> On 29 Oct 2017, at 18:36, Philippe Gerum <r...@xenomai.org> wrote:
>
> On 10/23/2017 04:59 PM, Christoph Muellner wrote:
>> To set a GPIO interrupt's CPU affinity, we simply call
>> rtdm_irq_affinity() with a proper bitmask.
>>
>> Signed-off-by: Christoph Muellner <christoph.muell...@theobroma-systems.com>
>> ---
>> kernel/drivers/gpio/gpio-core.c | 25 +++++++++++++++++++++++++
>> 1 file changed, 25 insertions(+)
>>
>> diff --git a/kernel/drivers/gpio/gpio-core.c
>> b/kernel/drivers/gpio/gpio-core.c
>> index 55594f6ae..84153a937 100644
>> --- a/kernel/drivers/gpio/gpio-core.c
>> +++ b/kernel/drivers/gpio/gpio-core.c
>> @@ -118,6 +118,23 @@ static void release_gpio_irq(unsigned int gpio, struct
>> rtdm_gpio_pin *pin,
>> chan->requested = false;
>> }
>>
>> +static int set_gpio_irq_affinity(struct rtdm_gpio_pin *pin, int val)
>> +{
>> + cpumask_t tgt;
>> + unsigned int i = 0;
>> +
>> + cpumask_clear(&tgt);
>> +
>> + while (val) {
>> + if (val & (1 << i))
>> + cpumask_set_cpu(i, &tgt);
>> + val &= ~(1 << i);
>> + i++;
>> + }
>> +
>> + return rtdm_irq_affinity(&pin->irqh, tgt);
>> +}
>> +
>
> Reflecting the change from int -> cpu_set_t in the ABI, we could have
> something along these lines instead:
>
> static int set_gpio_irq_affinity(struct rtdm_gpio_pin *pin, unsigned
> long __user *u_set, size_t setsize)
> {
> cpumask_var_t mask;
> int ret;
>
> if (!alloc_cpumask_var(&mask, GFP_KERNEL))
> return -ENOMEM;
>
> ret = get_user_cpu_mask(u_set, setsize, mask);
> if (ret == 0)
> ret = do_set_gpio_affinity(pin, mask);
>
> free_cpumask_var(mask);
>
> ...
Thanks for your review!
I guess this is inspired from kernel/sched/core.c's sched_setaffinity() syscall
handler.
However, I prefer not to use the use the alloc_cpumask_var() function.
The reason is, that "alloc_cpumask_var allocates only nr_cpumask_bits bits",
while
a "real cpumask_t always has NR_CPUS bits" (quoting from the warning in
linux/cpumask.h).
As rtdm_irq_affinity() expects a cpumask_t as second argument, we would copy
a too small mask. Instead I'm going to use a (stack allocated) cpumask_t.
The reason, why this is not a problem in case of sched_affinity, is that there
the
mask is passed as a pointer (struct cpumask* aka. cpumask_t*).
I'll post an updated patch series (including the requested documentation) today
or tomorrow.
Thanks,
Christoph
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 874 bytes
Desc: Message signed with OpenPGP
URL:
<http://xenomai.org/pipermail/xenomai/attachments/20171103/c3606279/attachment.sig>
_______________________________________________
Xenomai mailing list
Xenomai@xenomai.org
https://xenomai.org/mailman/listinfo/xenomai
