Date: Sun, 5 May 2013 00:55:49 +0200
From: Pavel Machek <pavel@ucw.cz>
To: Colin Cross <ccross@android.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
        Trond Myklebust <Trond.Myklebust@netapp.com>,
        Len Brown <len.brown@intel.com>, "Rafael J. Wysocki" <rjw@sisk.pl>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        "David S. Miller" <davem@davemloft.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mandeep Singh Baines <msb@chromium.org>,
        Paul Walmsley <paul@pwsan.com>, Al Viro <viro@zeniv.linux.org.uk>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Oleg Nesterov <oleg@redhat.com>, linux-nfs@vger.kernel.org,
        Linux PM list <linux-pm@vger.kernel.org>, netdev@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Tejun Heo <tj@kernel.org>, Ben Chan <benchan@chromium.org>
Subject: Re: [PATCH 1/2] freezer: add unsafe versions of freezable helpers
Message-ID: <20130504225549.GA24276@amd.pavel.ucw.cz>
References: <1367615050-3894-1-git-send-email-ccross@android.com>
 <20130504130033.GB13770@amd.pavel.ucw.cz>
 <CAMbhsRS6+hjTmrihVzgu3Dtyp8XAhJJ4VKMj=28G6xH3H73=6Q@mail.gmail.com>
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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@android.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?
> 
> These are exact copies of the existing non-unsafe versions, except
> they call freezer_count_unsafe() instead of freezer_count().  The next
> version of my other patch stack that goes on top of this has a patch
> to convert the macros in this file to static inline functions (at
> least the ones that can be).  I'd rather not mix it in with this patch
> for ease of comparison with the existing calls.

Ok.

Acked-by: Pavel Machek <pavel@ucw.cz>

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