cgroup/cpuset: Move housekeeping_update()/rebuild_sched_domains() together

With the latest changes in sched/isolation.c, rebuild_sched_domains*()
requires the HK_TYPE_DOMAIN housekeeping cpumask to be properly
updated first, if needed, before the sched domains can be
rebuilt. So the two naturally fit together. Do that by creating a new
update_hk_sched_domains() helper to house both actions.

The name of the isolated_cpus_updating flag to control the
call to housekeeping_update() is now outdated. So change it to
update_housekeeping to better reflect its purpose. Also move the call
to update_hk_sched_domains() to the end of cpuset and hotplug operations
before releasing the cpuset_mutex.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index edc67c6aa55363caaa2d67a39310ee752fed196d..14b07a283a2c23c85654aff41c95306548589c7c 100644 (file)
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -130,10 +130,9 @@ static cpumask_var_t       subpartitions_cpus;     /* RWCS */
 static cpumask_var_t   isolated_cpus;          /* CSCB */
 
 /*
- * Set if isolated_cpus is being updated in the current cpuset_mutex
- * critical section.
+ * Set if housekeeping cpumasks are to be updated.
  */
-static bool            isolated_cpus_updating; /* RWCS */
+static bool            update_housekeeping;    /* RWCS */
 
 /*
  * A flag to force sched domain rebuild at the end of an operation.
@@ -1189,7 +1188,7 @@ static void isolated_cpus_update(int old_prs, int new_prs, struct cpumask *xcpus
                        return;
                cpumask_andnot(isolated_cpus, isolated_cpus, xcpus);
        }
-       isolated_cpus_updating = true;
+       update_housekeeping = true;
 }
 
 /*
@@ -1307,22 +1306,22 @@ static bool prstate_housekeeping_conflict(int prstate, struct cpumask *new_cpus)
 }
 
 /*
- * update_isolation_cpumasks - Update external isolation related CPU masks
+ * update_hk_sched_domains - Update HK cpumasks & rebuild sched domains
  *
- * The following external CPU masks will be updated if necessary:
- * - workqueue unbound cpumask
+ * Update housekeeping cpumasks and rebuild sched domains if necessary.
+ * This should be called at the end of cpuset or hotplug actions.
  */
-static void update_isolation_cpumasks(void)
+static void update_hk_sched_domains(void)
 {
-       int ret;
-
-       if (!isolated_cpus_updating)
-               return;
-
-       ret = housekeeping_update(isolated_cpus);
-       WARN_ON_ONCE(ret < 0);
-
-       isolated_cpus_updating = false;
+       if (update_housekeeping) {
+               /* Updating HK cpumasks implies rebuild sched domains */
+               WARN_ON_ONCE(housekeeping_update(isolated_cpus));
+               update_housekeeping = false;
+               force_sd_rebuild = true;
+       }
+       /* force_sd_rebuild will be cleared in rebuild_sched_domains_locked() */
+       if (force_sd_rebuild)
+               rebuild_sched_domains_locked();
 }
 
 /**
@@ -1473,7 +1472,6 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs,
        cs->remote_partition = true;
        cpumask_copy(cs->effective_xcpus, tmp->new_cpus);
        spin_unlock_irq(&callback_lock);
-       update_isolation_cpumasks();
        cpuset_force_rebuild();
        cs->prs_err = 0;
 
@@ -1518,7 +1516,6 @@ static void remote_partition_disable(struct cpuset *cs, struct tmpmasks *tmp)
        compute_excpus(cs, cs->effective_xcpus);
        reset_partition_data(cs);
        spin_unlock_irq(&callback_lock);
-       update_isolation_cpumasks();
        cpuset_force_rebuild();
 
        /*
@@ -1589,7 +1586,6 @@ static void remote_cpus_update(struct cpuset *cs, struct cpumask *xcpus,
        if (xcpus)
                cpumask_copy(cs->exclusive_cpus, xcpus);
        spin_unlock_irq(&callback_lock);
-       update_isolation_cpumasks();
        if (adding || deleting)
                cpuset_force_rebuild();
 
@@ -1933,7 +1929,6 @@ write_error:
                partition_xcpus_add(new_prs, parent, tmp->delmask);
 
        spin_unlock_irq(&callback_lock);
-       update_isolation_cpumasks();
 
        if ((old_prs != new_prs) && (cmd == partcmd_update))
                update_partition_exclusive_flag(cs, new_prs);
@@ -2901,7 +2896,6 @@ out:
        else if (isolcpus_updated)
                isolated_cpus_update(old_prs, new_prs, cs->effective_xcpus);
        spin_unlock_irq(&callback_lock);
-       update_isolation_cpumasks();
 
        /* Force update if switching back to member & update effective_xcpus */
        update_cpumasks_hier(cs, &tmpmask, !new_prs);
@@ -3191,9 +3185,8 @@ ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
        }
 
        free_cpuset(trialcs);
-       if (force_sd_rebuild)
-               rebuild_sched_domains_locked();
 out_unlock:
+       update_hk_sched_domains();
        cpuset_full_unlock();
        if (of_cft(of)->private == FILE_MEMLIST)
                schedule_flush_migrate_mm();
@@ -3301,6 +3294,7 @@ static ssize_t cpuset_partition_write(struct kernfs_open_file *of, char *buf,
        cpuset_full_lock();
        if (is_cpuset_online(cs))
                retval = update_prstate(cs, val);
+       update_hk_sched_domains();
        cpuset_full_unlock();
        return retval ?: nbytes;
 }
@@ -3475,6 +3469,7 @@ static void cpuset_css_killed(struct cgroup_subsys_state *css)
        /* Reset valid partition back to member */
        if (is_partition_valid(cs))
                update_prstate(cs, PRS_MEMBER);
+       update_hk_sched_domains();
        cpuset_full_unlock();
 }
 
@@ -3882,10 +3877,12 @@ static void cpuset_handle_hotplug(void)
                rcu_read_unlock();
        }
 
-       /* rebuild sched domains if necessary */
-       if (force_sd_rebuild)
-               rebuild_sched_domains_cpuslocked();
 
+       if (update_housekeeping || force_sd_rebuild) {
+               mutex_lock(&cpuset_mutex);
+               update_hk_sched_domains();
+               mutex_unlock(&cpuset_mutex);
+       }
        free_tmpmasks(ptmp);
 }