netdev - Re: [patch V2 07/17] timers: Update kernel-doc for various functions

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Date:   Wed, 23 Nov 2022 11:23:18 +0100 (CET)
From:   Anna-Maria Behnsen <anna-maria@...utronix.de>
To:     Thomas Gleixner <tglx@...utronix.de>
cc:     LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...uxfoundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Julia Lawall <Julia.Lawall@...ia.fr>,
        Arnd Bergmann <arnd@...db.de>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Marc Zyngier <maz@...nel.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        linux-bluetooth@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Subject: Re: [patch V2 07/17] timers: Update kernel-doc for various
 functions

On Tue, 22 Nov 2022, Thomas Gleixner wrote:

> The kernel-doc of timer related functions is partially uncomprehensible
> word salad. Rewrite it to make it useful.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Tested-by: Guenter Roeck <linux@...ck-us.net>
> ---
> V2: Refined comments (Steven)
> ---
>  kernel/time/timer.c |  148 ++++++++++++++++++++++++++++++----------------------
>  1 file changed, 88 insertions(+), 60 deletions(-)
> 
> --- a/kernel/time/timer.c
> +++ b/kernel/time/timer.c
> @@ -1200,11 +1212,12 @@ void add_timer(struct timer_list *timer)
>  EXPORT_SYMBOL(add_timer);
>  
>  /**
> - * add_timer_on - start a timer on a particular CPU
> - * @timer: the timer to be added
> - * @cpu: the CPU to start it on
> + * add_timer_on - Start a timer on a particular CPU
> + * @timer:	The timer to be started
> + * @cpu:	The CPU to start it on
>   *
> - * This is not very scalable on SMP. Double adds are not possible.
> + * This can only operate on an inactive timer. Attempts to invoke this on
> + * an active timer are rejected with a warning.

This is also true for add_timer(). Is it possible to add this to
add_timer() function description and just referencing to add_timer()
function description in add_timer_on()? They behave the same, only
difference is the CPU where the timer is enqueued.

>   */
>  void add_timer_on(struct timer_list *timer, int cpu)
>  {
> @@ -1240,15 +1253,18 @@ void add_timer_on(struct timer_list *tim
>  EXPORT_SYMBOL_GPL(add_timer_on);
>  
>  /**
> - * del_timer - deactivate a timer.
> - * @timer: the timer to be deactivated
> - *
> - * del_timer() deactivates a timer - this works on both active and inactive
> - * timers.
> + * del_timer - Deactivate a timer.
> + * @timer:	The timer to be deactivated
>   *
> - * The function returns whether it has deactivated a pending timer or not.
> - * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
> - * active timer returns 1.)
> + * The function only deactivates a pending timer, but contrary to
> + * del_timer_sync() it does not take into account whether the timers

timer's callback function or timer callback function (if the latter one is
used, please replace it in description for del_timer_sync() as well).

> + * callback function is concurrently executed on a different CPU or not.
> + * It neither prevents rearming of the timer.  If @timer can be rearmed

NIT                                             ^ two whitespaces

> + * concurrently then the return value of this function is meaningless.
> + *
> + * Return:
> + * * %0 - The timer was not pending
> + * * %1 - The timer was pending and deactivated
>   */
>  int del_timer(struct timer_list *timer)
>  {

Thanks,

	Anna-Maria