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SubjectRe: [PATCH 11/14] irq: add support for allocating (and affinitizing) sets of IRQs
On Mon, Oct 29, 2018 at 10:37:35AM -0600, Jens Axboe wrote:
> diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
> index f4f29b9d90ee..2046a0f0f0f1 100644
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -180,6 +180,7 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
> int curvec, usedvecs;
> cpumask_var_t nmsk, npresmsk, *node_to_cpumask;
> struct cpumask *masks = NULL;
> + int i, nr_sets;
>
> /*
> * If there aren't any vectors left after applying the pre/post
> @@ -210,10 +211,23 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
> get_online_cpus();
> build_node_to_cpumask(node_to_cpumask);
>
> - /* Spread on present CPUs starting from affd->pre_vectors */
> - usedvecs = irq_build_affinity_masks(affd, curvec, affvecs,
> - node_to_cpumask, cpu_present_mask,
> - nmsk, masks);
> + /*
> + * Spread on present CPUs starting from affd->pre_vectors. If we
> + * have multiple sets, build each sets affinity mask separately.
> + */
> + nr_sets = affd->nr_sets;
> + if (!nr_sets)
> + nr_sets = 1;
> +
> + for (i = 0, usedvecs = 0; i < nr_sets; i++) {
> + int this_vecs = affd->sets ? affd->sets[i] : affvecs;
> + int nr;
> +
> + nr = irq_build_affinity_masks(affd, curvec, this_vecs,
> + node_to_cpumask, cpu_present_mask,
> + nmsk, masks + usedvecs);
> + usedvecs += nr;
> + }


While the code below returns the appropriate number of possible vectors
when a set requested too many, the above code is still using the value
from the set, which may exceed 'nvecs' used to kcalloc 'masks', so
'masks + usedvecs' may go out of bounds.


> /*
> * Spread on non present CPUs starting from the next vector to be
> @@ -258,13 +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 ret;
> + int set_vecs;
>
> if (resv > minvec)
> return 0;
>
> - get_online_cpus();
> - ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs) + resv;
> - put_online_cpus();
> - return ret;
> + if (affd->nr_sets) {
> + int 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 + min(set_vecs, vecs);
> }


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