Commit b783a626 authored by Chen Ridong's avatar Chen Ridong Committed by Tejun Heo
Browse files

cpuset: move the root cpuset write check earlier 



The 'cpus' or 'mems' lists of the top_cpuset cannot be modified.
This check can be moved before acquiring any locks as a common code
block to improve efficiency and maintainability.

Signed-off-by: default avatarChen Ridong <chenridong@huawei.com>
Reviewed-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 58ab6d25

kernel/cgroup/cpuset.c

+4 −13
Original line number Diff line number Diff line
@@ -2338,10 +2338,6 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, 
	bool force = false;

	int old_prs = cs->partition_root_state;



	/* top_cpuset.cpus_allowed tracks cpu_active_mask; it's read-only */

	if (cs == &top_cpuset)

		return -EACCES;



	/*

	 * An empty cpus_allowed is ok only if the cpuset has no tasks.

	 * Since cpulist_parse() fails on an empty mask, we special case
@@ -2802,15 +2798,6 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, 
{

	int retval;



	/*

	 * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];

	 * it's read-only

	 */

	if (cs == &top_cpuset) {

		retval = -EACCES;

		goto done;

	}



	/*

	 * 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
@@ -3280,6 +3267,10 @@ ssize_t cpuset_write_resmask(struct kernfs_open_file *of, 
	struct cpuset *trialcs;

	int retval = -ENODEV;



	/* root is read-only */

	if (cs == &top_cpuset)

		return -EACCES;



	buf = strstrip(buf);

	cpuset_full_lock();

	if (!is_cpuset_online(cs))