[PATCH 1/2] cpusets: restructure the function update_cpumask() and update_nodemask()

Miao Xie
2008-06-04T02:13:03Z

extract two functions from update_cpumask() and update_nodemask().They will be
used later for updating tasks' cpus_allowed and mems_allowed after CPU/NODE
offline/online.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Acked-by: Paul Jackson <pj@sgi.com>

---
kernel/cpuset.c | 183 +++++++++++++++++++++++++++++++++----------------------
1 files changed, 110 insertions(+), 73 deletions(-)

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 039baa4..aa955ee 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -766,6 +766,37 @@ static void cpuset_change_cpumask(struct task_struct *tsk,
}

/**
+ * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
+ * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
+ *
+ * Called with cgroup_mutex held
+ *
+ * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
+ * calling callback functions for each.
+ *
+ * Return 0 if successful, -errno if not.
+ */
+static int update_tasks_cpumask(struct cpuset *cs)
+{
+ struct cgroup_scanner scan;
+ struct ptr_heap heap;
+ int retval;
+
+ retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, &started_after);
+ if (retval)
+ return retval;
+
+ scan.cg = cs->css.cgroup;
+ scan.test_task = cpuset_test_cpumask;
+ scan.process_task = cpuset_change_cpumask;
+ scan.heap = &heap;
+ retval = cgroup_scan_tasks(&scan);
+
+ heap_free(&heap);
+ return retval;
+}
+
+/**
* update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
* @cs: the cpuset to consider
* @buf: buffer of cpu numbers written to this cpuset
@@ -773,8 +804,6 @@ static void cpuset_change_cpumask(struct task_struct *tsk,
static int update_cpumask(struct cpuset *cs, char *buf)
{
struct cpuset trialcs;
- struct cgroup_scanner scan;
- struct ptr_heap heap;
int retval;
int is_load_balanced;

@@ -809,10 +838,6 @@ static int update_cpumask(struct cpuset *cs, char *buf)
if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed))
return 0;

- retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, &started_after);
- if (retval)
- return retval;
-
is_load_balanced = is_sched_load_balance(&trialcs);

mutex_lock(&callback_mutex);
@@ -823,12 +848,9 @@ static int update_cpumask(struct cpuset *cs, char *buf)
* Scan tasks in the cpuset, and update the cpumasks of any
* that need an update.
*/
- scan.cg = cs->css.cgroup;
- scan.test_task = cpuset_test_cpumask;
- scan.process_task = cpuset_change_cpumask;
- scan.heap = &heap;
- cgroup_scan_tasks(&scan);
- heap_free(&heap);
+ retval = update_tasks_cpumask(cs);
+ if (retval < 0)
+ return retval;

if (is_load_balanced)
rebuild_sched_domains();
@@ -884,74 +906,25 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
mutex_unlock(&callback_mutex);
}

-/*
- * Handle user request to change the 'mems' memory placement
- * of a cpuset. Needs to validate the request, update the
- * cpusets mems_allowed and mems_generation, and for each
- * task in the cpuset, rebind any vma mempolicies and if
- * the cpuset is marked 'memory_migrate', migrate the tasks
- * pages to the new memory.
- *
- * Call with cgroup_mutex held. May take callback_mutex during call.
- * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
- * lock each such tasks mm->mmap_sem, scan its vma's and rebind
- * their mempolicies to the cpusets new mems_allowed.
- */
-
static void *cpuset_being_rebound;

