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Subject[PATCH v14 03/12] cpuset: Simply allocation and freeing of cpumasks
Date
The previous commit introduces a new subparts_cpus mask into the cpuset
data structure and a new tmpmasks structure. Managing the allocation
and freeing of those cpumasks is becoming more complex.

So a number of helper functions are added to simplify and streamline
the management of those cpumasks. To make it simple, all the cpumasks
are now pre-cleared on allocation.

Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/cgroup/cpuset.c | 110 ++++++++++++++++++++++++++++-------------
1 file changed, 77 insertions(+), 33 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 29a2bdc671fd..2ac9437ce8f1 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -455,6 +455,65 @@ static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
is_mem_exclusive(p) <= is_mem_exclusive(q);
}

+/**
+ * alloc_cpumasks - allocate three cpumasks for cpuset
+ * @cs: the cpuset that have cpumasks to be allocated.
+ * @tmp: the tmpmasks structure pointer
+ * Return: 0 if successful, -ENOMEM otherwise.
+ *
+ * Only one of the two input arguments should be non-NULL.
+ */
+static inline int alloc_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
+{
+ cpumask_var_t *pmask1, *pmask2, *pmask3;
+
+ if (cs) {
+ pmask1 = &cs->cpus_allowed;
+ pmask2 = &cs->effective_cpus;
+ pmask3 = &cs->subparts_cpus;
+ } else {
+ pmask1 = &tmp->new_cpus;
+ pmask2 = &tmp->addmask;
+ pmask3 = &tmp->delmask;
+ }
+
+ if (!zalloc_cpumask_var(pmask1, GFP_KERNEL))
+ return -ENOMEM;
+
+ if (!zalloc_cpumask_var(pmask2, GFP_KERNEL))
+ goto free_one;
+
+ if (!zalloc_cpumask_var(pmask3, GFP_KERNEL))
+ goto free_two;
+
+ return 0;
+
+free_two:
+ free_cpumask_var(*pmask2);
+free_one:
+ free_cpumask_var(*pmask1);
+ return -ENOMEM;
+}
+
+/**
+ * free_cpumasks - free cpumasks in a tmpmasks structure
+ * @cs: the cpuset that have cpumasks to be free.
+ * @tmp: the tmpmasks structure pointer
+ */
+static inline void free_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
+{
+ if (cs) {
+ free_cpumask_var(cs->cpus_allowed);
+ free_cpumask_var(cs->effective_cpus);
+ free_cpumask_var(cs->subparts_cpus);
+ }
+ if (tmp) {
+ free_cpumask_var(tmp->new_cpus);
+ free_cpumask_var(tmp->addmask);
+ free_cpumask_var(tmp->delmask);
+ }
+}
+
/**
* alloc_trial_cpuset - allocate a trial cpuset
* @cs: the cpuset that the trial cpuset duplicates
@@ -467,31 +526,24 @@ static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
if (!trial)
return NULL;

- if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL))
- goto free_cs;
- if (!alloc_cpumask_var(&trial->effective_cpus, GFP_KERNEL))
- goto free_cpus;
+ if (alloc_cpumasks(trial, NULL)) {
+ kfree(trial);
+ return NULL;
+ }

cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
cpumask_copy(trial->effective_cpus, cs->effective_cpus);
return trial;
-
-free_cpus:
- free_cpumask_var(trial->cpus_allowed);
-free_cs:
- kfree(trial);
- return NULL;
}

/**
- * free_trial_cpuset - free the trial cpuset
- * @trial: the trial cpuset to be freed
+ * free_cpuset - free the cpuset
+ * @cs: the cpuset to be freed
*/
-static void free_trial_cpuset(struct cpuset *trial)
+static inline void free_cpuset(struct cpuset *cs)
{
- free_cpumask_var(trial->effective_cpus);
- free_cpumask_var(trial->cpus_allowed);
- kfree(trial);
+ free_cpumasks(cs, NULL);
+ kfree(cs);
}

/*
@@ -1385,7 +1437,7 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
if (spread_flag_changed)
update_tasks_flags(cs);
out:
- free_trial_cpuset(trialcs);
+ free_cpuset(trialcs);
return err;
}

@@ -1769,7 +1821,7 @@ static ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
break;
}

- free_trial_cpuset(trialcs);
+ free_cpuset(trialcs);
out_unlock:
mutex_unlock(&cpuset_mutex);
kernfs_unbreak_active_protection(of->kn);
@@ -2024,26 +2076,19 @@ cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
cs = kzalloc(sizeof(*cs), GFP_KERNEL);
if (!cs)
return ERR_PTR(-ENOMEM);
- if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL))
- goto free_cs;
- if (!alloc_cpumask_var(&cs->effective_cpus, GFP_KERNEL))
- goto free_cpus;
+
+ if (alloc_cpumasks(cs, NULL)) {
+ kfree(cs);
+ return ERR_PTR(-ENOMEM);
+ }

set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
- cpumask_clear(cs->cpus_allowed);
nodes_clear(cs->mems_allowed);
- cpumask_clear(cs->effective_cpus);
nodes_clear(cs->effective_mems);
fmeter_init(&cs->fmeter);
cs->relax_domain_level = -1;

return &cs->css;
-
-free_cpus:
- free_cpumask_var(cs->cpus_allowed);
-free_cs:
- kfree(cs);
- return ERR_PTR(-ENOMEM);
}

static int cpuset_css_online(struct cgroup_subsys_state *css)
@@ -2134,9 +2179,7 @@ static void cpuset_css_free(struct cgroup_subsys_state *css)
{
struct cpuset *cs = css_cs(css);

- free_cpumask_var(cs->effective_cpus);
- free_cpumask_var(cs->cpus_allowed);
- kfree(cs);
+ free_cpuset(cs);
}

static void cpuset_bind(struct cgroup_subsys_state *root_css)
@@ -2200,6 +2243,7 @@ int __init cpuset_init(void)

BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL));
BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL));
+ BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL));

cpumask_setall(top_cpuset.cpus_allowed);
nodes_setall(top_cpuset.mems_allowed);
--
2.18.0
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