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@xxxxxxxxxxxxx>
> Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> 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
