CPU hotplug: Add lockdep annotations to get/put_online_cpus()

Add lockdep annotations for get/put_online_cpus() and
cpu_hotplug_begin()/cpu_hotplug_end().

Cc: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index deff2e693766..33caf5e97701 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -19,6 +19,7 @@
 #include <linux/mutex.h>
 #include <linux/gfp.h>
 #include <linux/suspend.h>
+#include <linux/lockdep.h>
 
 #include "smpboot.h"
 
@@ -57,17 +58,30 @@ static struct {
          * an ongoing cpu hotplug operation.
          */
         int refcount;
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        struct lockdep_map dep_map;
+#endif
 } cpu_hotplug = {
         .active_writer = NULL,
         .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
         .refcount = 0,
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        .dep_map = {.name = "cpu_hotplug.lock" },
+#endif
 };
 
+/* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
+#define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
+#define cpuhp_lock_acquire()      lock_map_acquire(&cpu_hotplug.dep_map)
+#define cpuhp_lock_release()      lock_map_release(&cpu_hotplug.dep_map)
+
 void get_online_cpus(void)
 {
         might_sleep();
         if (cpu_hotplug.active_writer == current)
                 return;
+        cpuhp_lock_acquire_read();
         mutex_lock(&cpu_hotplug.lock);
         cpu_hotplug.refcount++;
         mutex_unlock(&cpu_hotplug.lock);
@@ -87,6 +101,7 @@ void put_online_cpus(void)
         if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
                 wake_up_process(cpu_hotplug.active_writer);
         mutex_unlock(&cpu_hotplug.lock);
+        cpuhp_lock_release();
 
 }
 EXPORT_SYMBOL_GPL(put_online_cpus);
@@ -117,6 +132,7 @@ void cpu_hotplug_begin(void)
 {
         cpu_hotplug.active_writer = current;
 
+        cpuhp_lock_acquire();
         for (;;) {
                 mutex_lock(&cpu_hotplug.lock);
                 if (likely(!cpu_hotplug.refcount))
@@ -131,6 +147,7 @@ void cpu_hotplug_done(void)
 {
         cpu_hotplug.active_writer = NULL;
         mutex_unlock(&cpu_hotplug.lock);
+        cpuhp_lock_release();
 }
 
 /*