linux/kernel/irq/affinity.c
Ming Lei 491beed3b1 genirq/affinity: Create affinity mask for single vector
Since commit c66d4bd110 ("genirq/affinity: Add new callback for
(re)calculating interrupt sets"), irq_create_affinity_masks() returns
NULL in case of single vector. This change has caused regression on some
drivers, such as lpfc.

The problem is that single vector requests can happen in some generic cases:

  1) kdump kernel

  2) irq vectors resource is close to exhaustion.

If in that situation the affinity mask for a single vector is not created,
every caller has to handle the special case.

There is no reason why the mask cannot be created, so remove the check for
a single vector and create the mask.

Fixes: c66d4bd110 ("genirq/affinity: Add new callback for (re)calculating interrupt sets")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190805011906.5020-1-ming.lei@redhat.com
2019-08-08 08:47:55 +02:00

344 lines
8.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2016 Thomas Gleixner.
* Copyright (C) 2016-2017 Christoph Hellwig.
*/
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/cpu.h>
static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
unsigned int cpus_per_vec)
{
const struct cpumask *siblmsk;
int cpu, sibl;
for ( ; cpus_per_vec > 0; ) {
cpu = cpumask_first(nmsk);
/* Should not happen, but I'm too lazy to think about it */
if (cpu >= nr_cpu_ids)
return;
cpumask_clear_cpu(cpu, nmsk);
cpumask_set_cpu(cpu, irqmsk);
cpus_per_vec--;
/* If the cpu has siblings, use them first */
siblmsk = topology_sibling_cpumask(cpu);
for (sibl = -1; cpus_per_vec > 0; ) {
sibl = cpumask_next(sibl, siblmsk);
if (sibl >= nr_cpu_ids)
break;
if (!cpumask_test_and_clear_cpu(sibl, nmsk))
continue;
cpumask_set_cpu(sibl, irqmsk);
cpus_per_vec--;
}
}
}
static cpumask_var_t *alloc_node_to_cpumask(void)
{
cpumask_var_t *masks;
int node;
masks = kcalloc(nr_node_ids, sizeof(cpumask_var_t), GFP_KERNEL);
if (!masks)
return NULL;
for (node = 0; node < nr_node_ids; node++) {
if (!zalloc_cpumask_var(&masks[node], GFP_KERNEL))
goto out_unwind;
}
return masks;
out_unwind:
while (--node >= 0)
free_cpumask_var(masks[node]);
kfree(masks);
return NULL;
}
static void free_node_to_cpumask(cpumask_var_t *masks)
{
int node;
for (node = 0; node < nr_node_ids; node++)
free_cpumask_var(masks[node]);
kfree(masks);
}
static void build_node_to_cpumask(cpumask_var_t *masks)
{
int cpu;
for_each_possible_cpu(cpu)
cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]);
}
static int get_nodes_in_cpumask(cpumask_var_t *node_to_cpumask,
const struct cpumask *mask, nodemask_t *nodemsk)
{
int n, nodes = 0;
/* Calculate the number of nodes in the supplied affinity mask */
for_each_node(n) {
if (cpumask_intersects(mask, node_to_cpumask[n])) {
node_set(n, *nodemsk);
nodes++;
}
}
return nodes;
}
static int __irq_build_affinity_masks(unsigned int startvec,
unsigned int numvecs,
unsigned int firstvec,
cpumask_var_t *node_to_cpumask,
const struct cpumask *cpu_mask,
struct cpumask *nmsk,
struct irq_affinity_desc *masks)
{
unsigned int n, nodes, cpus_per_vec, extra_vecs, done = 0;
unsigned int last_affv = firstvec + numvecs;
unsigned int curvec = startvec;
nodemask_t nodemsk = NODE_MASK_NONE;
if (!cpumask_weight(cpu_mask))
return 0;
nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);
/*
* If the number of nodes in the mask is greater than or equal the
* number of vectors we just spread the vectors across the nodes.
*/
if (numvecs <= nodes) {
for_each_node_mask(n, nodemsk) {
cpumask_or(&masks[curvec].mask, &masks[curvec].mask,
node_to_cpumask[n]);
if (++curvec == last_affv)
curvec = firstvec;
}
return numvecs;
}
for_each_node_mask(n, nodemsk) {
unsigned int ncpus, v, vecs_to_assign, vecs_per_node;
/* Spread the vectors per node */
vecs_per_node = (numvecs - (curvec - firstvec)) / nodes;
/* Get the cpus on this node which are in the mask */
cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
/* Calculate the number of cpus per vector */
ncpus = cpumask_weight(nmsk);
vecs_to_assign = min(vecs_per_node, ncpus);
/* Account for rounding errors */
extra_vecs = ncpus - vecs_to_assign * (ncpus / vecs_to_assign);
for (v = 0; curvec < last_affv && v < vecs_to_assign;
curvec++, v++) {
cpus_per_vec = ncpus / vecs_to_assign;
/* Account for extra vectors to compensate rounding errors */
if (extra_vecs) {
cpus_per_vec++;
--extra_vecs;
}
irq_spread_init_one(&masks[curvec].mask, nmsk,
cpus_per_vec);
}
done += v;
if (done >= numvecs)
break;
if (curvec >= last_affv)
curvec = firstvec;
--nodes;
}
return done;
