[PATCH v3 00/16] timers: Cleanup delay/sleep related mess

[PATCH v3 00/16] timers: Cleanup delay/sleep related mess

[Anna-Maria Behnsen]

Hi,

a question about which sleeping function should be used in acpi_os_sleep()
started a discussion and examination about the existing documentation and
implementation of functions which insert a sleep/delay.

The result of the discussion was, that the documentation is outdated and
the implemented fsleep() reflects the outdated documentation but doesn't
help to reflect reality which in turns leads to the queue which covers the
following things:

- Split out all timeout and sleep related functions from hrtimer.c and timer.c
  into a separate file

- Update function descriptions of sleep related functions

- Change fsleep() to reflect reality

- Rework all comments or users which obviously rely on the outdated
  documentation as they reference "Documentation/timers/timers-howto.rst"

- Update the outdated documentation and move it into a file with a self
  explaining file name (as there are no more references)

- Remove checkpatch checks which also rely on the outdated documentation

The queue is available here:

  git://git.kernel.org/pub/scm/linux/kernel/git/anna-maria/linux-devel.git timers/misc

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
---
Changes in v3:
- Add review remarks
- Split checkpatch patch: 1. Remove links to outdated documentation,
  2. Remove checks in checkpatch which rely on outdated documentation
- Link to v2: https://lore.kernel.org/r/20240911-devel-anna-maria-b4-timers-flseep-v2-0-b0d3f33ccfe0@linutronix.de

Changes in v2:
- change udelay() and ndelay() as suggested by Thomas
- Update some formatting in the new sleep_timeout.c file
- minor typo changes and other small review remarks

Thanks,

        Anna-Maria

---
Anna-Maria Behnsen (16):
      MAINTAINERS: Add missing file include/linux/delay.h
      timers: Move *sleep*() and timeout functions into a separate file
      timers: Update schedule_[hr]timeout*() related function descriptions
      timers: Rename usleep_idle_range() to usleep_range_idle()
      timers: Update function descriptions of sleep/delay related functions
      delay: Rework udelay and ndelay
      timers: Adjust flseep() to reflect reality
      mm/damon/core: Use generic upper bound recommondation for usleep_range()
      timers: Add a warning to usleep_range_state() for wrong order of arguments
      checkpatch: Remove links to outdated documentation
      regulator: core: Use fsleep() to get best sleep mechanism
      iopoll/regmap/phy/snd: Fix comment referencing outdated timer documentation
      powerpc/rtas: Use fsleep() to minimize additional sleep duration
      media: anysee: Fix and remove outdated comment
      timers/Documentation: Cleanup delay/sleep documentation
      checkpatch: Remove broken sleep/delay related checks

 Documentation/dev-tools/checkpatch.rst         |   6 -
 Documentation/timers/delay_sleep_functions.rst | 121 ++++++++
 Documentation/timers/index.rst                 |   2 +-
 Documentation/timers/timers-howto.rst          | 115 --------
 MAINTAINERS                                    |   2 +
 arch/powerpc/kernel/rtas.c                     |  21 +-
 drivers/media/usb/dvb-usb-v2/anysee.c          |  17 +-
 drivers/regulator/core.c                       |  47 +--
 include/asm-generic/delay.h                    |  96 +++++--
 include/linux/delay.h                          |  79 ++++--
 include/linux/iopoll.h                         |  52 ++--
 include/linux/phy.h                            |   9 +-
 include/linux/regmap.h                         |  38 +--
 kernel/time/Makefile                           |   2 +-
 kernel/time/hrtimer.c                          | 120 --------
 kernel/time/sleep_timeout.c                    | 377 +++++++++++++++++++++++++
 kernel/time/timer.c                            | 192 -------------
 mm/damon/core.c                                |   5 +-
 scripts/checkpatch.pl                          |  38 ---
 sound/soc/sof/ops.h                            |   8 +-
 20 files changed, 704 insertions(+), 643 deletions(-)

[PATCH v3 12/16] iopoll/regmap/phy/snd: Fix comment referencing outdated timer documentation

[Anna-Maria Behnsen]

Function descriptions in iopoll.h, regmap.h, phy.h and sound/soc/sof/ops.h
copied all the same outdated documentation about sleep/delay function
limitations. In those comments, the generic (and still outdated) timer
documentation file is referenced.

As proper function descriptions for used delay and sleep functions are in
place, simply update the descriptions to reference to them. While at it fix
missing colon after "Returns" in function description and move return value
description to the end of the function description.

Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: netdev@vger.kernel.org
Cc: linux-sound@vger.kernel.org
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch> # for phy.h
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
---
v2: Add cleanup of usage of 'Returns' in function description
---
 include/linux/iopoll.h | 52 +++++++++++++++++++++++++-------------------------
 include/linux/phy.h    |  9 +++++----
 include/linux/regmap.h | 38 ++++++++++++++++++------------------
 sound/soc/sof/ops.h    |  8 ++++----
 4 files changed, 54 insertions(+), 53 deletions(-)

diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h
index 19a7b00baff4..91324c331a4b 100644
--- a/include/linux/iopoll.h
+++ b/include/linux/iopoll.h
@@ -19,19 +19,19 @@
  * @op: accessor function (takes @args as its arguments)
  * @val: Variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  * @sleep_before_read: if it is true, sleep @sleep_us before read.
  * @args: arguments for @op poll
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
- * case, the last read value at @args is stored in @val. Must not
- * be called from atomic context if sleep_us or timeout_us are used.
- *
  * When available, you'll probably want to use one of the specialized
  * macros defined below rather than this macro directly.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
+ * case, the last read value at @args is stored in @val. Must not
+ * be called from atomic context if sleep_us or timeout_us are used.
  */
 #define read_poll_timeout(op, val, cond, sleep_us, timeout_us, \
 				sleep_before_read, args...) \
@@ -64,22 +64,22 @@
  * @op: accessor function (takes @args as its arguments)
  * @val: Variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @delay_us: Time to udelay between reads in us (0 tight-loops).  Should
- *            be less than ~10us since udelay is used (see
- *            Documentation/timers/timers-howto.rst).
+ * @delay_us: Time to udelay between reads in us (0 tight-loops). Please
+ *            read udelay() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  * @delay_before_read: if it is true, delay @delay_us before read.
  * @args: arguments for @op poll
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
- * case, the last read value at @args is stored in @val.
- *
  * This macro does not rely on timekeeping.  Hence it is safe to call even when
  * timekeeping is suspended, at the expense of an underestimation of wall clock
  * time, which is rather minimal with a non-zero delay_us.
  *
  * When available, you'll probably want to use one of the specialized
  * macros defined below rather than this macro directly.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
+ * case, the last read value at @args is stored in @val.
  */
 #define read_poll_timeout_atomic(op, val, cond, delay_us, timeout_us, \
 					delay_before_read, args...) \
@@ -119,17 +119,17 @@
  * @addr: Address to poll
  * @val: Variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
- * case, the last read value at @addr is stored in @val. Must not
- * be called from atomic context if sleep_us or timeout_us are used.
- *
  * When available, you'll probably want to use one of the specialized
  * macros defined below rather than this macro directly.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
+ * case, the last read value at @addr is stored in @val. Must not
+ * be called from atomic context if sleep_us or timeout_us are used.
  */
 #define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us)	\
 	read_poll_timeout(op, val, cond, sleep_us, timeout_us, false, addr)
@@ -140,16 +140,16 @@
  * @addr: Address to poll
  * @val: Variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @delay_us: Time to udelay between reads in us (0 tight-loops).  Should
- *            be less than ~10us since udelay is used (see
- *            Documentation/timers/timers-howto.rst).
+ * @delay_us: Time to udelay between reads in us (0 tight-loops). Please
+ *            read udelay() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
- * case, the last read value at @addr is stored in @val.
- *
  * When available, you'll probably want to use one of the specialized
  * macros defined below rather than this macro directly.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
+ * case, the last read value at @addr is stored in @val.
  */
 #define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \
 	read_poll_timeout_atomic(op, val, cond, delay_us, timeout_us, false, addr)
diff --git a/include/linux/phy.h b/include/linux/phy.h
index a98bc91a0cde..504766d4b2d5 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -1378,12 +1378,13 @@ int phy_read_mmd(struct phy_device *phydev, int devad, u32 regnum);
  * @regnum: The register on the MMD to read
  * @val: Variable to read the register into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  * @sleep_before_read: if it is true, sleep @sleep_us before read.
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
  * case, the last read value at @args is stored in @val. Must not
  * be called from atomic context if sleep_us or timeout_us are used.
  */
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index f9ccad32fc5c..75f162b60ba1 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -106,17 +106,17 @@ struct reg_sequence {
  * @addr: Address to poll
  * @val: Unsigned integer variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout or the regmap_read
+ * This is modelled after the readx_poll_timeout macros in linux/iopoll.h.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout or the regmap_read
  * error return value in case of a error read. In the two former cases,
  * the last read value at @addr is stored in @val. Must not be called
  * from atomic context if sleep_us or timeout_us are used.
- *
- * This is modelled after the readx_poll_timeout macros in linux/iopoll.h.
  */
 #define regmap_read_poll_timeout(map, addr, val, cond, sleep_us, timeout_us) \
 ({ \
@@ -133,20 +133,20 @@ struct reg_sequence {
  * @addr: Address to poll
  * @val: Unsigned integer variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @delay_us: Time to udelay between reads in us (0 tight-loops).
- *            Should be less than ~10us since udelay is used
- *            (see Documentation/timers/timers-howto.rst).
+ * @delay_us: Time to udelay between reads in us (0 tight-loops). Please
+ *            read udelay() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout or the regmap_read
- * error return value in case of a error read. In the two former cases,
- * the last read value at @addr is stored in @val.
- *
  * This is modelled after the readx_poll_timeout_atomic macros in linux/iopoll.h.
  *
  * Note: In general regmap cannot be used in atomic context. If you want to use
  * this macro then first setup your regmap for atomic use (flat or no cache
  * and MMIO regmap).
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout or the regmap_read
+ * error return value in case of a error read. In the two former cases,
+ * the last read value at @addr is stored in @val.
  */
 #define regmap_read_poll_timeout_atomic(map, addr, val, cond, delay_us, timeout_us) \
 ({ \
@@ -177,17 +177,17 @@ struct reg_sequence {
  * @field: Regmap field to read from
  * @val: Unsigned integer variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout or the regmap_field_read
+ * This is modelled after the readx_poll_timeout macros in linux/iopoll.h.
+ *
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout or the regmap_field_read
  * error return value in case of a error read. In the two former cases,
  * the last read value at @addr is stored in @val. Must not be called
  * from atomic context if sleep_us or timeout_us are used.
- *
- * This is modelled after the readx_poll_timeout macros in linux/iopoll.h.
  */
 #define regmap_field_read_poll_timeout(field, val, cond, sleep_us, timeout_us) \
 ({ \
diff --git a/sound/soc/sof/ops.h b/sound/soc/sof/ops.h
index 2584621c3b2d..d73644e85b6e 100644
--- a/sound/soc/sof/ops.h
+++ b/sound/soc/sof/ops.h
@@ -597,12 +597,12 @@ snd_sof_is_chain_dma_supported(struct snd_sof_dev *sdev, u32 dai_type)
  * @addr: Address to poll
  * @val: Variable to read the value into
  * @cond: Break condition (usually involving @val)
- * @sleep_us: Maximum time to sleep between reads in us (0
- *            tight-loops).  Should be less than ~20ms since usleep_range
- *            is used (see Documentation/timers/timers-howto.rst).
+ * @sleep_us: Maximum time to sleep between reads in us (0 tight-loops). Please
+ *            read usleep_range() function description for details and
+ *            limitations.
  * @timeout_us: Timeout in us, 0 means never timeout
  *
- * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
+ * Returns: 0 on success and -ETIMEDOUT upon a timeout. In either
  * case, the last read value at @addr is stored in @val. Must not
  * be called from atomic context if sleep_us or timeout_us are used.
  *

