powercap/intel_rapl: Track active CPUs internally

The ability of the CPU hotplug code to stop online/offline at each step
makes it necessary to track the activated CPUs in a package directly,
because outerwise a CPU offline callback can find CPUs which have already
executed the offline callback, but are not yet marked offline in the
topology mask. That could make such a CPU the package leader and in case
that CPU goes fully offline leave the package lead orphaned.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
index 76a0069..65ed88a 100644 (file)
--- a/drivers/powercap/intel_rapl.c
+++ b/drivers/powercap/intel_rapl.c
@@ -189,14 +189,13 @@ struct rapl_package {
        unsigned int time_unit;
        struct rapl_domain *domains; /* array of domains, sized at runtime */
        struct powercap_zone *power_zone; /* keep track of parent zone */
-       int nr_cpus; /* active cpus on the package, topology info is lost during
-                     * cpu hotplug. so we have to track ourselves.
-                     */
        unsigned long power_limit_irq; /* keep track of package power limit
                                        * notify interrupt enable status.
                                        */
        struct list_head plist;
        int lead_cpu; /* one active cpu per package for access */
+       /* Track active cpus */
+       struct cpumask cpumask;
 };
 
 struct rapl_defaults {
@@ -1432,19 +1431,17 @@ static void rapl_remove_package(struct rapl_package *rp)
 }
 
 /* called from CPU hotplug notifier, hotplug lock held */
-static int rapl_add_package(int cpu)
+static struct rapl_package *rapl_add_package(int cpu, int pkgid)
 {
        struct rapl_package *rp;
-       int ret, phy_package_id;
+       int ret;
 
-       phy_package_id = topology_physical_package_id(cpu);
        rp = kzalloc(sizeof(struct rapl_package), GFP_KERNEL);
        if (!rp)
-               return -ENOMEM;
+               return ERR_PTR(-ENOMEM);
 
        /* add the new package to the list */
-       rp->id = phy_package_id;
-       rp->nr_cpus = 1;
+       rp->id = pkgid;
        rp->lead_cpu = cpu;
 
        /* check if the package contains valid domains */
@@ -1457,14 +1454,13 @@ static int rapl_add_package(int cpu)
        if (!ret) {
                INIT_LIST_HEAD(&rp->plist);
                list_add(&rp->plist, &rapl_packages);
-               return 0;
+               return rp;
        }
 
 err_free_package:
        kfree(rp->domains);
        kfree(rp);
-
-       return ret;
+       return ERR_PTR(ret);
 }
 
 /* Handles CPU hotplug on multi-socket systems.
@@ -1476,42 +1472,35 @@ err_free_package:
  */
 static int rapl_cpu_online(unsigned int cpu)
 {
+       int pkgid = topology_physical_package_id(cpu);
        struct rapl_package *rp;
-       int phy_package_id;
-
-       phy_package_id = topology_physical_package_id(cpu);
 
-       rp = find_package_by_id(phy_package_id);
-       if (rp) {
-               rp->nr_cpus++;
-               return 0;
+       rp = find_package_by_id(pkgid);
+       if (!rp) {
+               rp = rapl_add_package(cpu, pkgid);
+               if (IS_ERR(rp))
+                       return PTR_ERR(rp);
        }
-       return rapl_add_package(cpu);
+       cpumask_set_cpu(cpu, &rp->cpumask);
+       return 0;
 }
 
 static int rapl_cpu_down_prep(unsigned int cpu)
 {
-       int phy_package_id;
+       int pkgid = topology_physical_package_id(cpu);
        struct rapl_package *rp;
        int lead_cpu;
 
-       phy_package_id = topology_physical_package_id(cpu);
-       rp = find_package_by_id(phy_package_id);
+       rp = find_package_by_id(pkgid);
        if (!rp)
                return 0;
-       if (--rp->nr_cpus == 0) {
+
+       cpumask_clear_cpu(cpu, &rp->cpumask);
+       lead_cpu = cpumask_first(&rp->cpumask);
+       if (lead_cpu >= nr_cpu_ids)
                rapl_remove_package(rp);
-       } else if (cpu == rp->lead_cpu) {
-               /* choose another active cpu in the package */
-               lead_cpu = cpumask_any_but(topology_core_cpumask(cpu), cpu);
-               if (lead_cpu < nr_cpu_ids) {
-                       rp->lead_cpu = lead_cpu;
-               } else {
-                       /* should never go here */
-                       pr_err("no active cpu available for package %d\n",
-                              phy_package_id);
-               }
-       }
+       else if (rp->lead_cpu == cpu)
+               rp->lead_cpu = lead_cpu;
        return 0;
 }