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From:   Yuyang Du <duyuyang@gmail.com>
Date:   Fri, 7 Jun 2019 11:21:58 +0800
Message-ID: <CAHttsrYCD1xvL6hf6dXZ_6rB2pEra0HDZ+m5n8EMQr3+5AShnQ@mail.gmail.com>
Subject: Re: "locking/lockdep: Consolidate lock usage bit initialization" is buggy
To:     Qian Cai <cai@lca.pw>
Cc:     "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Thanks for the report, but

On Fri, 7 Jun 2019 at 05:14, Qian Cai <cai@lca.pw> wrote:
>
> The linux-next commit "locking/lockdep: Consolidate lock usage bit
> initialization" [1] will always generate a warning below.

I never had such warning.

> Looking through the
> commit that when mark_irqflags() returns 1 and check = 1, it will do one less
> mark_lock() call than it used to.

The four cases:

1. When check == 1 and mark_irqflags() returns 1;
2. When check == 1 and mark_irqflags() returns 0;
3. When check == 0 and mark_irqflags() returns 1;
4. When check == 0 and mark_irqflags() returns 0;

Before and after have exactly the same code to do.