyang Du
2019-07-09 13:45 ` Peter Zijlstra [this message]
2019-07-13 11:14 ` [tip:locking/urgent] " tip-bot for Yuyang Du
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