Shall we call this Dynamic tasklets ?

There is a typical problem to be solved as mentioned in the below small note:-

 To solve this problem, a solution is provided using dynamically allocated tasklet as below and explanation is provided as necessary with the code.

>
> -------------------------------------------------------------------------
> static void t_fun(unsigned long t_arg)
> {
>         struct my_dat *data = (struct my_dat *)t_arg;
>         atomic_inc(&counter_bh);
>         pr_info("In BH: counter_th = %d, counter_bh = %d, jiffies=%ld, %ld\n",
>                 atomic_read(&counter_th), atomic_read(&counter_bh),
>                 data->jiffies, jiffies);
>         kfree(data);
> }
>
> static irqreturn_t my_interrupt(int irq, void *dev_id)
> {
>         struct tasklet_struct *t;
>         struct my_dat *data;
>
>         data = (struct my_dat *)kmalloc(sizeof(struct my_dat), GFP_ATOMIC);
>         t = &data->tsk;
>         data->jiffies = jiffies;
>
>         tasklet_init(t, t_fun, (unsigned long)data);
>
>         atomic_inc(&counter_th);
>         tasklet_schedule(t);
>         mdelay(delay);          /* hoke up a delay to try to cause pileup */
>         return IRQ_NONE;        /* we return IRQ_NONE because we are just observing */
> }
>

This part of code initializes a new tasklet everytime on the IRQ. Hence each time the processor services the IRQ there is a new  tasklet is getting created however the function remains the same. Note:- In traditional drivers usually a single tasklet is used and scheduled multiple times using the IRQ

> module_init(my_generic_init);
> module_exit(my_generic_exit);
>
> -------------------------------------------------------------------------
>
> Above solution will not miss any bottom halves.
> Can somebody explains me why above solution is working ?
> What is so special about dynamic tasklets ?

The  solution works because the new tasklet is created everytime with the same callback function. Note that the function should be fully re-entrant for such use-cases which is done using the local variable - arg/data in this case.

Reference :- http://lists.kernelnewbies.org/pipermail/kernelnewbies/2018-June/019197.html