PM: Lock PM device list mutex in show_dev_hash()

Lock the PM device list mutex using device_pm_lock() and
device_pm_unlock() around the list iteration in show_dev_hash().

show_dev_hash() was reverse iterating dpm_list without first locking the
mutex that the functions in drivers/base/power/main.c lock. I assume
this was unintentional since there is no comment suggesting why the lock
might not be necessary.

Signed-off-by: James Hogan <james@albanarts.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c
index 0a1a2c4dbc6e..17e24e3f4422 100644
--- a/drivers/base/power/trace.c
+++ b/drivers/base/power/trace.c
@@ -188,8 +188,10 @@ static int show_file_hash(unsigned int value)
 static int show_dev_hash(unsigned int value)
 {
         int match = 0;
-        struct list_head *entry = dpm_list.prev;
+        struct list_head *entry;
 
+        device_pm_lock();
+        entry = dpm_list.prev;
         while (entry != &dpm_list) {
                 struct device * dev = to_device(entry);
                 unsigned int hash = hash_string(DEVSEED, dev_name(dev), DEVHASH);
@@ -199,6 +201,7 @@ static int show_dev_hash(unsigned int value)
                 }
                 entry = entry->prev;
         }
+        device_pm_unlock();
         return match;
 }