On 10/25/18 3:52 PM, Keith Busch wrote:
> On Thu, Oct 25, 2018 at 03:16:23PM -0600, Jens Axboe wrote:
>> A driver may have a need to allocate multiple sets of MSI/MSI-X
>> interrupts, and have them appropriately affinitized. Add support for
>> defining a number of sets in the irq_affinity structure, of varying
>> sizes, and get each set affinitized correctly across the machine.
>
> <>
>
>> @@ -258,13 +272,18 @@ int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity
>> {
>> int resv = affd->pre_vectors + affd->post_vectors;
>> int vecs = maxvec - resv;
>> + int i, set_vecs;
>> int ret;
>>
>> if (resv > minvec)
>> return 0;
>>
>> get_online_cpus();
>> - ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs) + resv;
>> + ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs);
>> put_online_cpus();
>> - return ret;
>> +
>> + for (i = 0, set_vecs = 0; i < affd->nr_sets; i++)
>> + set_vecs += affd->sets[i];
>> +
>> + return resv + max(ret, set_vecs);
>> }
>
> This is looking pretty good, but we may risk getting into an infinite
> loop in __pci_enable_msix_range() if we're requesting too many vectors
> in a set: the above code may continue returning set_vecs, overriding
> the reduced nvec that pci requested, and pci msix initialization will
> continue to fail because it is repeatedly requesting to activate the
> same vector count that failed before.
Good catch, we always want to be using min() with the passed in maxvec
in there. How about this incremental?
diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index 0055e252e438..2046a0f0f0f1 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -272,18 +272,21 @@ int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity
{
int resv = affd->pre_vectors + affd->post_vectors;
int vecs = maxvec - resv;
- int i, set_vecs;
- int ret;
+ int set_vecs;
if (resv > minvec)
return 0;
- get_online_cpus();
- ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs);
- put_online_cpus();
+ if (affd->nr_sets) {
+ int i;
- for (i = 0, set_vecs = 0; i < affd->nr_sets; i++)
- set_vecs += affd->sets[i];
+ for (i = 0, set_vecs = 0; i < affd->nr_sets; i++)
+ set_vecs += affd->sets[i];
+ } else {
+ get_online_cpus();
+ set_vecs = cpumask_weight(cpu_possible_mask);
+ put_online_cpus();
+ }
- return resv + max(ret, set_vecs);
+ return resv + min(set_vecs, vecs);
}
--
Jens Axboe