-- 
2.39.5

Re: (subset) [PATCH v3 00/16] timers: Cleanup delay/sleep related mess

[Mark Brown]

On Mon, 14 Oct 2024 10:22:17 +0200, Anna-Maria Behnsen wrote:
> a question about which sleeping function should be used in acpi_os_sleep()
> started a discussion and examination about the existing documentation and
> implementation of functions which insert a sleep/delay.
> 
> The result of the discussion was, that the documentation is outdated and
> the implemented fsleep() reflects the outdated documentation but doesn't
> help to reflect reality which in turns leads to the queue which covers the
> following things:
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git for-next

Thanks!

[11/16] regulator: core: Use fsleep() to get best sleep mechanism
        commit: f20669fbcf99d0e15e94fb50929bb1c41618e197

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

Re: (subset) [PATCH v3 00/16] timers: Cleanup delay/sleep related mess

[Anna-Maria Behnsen]

Hi Mark,

Mark Brown <broonie@kernel.org> writes:

> On Mon, 14 Oct 2024 10:22:17 +0200, Anna-Maria Behnsen wrote:
>> a question about which sleeping function should be used in acpi_os_sleep()
>> started a discussion and examination about the existing documentation and
>> implementation of functions which insert a sleep/delay.
>> 
>> The result of the discussion was, that the documentation is outdated and
>> the implemented fsleep() reflects the outdated documentation but doesn't
>> help to reflect reality which in turns leads to the queue which covers the
>> following things:
>> 
>> [...]
>
> Applied to
>
>    https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git for-next
>

Would it be ok for you, if the patch is routed through tip tree? kernel
test robot triggers a warning for htmldoc that there is a reference to
the no longer existing file 'timer-howto.rst':

  https://lore.kernel.org/r/202410161059.a0f6IBwj-lkp@intel.com

Thanks,

	Anna-Maria

Re: (subset) [PATCH v3 00/16] timers: Cleanup delay/sleep related mess

[Mark Brown]

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On Fri, Oct 18, 2024 at 10:06:33AM +0200, Anna-Maria Behnsen wrote:

> Would it be ok for you, if the patch is routed through tip tree? kernel
> test robot triggers a warning for htmldoc that there is a reference to
> the no longer existing file 'timer-howto.rst':

>   https://lore.kernel.org/r/202410161059.a0f6IBwj-lkp@intel.com

It should be fine, worst case we just get a duplicate patch which
doesn't super matter.

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Re: (subset) [PATCH v3 00/16] timers: Cleanup delay/sleep related mess

[Mark Brown]

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On Fri, Oct 18, 2024 at 10:06:33AM +0200, Anna-Maria Behnsen wrote:

> Would it be ok for you, if the patch is routed through tip tree? kernel
> test robot triggers a warning for htmldoc that there is a reference to
> the no longer existing file 'timer-howto.rst':

>   https://lore.kernel.org/r/202410161059.a0f6IBwj-lkp@intel.com

Oh, and for that:

Reviewed-by: Mark Brown <broonie@kernel.org>

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