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Commit 4e74339a authored by Li Zefan's avatar Li Zefan Committed by Linus Torvalds
Browse files

cpuset: avoid changing cpuset's cpus when -errno returned 



After the patch:

commit 0b2f630a
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: default avatarLi Zefan <lizf@cn.fujitsu.com>
Acked-by: default avatarPaul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dea420ce

kernel/cpuset.c

+15 −22
Original line number Diff line number Diff line
@@ -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);

		}

	}