1 files changed, 242 insertions, 0 deletions

diff --git a/kernel/rtmutex-debug.c b/kernel/rtmutex-debug.c
new file mode 100644
index 000000000000..0c1faa950af7
--- /dev/null
+++ b/kernel/rtmutex-debug.c
@@ -0,0 +1,242 @@
+/*
+ * RT-Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This code is based on the rt.c implementation in the preempt-rt tree.
+ * Portions of said code are
+ *
+ *  Copyright (C) 2004  LynuxWorks, Inc., Igor Manyilov, Bill Huey
+ *  Copyright (C) 2006  Esben Nielsen
+ *  Copyright (C) 2006  Kihon Technologies Inc.,
+ *                      Steven Rostedt <rostedt@goodmis.org>
+ *
+ * See rt.c in preempt-rt for proper credits and further information
+ */
+#include <linux/config.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/kallsyms.h>
+#include <linux/syscalls.h>
+#include <linux/interrupt.h>
+#include <linux/plist.h>
+#include <linux/fs.h>
+#include <linux/debug_locks.h>
+
+#include "rtmutex_common.h"
+
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+# include "rtmutex-debug.h"
+#else
+# include "rtmutex.h"
+#endif
+
+# define TRACE_WARN_ON(x)                       WARN_ON(x)
+# define TRACE_BUG_ON(x)                        BUG_ON(x)
+
+# define TRACE_OFF()                                            \
+do {                                                            \
+        if (rt_trace_on) {                                      \
+                rt_trace_on = 0;                                \
+                console_verbose();                              \
+                if (spin_is_locked(&current->pi_lock))          \
+                        spin_unlock(&current->pi_lock);         \
+        }                                                       \
+} while (0)
+
+# define TRACE_OFF_NOLOCK()                                     \
+do {                                                            \
+        if (rt_trace_on) {                                      \
+                rt_trace_on = 0;                                \
+                console_verbose();                              \
+        }                                                       \
+} while (0)
+
+# define TRACE_BUG_LOCKED()                     \
+do {                                            \
+        TRACE_OFF();                            \
+        BUG();                                  \
+} while (0)
+
+# define TRACE_WARN_ON_LOCKED(c)                \
+do {                                            \
+        if (unlikely(c)) {                      \
+                TRACE_OFF();                    \
+                WARN_ON(1);                     \
+        }                                       \
+} while (0)
+
+# define TRACE_BUG_ON_LOCKED(c)                 \
+do {                                            \
+        if (unlikely(c))                        \
+                TRACE_BUG_LOCKED();             \
+} while (0)
+
+#ifdef CONFIG_SMP
+# define SMP_TRACE_BUG_ON_LOCKED(c)     TRACE_BUG_ON_LOCKED(c)
+#else
+# define SMP_TRACE_BUG_ON_LOCKED(c)     do { } while (0)
+#endif
+
+/*
+ * deadlock detection flag. We turn it off when we detect
+ * the first problem because we dont want to recurse back
+ * into the tracing code when doing error printk or
+ * executing a BUG():
+ */
+int rt_trace_on = 1;
+
+void deadlock_trace_off(void)
+{
+        rt_trace_on = 0;
+}
+
+static void printk_task(struct task_struct *p)
+{
+        if (p)
+                printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
+        else
+                printk("<none>");
+}
+
+static void printk_lock(struct rt_mutex *lock, int print_owner)
+{
+        if (lock->name)
+                printk(" [%p] {%s}\n",
+                        lock, lock->name);
+        else
+                printk(" [%p] {%s:%d}\n",
+                        lock, lock->file, lock->line);
+
+        if (print_owner && rt_mutex_owner(lock)) {
+                printk(".. ->owner: %p\n", lock->owner);
+                printk(".. held by:  ");
+                printk_task(rt_mutex_owner(lock));
+                printk("\n");
+        }
+}
+
+void rt_mutex_debug_task_free(struct task_struct *task)
+{
+        WARN_ON(!plist_head_empty(&task->pi_waiters));
+        WARN_ON(task->pi_blocked_on);
+}
+
+/*
+ * We fill out the fields in the waiter to store the information about
+ * the deadlock. We print when we return. act_waiter can be NULL in
+ * case of a remove waiter operation.
+ */
+void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
+                             struct rt_mutex *lock)
+{
+        struct task_struct *task;
+
+        if (!rt_trace_on || detect || !act_waiter)
+                return;
+
+        task = rt_mutex_owner(act_waiter->lock);
+        if (task && task != current) {
+                act_waiter->deadlock_task_pid = task->pid;
+                act_waiter->deadlock_lock = lock;
+        }
+}
+
+void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
+{
+        struct task_struct *task;
+
+        if (!waiter->deadlock_lock || !rt_trace_on)
+                return;
+
+        task = find_task_by_pid(waiter->deadlock_task_pid);
+        if (!task)
+                return;
+
+        TRACE_OFF_NOLOCK();
+
+        printk("\n============================================\n");
+        printk(  "[ BUG: circular locking deadlock detected! ]\n");
+        printk(  "--------------------------------------------\n");
+        printk("%s/%d is deadlocking current task %s/%d\n\n",
+               task->comm, task->pid, current->comm, current->pid);
+
+        printk("\n1) %s/%d is trying to acquire this lock:\n",
+               current->comm, current->pid);
+        printk_lock(waiter->lock, 1);
+
+        printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
+        printk_lock(waiter->deadlock_lock, 1);
+
+        debug_show_held_locks(current);
+        debug_show_held_locks(task);
+
+        printk("\n%s/%d's [blocked] stackdump:\n\n", task->comm, task->pid);
+        show_stack(task, NULL);
+        printk("\n%s/%d's [current] stackdump:\n\n",
+               current->comm, current->pid);
+        dump_stack();
+        debug_show_all_locks();
+
+        printk("[ turning off deadlock detection."
+               "Please report this trace. ]\n\n");
+        local_irq_disable();
+}
+
+void debug_rt_mutex_lock(struct rt_mutex *lock)
+{
+}
+
+void debug_rt_mutex_unlock(struct rt_mutex *lock)
+{
+        TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
+}
+
+void
+debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
+{
+}
+
+void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
+{
+        TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
+}
+
+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);
+}
+
+void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
+{
+        TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
+        TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
+        TRACE_WARN_ON(waiter->task);
+        memset(waiter, 0x22, sizeof(*waiter));
+}
+
+void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
+{
+        /*
+         * Make sure we are not reinitializing a held lock:
+         */
+        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+        lock->name = name;
+}
+
+void
+rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
+{
+}
+
+void rt_mutex_deadlock_account_unlock(struct task_struct *task)
+{
+}
+