[PATCH 21/22 v2] staging/lustre/libcfs: Convert to hotplug state machine

From: Sebastian Andrzej Siewior
Date: Fri Dec 02 2016 - 05:18:40 EST


From: Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>

Install the callbacks via the state machine.
Cc: Oleg Drokin <oleg.drokin@xxxxxxxxx>
Cc: Andreas Dilger <andreas.dilger@xxxxxxxxx>
Cc: James Simmons <jsimmons@xxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: lustre-devel@xxxxxxxxxxxxxxxx
Cc: devel@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>
[bigeasy: rebase to linux-next]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
v1âv2: rebase to linux-next

Side note: Is there a reason the handle the down state very late at
CPU_DEAD time and use the counterpart of the online callback (the old
CPU_DOWN_PREPARE state).

.../staging/lustre/lnet/libcfs/linux/linux-cpu.c | 88 ++++++++++++----------
include/linux/cpuhotplug.h | 1 +
2 files changed, 49 insertions(+), 40 deletions(-)

diff --git a/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c b/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c
index 6b9cf06e8df2..f70b7d16378c 100644
--- a/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c
+++ b/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c
@@ -75,6 +75,9 @@ struct cfs_cpt_data {
};

static struct cfs_cpt_data cpt_data;
+#ifdef CONFIG_HOTPLUG_CPU
+static enum cpuhp_state lustre_cpu_online;
+#endif

static void
cfs_node_to_cpumask(int node, cpumask_t *mask)
@@ -967,48 +970,37 @@ cfs_cpt_table_create_pattern(char *pattern)
}

#ifdef CONFIG_HOTPLUG_CPU
-static int
-cfs_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
+static void cfs_cpu_incr_cpt_version(void)
{
- unsigned int cpu = (unsigned long)hcpu;
- bool warn;
-
- switch (action) {
- case CPU_DEAD:
- case CPU_DEAD_FROZEN:
- case CPU_ONLINE:
- case CPU_ONLINE_FROZEN:
- spin_lock(&cpt_data.cpt_lock);
- cpt_data.cpt_version++;
- spin_unlock(&cpt_data.cpt_lock);
- /* Fall through */
- default:
- if (action != CPU_DEAD && action != CPU_DEAD_FROZEN) {
- CDEBUG(D_INFO, "CPU changed [cpu %u action %lx]\n",
- cpu, action);
- break;
- }
-
- mutex_lock(&cpt_data.cpt_mutex);
- /* if all HTs in a core are offline, it may break affinity */
- cpumask_copy(cpt_data.cpt_cpumask,
- topology_sibling_cpumask(cpu));
- warn = cpumask_any_and(cpt_data.cpt_cpumask,
- cpu_online_mask) >= nr_cpu_ids;
- mutex_unlock(&cpt_data.cpt_mutex);
- CDEBUG(warn ? D_WARNING : D_INFO,
- "Lustre: can't support CPU plug-out well now, performance and stability could be impacted [CPU %u action: %lx]\n",
- cpu, action);
- }
-
- return NOTIFY_OK;
+ spin_lock(&cpt_data.cpt_lock);
+ cpt_data.cpt_version++;
+ spin_unlock(&cpt_data.cpt_lock);
}

-static struct notifier_block cfs_cpu_notifier = {
- .notifier_call = cfs_cpu_notify,
- .priority = 0
-};
+static int cfs_cpu_online(unsigned int cpu)
+{
+ cfs_cpu_incr_cpt_version();
+ return 0;
+}

+static int cfs_cpu_dead(unsigned int cpu)
+{
+ bool warn;
+
+ cfs_cpu_incr_cpt_version();
+
+ mutex_lock(&cpt_data.cpt_mutex);
+ /* if all HTs in a core are offline, it may break affinity */
+ cpumask_copy(cpt_data.cpt_cpumask,
+ topology_sibling_cpumask(cpu));
+ warn = cpumask_any_and(cpt_data.cpt_cpumask,
+ cpu_online_mask) >= nr_cpu_ids;
+ mutex_unlock(&cpt_data.cpt_mutex);
+ CDEBUG(warn ? D_WARNING : D_INFO,
+ "Lustre: can't support CPU plug-out well now, performance and stability could be impacted [CPU %u]\n",
+ cpu);
+ return 0;
+}
#endif

void
@@ -1018,7 +1010,9 @@ cfs_cpu_fini(void)
cfs_cpt_table_free(cfs_cpt_table);

#ifdef CONFIG_HOTPLUG_CPU
- unregister_hotcpu_notifier(&cfs_cpu_notifier);
+ if (lustre_cpu_online)
+ cpuhp_remove_state_nocalls(lustre_cpu_online);
+ cpuhp_remove_state_nocalls(CPUHP_LUSTRE_CFS_DEAD);
#endif
if (cpt_data.cpt_cpumask)
LIBCFS_FREE(cpt_data.cpt_cpumask, cpumask_size());
@@ -1027,6 +1021,10 @@ cfs_cpu_fini(void)
int
cfs_cpu_init(void)
{
+#ifdef CONFIG_HOTPLUG_CPU
+ int ret;
+#endif
+
LASSERT(!cfs_cpt_table);

memset(&cpt_data, 0, sizeof(cpt_data));
@@ -1041,7 +1039,17 @@ cfs_cpu_init(void)
mutex_init(&cpt_data.cpt_mutex);

#ifdef CONFIG_HOTPLUG_CPU
- register_hotcpu_notifier(&cfs_cpu_notifier);
+ ret = cpuhp_setup_state_nocalls(CPUHP_LUSTRE_CFS_DEAD,
+ "staging/lustre/cfe:dead", NULL,
+ cfs_cpu_dead);
+ if (ret < 0)
+ goto failed;
+ ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+ "staging/lustre/cfe:online",
+ cfs_cpu_online, NULL);
+ if (ret < 0)
+ goto failed;
+ lustre_cpu_online = ret;
#endif

if (*cpu_pattern) {
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 22acee76cf4c..141c3be242d1 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -41,6 +41,7 @@ enum cpuhp_state {
CPUHP_NET_DEV_DEAD,
CPUHP_PCI_XGENE_DEAD,
CPUHP_IOMMU_INTEL_DEAD,
+ CPUHP_LUSTRE_CFS_DEAD,
CPUHP_WORKQUEUE_PREP,
CPUHP_POWER_NUMA_PREPARE,
CPUHP_HRTIMERS_PREPARE,
--
2.10.2