-static int update_nodemask(struct cpuset *cs, char *buf)
+/**
+ * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
+ * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
+ * @oldmem: old mems_allowed of cpuset cs
+ *
+ * Called with cgroup_mutex held
+ * Return 0 if successful, -errno if not.
+ */
+static int update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem)
{
- struct cpuset trialcs;
- nodemask_t oldmem;
struct task_struct *p;
struct mm_struct **mmarray;
int i, n, ntasks;
int migrate;
int fudge;
- int retval;
struct cgroup_iter it;
-
- /*
- * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
- * it's read-only
- */
- if (cs == &top_cpuset)
- return -EACCES;
-
- trialcs = *cs;
-
- /*
- * An empty mems_allowed is ok iff there are no tasks in the cpuset.
- * Since nodelist_parse() fails on an empty mask, we special case
- * that parsing. The validate_change() call ensures that cpusets
- * with tasks have memory.
- */
- buf = strstrip(buf);
- if (!*buf) {
- nodes_clear(trialcs.mems_allowed);
- } else {
- retval = nodelist_parse(buf, trialcs.mems_allowed);
- if (retval < 0)
- goto done;
-
- if (!nodes_subset(trialcs.mems_allowed,
- node_states[N_HIGH_MEMORY]))
- return -EINVAL;
- }
- oldmem = cs->mems_allowed;
- if (nodes_equal(oldmem, trialcs.mems_allowed)) {
- retval = 0; /* Too easy - nothing to do */
- goto done;
- }
- retval = validate_change(cs, &trialcs);
- if (retval < 0)
- goto done;
-
- mutex_lock(&callback_mutex);
- cs->mems_allowed = trialcs.mems_allowed;
- cs->mems_generation = cpuset_mems_generation++;
- mutex_unlock(&callback_mutex);
+ int retval;

cpuset_being_rebound = cs; /* causes mpol_dup() rebind */

@@ -1018,7 +991,7 @@ static int update_nodemask(struct cpuset *cs, char *buf)

mpol_rebind_mm(mm, &cs->mems_allowed);
if (migrate)
- cpuset_migrate_mm(mm, &oldmem, &cs->mems_allowed);
+ cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
mmput(mm);
}

@@ -1030,6 +1003,71 @@ done:
return retval;
}

+/*
+ * Handle user request to change the 'mems' memory placement
+ * of a cpuset. Needs to validate the request, update the
+ * cpusets mems_allowed and mems_generation, and for each
+ * task in the cpuset, rebind any vma mempolicies and if
+ * the cpuset is marked 'memory_migrate', migrate the tasks
+ * pages to the new memory.
+ *
+ * Call with cgroup_mutex held. May take callback_mutex during call.
+ * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
+ * lock each such tasks mm->mmap_sem, scan its vma's and rebind
+ * their mempolicies to the cpusets new mems_allowed.
+ */
+static int update_nodemask(struct cpuset *cs, char *buf)
+{
+ struct cpuset trialcs;
+ nodemask_t oldmem;
+ int retval;
+
+ /*
+ * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
+ * it's read-only
+ */
+ if (cs == &top_cpuset)
+ return -EACCES;
+
+ trialcs = *cs;
+
+ /*
+ * An empty mems_allowed is ok iff there are no tasks in the cpuset.
+ * Since nodelist_parse() fails on an empty mask, we special case
+ * that parsing. The validate_change() call ensures that cpusets
+ * with tasks have memory.
+ */
+ buf = strstrip(buf);
+ if (!*buf) {
+ nodes_clear(trialcs.mems_allowed);
+ } else {
+ retval = nodelist_parse(buf, trialcs.mems_allowed);
+ if (retval < 0)
+ goto done;
+
+ if (!nodes_subset(trialcs.mems_allowed,
+ node_states[N_HIGH_MEMORY]))
+ return -EINVAL;
+ }
+ oldmem = cs->mems_allowed;
+ if (nodes_equal(oldmem, trialcs.mems_allowed)) {
+ retval = 0; /* Too easy - nothing to do */
+ goto done;
+ }
+ retval = validate_change(cs, &trialcs);
+ if (retval < 0)
+ goto done;
+
+ mutex_lock(&callback_mutex);
+ cs->mems_allowed = trialcs.mems_allowed;
+ cs->mems_generation = cpuset_mems_generation++;
+ mutex_unlock(&callback_mutex);
+
+ retval = update_tasks_nodemask(cs, &oldmem);
+done:
+ return retval;
+}
+
int current_cpuset_is_being_rebound(void)
{
return task_cs(current) == cpuset_being_rebound;
@@ -1942,7 +1980,6 @@ void __init cpuset_init_smp(void)
}

/**
-
* cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
* @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
* @pmask: pointer to cpumask_t variable to receive cpus_allowed set.
--
1.5.4.rc3