cpuset: Simply allocation and freeing of cpumasks

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>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 29a2bdc671fd849833296270b4ce2a54b59f2fd2..2ac9437ce8f1825b4ca4c75becf580dd97373f19 100644 (file)
--- 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);