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    SubjectRe: [RFC][PATCH -mm 2/3] freezer: Introduce freezer_flags
    Hi Rafael,

    > +/*
    > + * Per task flags used by the freezer
    > + *
    > + * They should not be referred to directly outside of this file.
    > + */
    > +#define TFF_NOFREEZE 0 /* task should not be frozen */
    > +#define TFF_FREEZE 8 /* task should go to the refrigerator ASAP */
    > +#define TFF_SKIP 9 /* do not count this task as freezable */
    > +#define TFF_FROZEN 10 /* task is frozen */

    Aren't NOFREEZE and SKIP doing the same thing? One of them appears
    superfluous. I'm looking at 21-rc6-mm1 and vfork(2) seems to be its
    only user. Seeing how vfork(2) used it, can't the call to
    freezer_do_not_count() be replaced with a call to freezer_exempt()?
    Similarly, the freezer_count() after the wait_for_completion might
    just as well be a clear of the NOFREEZE bit followed by a
    try_to_freeze(). Could you please explain the rationale behind the
    SKIP flag?

    I do see that SKIP seems to be relevant for only userspace threads and
    presumably only kernel threads are allowed to set NOFREEZE, but why
    this distinction between the two?

    Also, I do have several gripes against the naming of some of these functions:

    > static inline int freezing(struct task_struct *p)

    This could be called task_should_freeze().

    > /*
    > - * Sometimes we may need to cancel the previous 'freeze' request
    > + * Cancel the previous 'freeze' request
    > */
    > static inline void do_not_freeze(struct task_struct *p)

    This definitely needs to be undo_freeze() or unfreeze().
    do_not_freeze() sounds like what freeze_exempt() does.

    > static inline void frozen_process(struct task_struct *p)

    frozen_process() sounds like what frozen() is supposed to do. This
    could instead be mark_task_frozen(), or even mark_frozen(), because
    only the current task can ever mark *itself* frozen before freezing

    > static inline void freezer_do_not_count(void)
    > static inline void freezer_count(void)

    These could be called freezer_skip() and freezer_do_not_skip(). Better
    to stick to consistent naming / terminology.

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      Last update: 2007-04-23 06:11    [W:0.021 / U:67.952 seconds]
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