netdev - Re: [PATCH 1/2] freezer: add unsafe versions of freezable helpers

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Message-ID: <20130504130033.GB13770@amd.pavel.ucw.cz>
Date:	Sat, 4 May 2013 15:00:33 +0200
From:	Pavel Machek <pavel@....cz>
To:	Colin Cross <ccross@...roid.com>
Cc:	linux-kernel@...r.kernel.org,
	Trond Myklebust <Trond.Myklebust@...app.com>,
	Len Brown <len.brown@...el.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	"David S. Miller" <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mandeep Singh Baines <msb@...omium.org>,
	Paul Walmsley <paul@...an.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Oleg Nesterov <oleg@...hat.com>, linux-nfs@...r.kernel.org,
	linux-pm@...r.kernel.org, netdev@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, Ben Chan <benchan@...omium.org>
Subject: Re: [PATCH 1/2] freezer: add unsafe versions of freezable helpers

Hi!

> NFS calls the freezable helpers with locks held, which is unsafe
> and caused lockdep warnings when 6aa9707 "lockdep: check that no
> locks held at freeze time" was applied (reverted in dbf520a).
> Add new *_unsafe versions of the helpers that will not run the
> lockdep test when 6aa9707 is reapplied, and call them from NFS.
> 
> Signed-off-by: Colin Cross <ccross@...roid.com>

Looks mostly good.

> @@ -152,6 +169,14 @@ static inline bool freezer_should_skip(struct task_struct *p)
>  	freezer_count();						\
>  })
>  
> +/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
> +#define freezable_schedule_unsafe()					\
> +({									\
> +	freezer_do_not_count();						\
> +	schedule();							\
> +	freezer_count_unsafe();						\
> +})
> +

Make it inline function? :-). Add short explanation why it is good
idea?

> +/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
> +#define freezable_schedule_timeout_killable_unsafe(timeout)		\
> +({									\
> +	long __retval;							\
> +	freezer_do_not_count();						\
> +	__retval = schedule_timeout_killable(timeout);			\
> +	freezer_count_unsafe();						\
> +	__retval;							\
> +})

Function too?
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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