Don't operate with pid_t in rtmutex tester

The proper behavior to store task's pid and get this task later is to get the
struct pid pointer and get the task with the pid_task() call.

Make it for rt_mutex_waiter->deadlock_task_pid field.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 10 insertions, 4 deletions

diff --git a/kernel/rtmutex-debug.c b/kernel/rtmutex-debug.c
index 56d73cb8826d..5fcb4fe645e2 100644
--- a/kernel/rtmutex-debug.c
+++ b/kernel/rtmutex-debug.c
@@ -130,7 +130,7 @@ void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
 
         task = rt_mutex_owner(act_waiter->lock);
         if (task && task != current) {
-                act_waiter->deadlock_task_pid = task->pid;
+                act_waiter->deadlock_task_pid = get_pid(task_pid(task));
                 act_waiter->deadlock_lock = lock;
         }
 }
@@ -142,9 +142,12 @@ void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
         if (!waiter->deadlock_lock || !rt_trace_on)
                 return;
 
-        task = find_task_by_pid(waiter->deadlock_task_pid);
-        if (!task)
+        rcu_read_lock();
+        task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
+        if (!task) {
+                rcu_read_unlock();
                 return;
+        }
 
         TRACE_OFF_NOLOCK();
 
@@ -173,6 +176,7 @@ void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
                 current->comm, task_pid_nr(current));
         dump_stack();
         debug_show_all_locks();
+        rcu_read_unlock();
 
         printk("[ turning off deadlock detection."
                "Please report this trace. ]\n\n");
@@ -203,10 +207,12 @@ void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
         memset(waiter, 0x11, sizeof(*waiter));
         plist_node_init(&waiter->list_entry, MAX_PRIO);
         plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
+        waiter->deadlock_task_pid = NULL;
 }
 
 void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
 {
+        put_pid(waiter->deadlock_task_pid);
         TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
         TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
         TRACE_WARN_ON(waiter->task);
diff --git a/kernel/rtmutex_common.h b/kernel/rtmutex_common.h
index 2d3b83593ca3..e124bf5800ea 100644
--- a/kernel/rtmutex_common.h
+++ b/kernel/rtmutex_common.h
@@ -51,7 +51,7 @@ struct rt_mutex_waiter {
         struct rt_mutex         *lock;
 #ifdef CONFIG_DEBUG_RT_MUTEXES
         unsigned long           ip;
-        pid_t                   deadlock_task_pid;
+        struct pid              *deadlock_task_pid;
         struct rt_mutex         *deadlock_lock;
 #endif
 };