}
/*
* build affinity in two stages:
* 1) spread present CPU on these vectors
* 2) spread other possible CPUs on these vectors
*/
static int irq_build_affinity_masks(unsigned int startvec, unsigned int numvecs,
unsigned int firstvec,
struct irq_affinity_desc *masks)
{
unsigned int curvec = startvec, nr_present, nr_others;
cpumask_var_t *node_to_cpumask;
cpumask_var_t nmsk, npresmsk;
int ret = -ENOMEM;
if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
return ret;
if (!zalloc_cpumask_var(&npresmsk, GFP_KERNEL))
goto fail_nmsk;
node_to_cpumask = alloc_node_to_cpumask();
if (!node_to_cpumask)
goto fail_npresmsk;
ret = 0;
/* Stabilize the cpumasks */
get_online_cpus();
build_node_to_cpumask(node_to_cpumask);
/* Spread on present CPUs starting from affd->pre_vectors */
nr_present = __irq_build_affinity_masks(curvec, numvecs,
firstvec, node_to_cpumask,
cpu_present_mask, nmsk, masks);
/*
* Spread on non present CPUs starting from the next vector to be
* handled. If the spreading of present CPUs already exhausted the
* vector space, assign the non present CPUs to the already spread
* out vectors.
*/
if (nr_present >= numvecs)
curvec = firstvec;
else
curvec = firstvec + nr_present;
cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask);
nr_others = __irq_build_affinity_masks(curvec, numvecs,
firstvec, node_to_cpumask,
npresmsk, nmsk, masks);
put_online_cpus();
if (nr_present < numvecs)
WARN_ON(nr_present + nr_others < numvecs);
free_node_to_cpumask(node_to_cpumask);
fail_npresmsk:
free_cpumask_var(npresmsk);
fail_nmsk:
free_cpumask_var(nmsk);
return ret;
}
static void default_calc_sets(struct irq_affinity *affd, unsigned int affvecs)
{
affd->nr_sets = 1;
affd->set_size[0] = affvecs;
}
/**
* irq_create_affinity_masks - Create affinity masks for multiqueue spreading
* @nvecs: The total number of vectors
* @affd: Description of the affinity requirements
*
* Returns the irq_affinity_desc pointer or NULL if allocation failed.
*/
struct irq_affinity_desc *
irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
{
unsigned int affvecs, curvec, usedvecs, i;
struct irq_affinity_desc *masks = NULL;
/*
* Determine the number of vectors which need interrupt affinities
* assigned. If the pre/post request exhausts the available vectors
* then nothing to do here except for invoking the calc_sets()
* callback so the device driver can adjust to the situation.
*/
if (nvecs > affd->pre_vectors + affd->post_vectors)
affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
else
affvecs = 0;
/*
* Simple invocations do not provide a calc_sets() callback. Install
* the generic one.
*/
if (!affd->calc_sets)
affd->calc_sets = default_calc_sets;
/* Recalculate the sets */
affd->calc_sets(affd, affvecs);
if (WARN_ON_ONCE(affd->nr_sets > IRQ_AFFINITY_MAX_SETS))
return NULL;
/* Nothing to assign? */
if (!affvecs)
return NULL;
masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
if (!masks)
return NULL;
/* Fill out vectors at the beginning that don't need affinity */
for (curvec = 0; curvec < affd->pre_vectors; curvec++)
cpumask_copy(&masks[curvec].mask, irq_default_affinity);
/*
* Spread on present CPUs starting from affd->pre_vectors. If we
* have multiple sets, build each sets affinity mask separately.
*/
for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) {
unsigned int this_vecs = affd->set_size[i];
int ret;
ret = irq_build_affinity_masks(curvec, this_vecs,
curvec, masks);
if (ret) {
kfree(masks);
return NULL;
}
curvec += this_vecs;
usedvecs += this_vecs;
}
/* Fill out vectors at the end that don't need affinity */
if (usedvecs >= affvecs)
curvec = affd->pre_vectors + affvecs;
else
curvec = affd->pre_vectors + usedvecs;
for (; curvec < nvecs; curvec++)
cpumask_copy(&masks[curvec].mask, irq_default_affinity);
/* Mark the managed interrupts */
for (i = affd->pre_vectors; i < nvecs - affd->post_vectors; i++)
masks[i].is_managed = 1;
return masks;
}
/**
* irq_calc_affinity_vectors - Calculate the optimal number of vectors
* @minvec: The minimum number of vectors available
* @maxvec: The maximum number of vectors available
* @affd: Description of the affinity requirements
*/
unsigned int irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
const struct irq_affinity *affd)
{
unsigned int resv = affd->pre_vectors + affd->post_vectors;
unsigned int set_vecs;
if (resv > minvec)
return 0;
if (affd->calc_sets) {
set_vecs = maxvec - resv;
} else {
get_online_cpus();
set_vecs = cpumask_weight(cpu_possible_mask);
put_online_cpus();
}
return resv + min(set_vecs, maxvec - resv);
}