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authorLi Zefan <lizf@cn.fujitsu.com>2008-09-13 02:33:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-09-13 14:41:50 -0700
commit4e74339af6a59c061cf02f1ac497766bca1de19a (patch)
tree0903456d2aced7e2e9534b3b3d1c5f58e1056b53
parentdea420ce0e2973e8ef1fd11fde6804c8d03a82ad (diff)
cpuset: avoid changing cpuset's cpus when -errno returned
After the patch: commit 0b2f630a28d53b5a2082a5275bc3334b10373508 Author: Miao Xie <miaox@cn.fujitsu.com> Date: Fri Jul 25 01:47:21 2008 -0700 cpusets: restructure the function update_cpumask() and update_nodemask() It might happen that 'echo 0 > /cpuset/sub/cpus' returned failure but 'cpus' has been changed, because cpus was changed before calling heap_init() which may return -ENOMEM. This patch restores the orginal behavior. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Paul Menage <menage@google.com> Cc: Paul Jackson <pj@sgi.com> Cc: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/cpuset.c37
1 files changed, 15 insertions, 22 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index f227bc17269..827cd9adccb 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -843,37 +843,25 @@ 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
+ * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
*
* 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.
+ * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
+ * if @heap != NULL.
*/
-static int update_tasks_cpumask(struct cpuset *cs)
+static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
{
struct cgroup_scanner scan;
- struct ptr_heap heap;
- int retval;
-
- /*
- * cgroup_scan_tasks() will initialize heap->gt for us.
- * heap_init() is still needed here for we should not change
- * cs->cpus_allowed when heap_init() fails.
- */
- retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
- 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;
+ scan.heap = heap;
+ cgroup_scan_tasks(&scan);
}
/**
@@ -883,6 +871,7 @@ static int update_tasks_cpumask(struct cpuset *cs)
*/
static int update_cpumask(struct cpuset *cs, const char *buf)
{
+ struct ptr_heap heap;
struct cpuset trialcs;
int retval;
int is_load_balanced;
@@ -917,6 +906,10 @@ static int update_cpumask(struct cpuset *cs, const char *buf)
if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed))
return 0;
+ retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
+ if (retval)
+ return retval;
+
is_load_balanced = is_sched_load_balance(&trialcs);
mutex_lock(&callback_mutex);
@@ -927,9 +920,9 @@ static int update_cpumask(struct cpuset *cs, const char *buf)
* Scan tasks in the cpuset, and update the cpumasks of any
* that need an update.
*/
- retval = update_tasks_cpumask(cs);
- if (retval < 0)
- return retval;
+ update_tasks_cpumask(cs, &heap);
+
+ heap_free(&heap);
if (is_load_balanced)
async_rebuild_sched_domains();
@@ -1965,7 +1958,7 @@ static void scan_for_empty_cpusets(const struct cpuset *root)
nodes_empty(cp->mems_allowed))
remove_tasks_in_empty_cpuset(cp);
else {
- update_tasks_cpumask(cp);
+ update_tasks_cpumask(cp, NULL);
update_tasks_nodemask(cp, &oldmems);
}
}