Re: [PATCH v4 15/15] lockdep: Crossrelease feature documentation

From	Boqun Feng <boqun.feng@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 15/15] lockdep: Crossrelease feature documentation
Date	2017-01-18 07:50 +0100
Message-ID	<t0See-D1-5@gated-at.bofh.it> (permalink)
References	<sMlLb-7BJ-3@gated-at.bofh.it> <sMlLb-7BJ-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, Dec 09, 2016 at 02:12:11PM +0900, Byungchul Park wrote:
[...]
> +Example 1:
> +
> +   CONTEXT X		   CONTEXT Y
> +   ---------		   ---------
> +   mutext_lock A
> +			   lock_page B
> +   lock_page B
> +			   mutext_lock A /* DEADLOCK */

s/mutext_lock/mutex_lock

> +   unlock_page B
> +			   mutext_unlock A
> +   mutex_unlock A
> +			   unlock_page B
> +
> +   where A is a lock class and B is a page lock.
> +
> +No, we cannot.
> +
> +Example 2:
> +
> +   CONTEXT X	   CONTEXT Y	   CONTEXT Z
> +   ---------	   ---------	   ----------
> +		   mutex_lock A
> +   lock_page B
> +		   lock_page B
> +				   mutext_lock A /* DEADLOCK */
> +				   mutext_unlock A

Ditto.

> +				   unlock_page B held by X
> +		   unlock_page B
> +		   mutex_unlock A
> +
> +   where A is a lock class and B is a page lock.
> +
> +No, we cannot.
> +
> +Example 3:
> +
> +   CONTEXT X		   CONTEXT Y
> +   ---------		   ---------
> +			   mutex_lock A
> +   mutex_lock A
> +   mutex_unlock A
> +			   wait_for_complete B /* DEADLOCK */

I think this part better be:

   CONTEXT X		   CONTEXT Y
   ---------		   ---------
   			   mutex_lock A
   mutex_lock A
   			   wait_for_complete B /* DEADLOCK */
   mutex_unlock A

, right? Because Y triggers DEADLOCK before X could run mutex_unlock().

Regards,
Boqun

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Re: [PATCH v4 15/15] lockdep: Crossrelease feature documentation Boqun Feng <boqun.feng@gmail.com> - 2017-01-18 07:50 +0100
  Re: [PATCH v4 15/15] lockdep: Crossrelease feature documentation Peter Zijlstra <peterz@infradead.org> - 2017-01-18 12:10 +0100
    Re: [PATCH v4 15/15] lockdep: Crossrelease feature documentation Byungchul Park <byungchul.park@lge.com> - 2017-01-18 13:00 +0100
      RE: [PATCH v4 15/15] lockdep: Crossrelease feature documentation "byungchul.park" <byungchul.park@lge.com> - 2017-01-18 13:20 +0100
        Re: [PATCH v4 15/15] lockdep: Crossrelease feature documentation Peter Zijlstra <peterz@infradead.org> - 2017-01-18 15:20 +0100
          Re: [PATCH v4 15/15] lockdep: Crossrelease feature documentation Byungchul Park <byungchul.park@lge.com> - 2017-01-19 03:20 +0100
      Re: [PATCH v4 15/15] lockdep: Crossrelease feature documentation Peter Zijlstra <peterz@infradead.org> - 2017-01-18 13:40 +0100
        RE: [PATCH v4 15/15] lockdep: Crossrelease feature documentation "byungchul.park" <byungchul.park@lge.com> - 2017-01-18 14:00 +0100
  Re: [PATCH v4 15/15] lockdep: Crossrelease feature documentation Byungchul Park <byungchul.park@lge.com> - 2017-01-18 12:20 +0100

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