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    Subject[ 08/23] [Suspend2] New freezer explanation for kernel/power/process.c
    Date

    Modify kernel/power/process.c header to describe how the new freezer
    implementation works.

    Signed-off-by: Nigel Cunningham <nigel@suspend2.net>

    kernel/power/process.c | 26 +++++++++++++++++++++++---
    1 files changed, 23 insertions(+), 3 deletions(-)

    diff --git a/kernel/power/process.c b/kernel/power/process.c
    index a788186..6da0445 100644
    --- a/kernel/power/process.c
    +++ b/kernel/power/process.c
    @@ -1,8 +1,28 @@
    /*
    - * drivers/power/process.c - Functions for starting/stopping processes on
    - * suspend transitions.
    + * kernel/power/process.c
    *
    - * Originally from swsusp.
    + * Copyright (C) 1998-2001 Gabor Kuti <seasons@fornax.hu>
    + * Copyright (C) 1998,2001,2002 Pavel Machek <pavel@suse.cz>
    + * Copyright (C) 2002-2003 Florent Chabaud <fchabaud@free.fr>
    + * Copyright (C) 2002-2006 Nigel Cunningham <nigel@suspend2.net>
    + *
    + * This file is released under the GPLv2.
    + *
    + * It contains the routines used to freeze processes during a suspend
    + * cycle (or perhaps in future, a process migration).
    + *
    + * When quiescing the whole system, one process initiates this
    + * functionality by calling freeze_processes(). First, userspace
    + * is frozen. Then bdevs for mounted filesystems are frozen so
    + * as to ensure pending I/O is flushed and stopped. Finally,
    + * kernel threads which are no marked as unfreezeable (perhaps
    + * because they're needed for doing I/O) are frozen. Splitting
    + * kernel threads from userspace also improves reliability,
    + * because it ensures that a userspace thread doesn't deadlock,
    + * waiting for a kernel thread that has already been frozen to
    + * process some request, and because it stops the cause of most
    + * work for kernel threads (ie userspace), allowing those thread
    + * to complete their work more quickly.
    */


    --
    Nigel Cunningham nigel at suspend2 dot net
    -
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