Re: [PATCH v4] kernel.h: add comments for system_states

Mauro Carvalho Chehab
2025-09-05T12:11:48Z

Em Fri, 05 Sep 2025 12:02:37 +0300
Jani Nikula <jani.nikula@linux.intel.com> escreveu:

> On Wed, 03 Sep 2025, Randy Dunlap <rdunlap@infradead.org> wrote:
> > Provide some basic comments about the system_states and what they imply.
> > Also convert the comments to kernel-doc format.
> >
> > However, kernel-doc does not support kernel-doc notation on extern
> > struct/union/typedef/enum/etc. So I made this a DOC: block so that
> > I can use (insert) it into a Documentation (.rst) file and have it
> > look decent.
>
> The simple workaround is to separate the enum type and the variable:
>
> /**
> * kernel-doc for the enum
> */
> enum system_states {
> ...
> };
>
> /**
> * kernel-doc for the variable
> */
> extern enum system_states system_state;
>
> BR,
> Jani.
>
> >
> > Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
> > Acked-by: Rafael J. Wysocki <rafael@kernel.org> # v1
> > ---
> > v2: add Rafael's Ack.
> > v3: add Andrew
> > v4: add DOC: so that this DOC: block can be used in Documentation/
> > add Greg K-H
> > add Jon Corbet, Mauro Chehab, & linux-doc
> >
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > Cc: Pavel Machek <pavel@ucw.cz>
> > Cc: Len Brown <len.brown@intel.com>
> > Cc: linux-pm@vger.kernel.org
> > Cc: Jonathan Corbet <corbet@lwn.net>
> > Cc: linux-doc@vger.kernel.org
> > Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> > Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
> > ---
> > Documentation/driver-api/pm/devices.rst | 8 ++++++++
> > include/linux/kernel.h | 18 ++++++++++++++++--
> > 2 files changed, 24 insertions(+), 2 deletions(-)
> >
> > --- linux-next-20250819.orig/include/linux/kernel.h
> > +++ linux-next-20250819/include/linux/kernel.h
> > @@ -164,8 +164,22 @@ extern int root_mountflags;
> >
> > extern bool early_boot_irqs_disabled;
> >
> > -/*
> > - * Values used for system_state. Ordering of the states must not be changed
> > +/**
> > + * DOC: General system_states available for drivers
> > + *
> > + * enum system_states - Values used for system_state.
> > + *
> > + * * @SYSTEM_BOOTING: %0, no init needed
> > + * * @SYSTEM_SCHEDULING: system is ready for scheduling; OK to use RCU
> > + * * @SYSTEM_FREEING_INITMEM: system is freeing all of initmem; almost running
> > + * * @SYSTEM_RUNNING: system is up and running
> > + * * @SYSTEM_HALT: system entered clean system halt state
> > + * * @SYSTEM_POWER_OFF: system entered shutdown/clean power off state
> > + * * @SYSTEM_RESTART: system entered emergency power off or normal restart
> > + * * @SYSTEM_SUSPEND: system entered suspend or hibernate state
> > + *
> > + * Note:
> > + * Ordering of the states must not be changed
> > * as code checks for <, <=, >, >= STATE.
> > */
> > extern enum system_states {
> > --- linux-next-20250819.orig/Documentation/driver-api/pm/devices.rst
> > +++ linux-next-20250819/Documentation/driver-api/pm/devices.rst
> > @@ -241,6 +241,14 @@ before reactivating its class I/O queues
> > More power-aware drivers might prepare the devices for triggering system wakeup
> > events.
> >
> > +System states available for drivers
> > +-----------------------------------
> > +
> > +These system states are available for drivers to help them determine how to
> > +handle state transitions.
> > +
> > +.. kernel-doc:: include/linux/kernel.h
> > + :doc: General system_states available for drivers
> >
> > Call Sequence Guarantees
> > ------------------------
> >
>

If the problem is with "extern" before enum, fixing kdoc be
fairly trivial.

If you see:

def dump_function(self, ln, prototype):

# Prefixes that would be removed
sub_prefixes = [
...
(r"^extern +", "", 0),
...
}

for search, sub, flags in sub_prefixes:
prototype = KernRe(search, flags).sub(sub, prototype)

we need something similar to that at:
def dump_enum(self, ln, proto):

alternatively, we could use a simpler approach modifying adding a
non-group optional match for "extern". E.g:

- r = KernRe(r'enum\s+(\w*)\s*\{(.*)\}')
+ r = KernRe(r'(?:extern\s+)?enum\s+(\w*)\s*\{(.*)\}')

(untested)

Regards,
Mauro

Thanks,
Mauro