17 files changed, 189 insertions, 79 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 170a9213c1b6..e4791b3ba55d 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -51,6 +51,7 @@ obj-$(CONFIG_UID16) += uid16.o
 obj-$(CONFIG_MODULES) += module.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
 obj-$(CONFIG_PM) += power/
+obj-$(CONFIG_FREEZER) += power/
 obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
 obj-$(CONFIG_KEXEC) += kexec.o
 obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e14db9c089b9..9edb5c4b79b4 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1122,8 +1122,8 @@ static void cgroup_kill_sb(struct super_block *sb) {
 
         mutex_unlock(&cgroup_mutex);
 
-        kfree(root);
         kill_litter_super(sb);
+        kfree(root);
 }
 
 static struct file_system_type cgroup_fs_type = {
diff --git a/kernel/futex.c b/kernel/futex.c
index f89d373a9c6d..438701adce23 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1165,6 +1165,7 @@ static int futex_wait(u32 __user *uaddr, int fshared,
                       u32 val, ktime_t *abs_time, u32 bitset, int clockrt)
 {
         struct task_struct *curr = current;
+        struct restart_block *restart;
         DECLARE_WAITQUEUE(wait, curr);
         struct futex_hash_bucket *hb;
         struct futex_q q;
@@ -1216,11 +1217,13 @@ retry:
 
                 if (!ret)
                         goto retry;
-                return ret;
+                goto out;
         }
         ret = -EWOULDBLOCK;
-        if (uval != val)
-                goto out_unlock_put_key;
+        if (unlikely(uval != val)) {
+                queue_unlock(&q, hb);
+                goto out_put_key;
+        }
 
         /* Only actually queue if *uaddr contained val.  */
         queue_me(&q, hb);
@@ -1284,38 +1287,38 @@ retry:
          */
 
         /* If we were woken (and unqueued), we succeeded, whatever. */
+        ret = 0;
         if (!unqueue_me(&q))
-                return 0;
+                goto out_put_key;
+        ret = -ETIMEDOUT;
         if (rem)
-                return -ETIMEDOUT;
+                goto out_put_key;
 
         /*
          * We expect signal_pending(current), but another thread may
          * have handled it for us already.
          */
+        ret = -ERESTARTSYS;
         if (!abs_time)
-                return -ERESTARTSYS;
-        else {
-                struct restart_block *restart;
-                restart = &current_thread_info()->restart_block;
-                restart->fn = futex_wait_restart;
-                restart->futex.uaddr = (u32 *)uaddr;
-                restart->futex.val = val;
-                restart->futex.time = abs_time->tv64;
-                restart->futex.bitset = bitset;
-                restart->futex.flags = 0;
-
-                if (fshared)
-                        restart->futex.flags |= FLAGS_SHARED;
-                if (clockrt)
-                        restart->futex.flags |= FLAGS_CLOCKRT;
-                return -ERESTART_RESTARTBLOCK;
-        }
+                goto out_put_key;
 
-out_unlock_put_key:
-        queue_unlock(&q, hb);
-        put_futex_key(fshared, &q.key);
+        restart = &current_thread_info()->restart_block;
+        restart->fn = futex_wait_restart;
+        restart->futex.uaddr = (u32 *)uaddr;
+        restart->futex.val = val;
+        restart->futex.time = abs_time->tv64;
+        restart->futex.bitset = bitset;
+        restart->futex.flags = 0;
+
+        if (fshared)
+                restart->futex.flags |= FLAGS_SHARED;
+        if (clockrt)
+                restart->futex.flags |= FLAGS_CLOCKRT;
 
+        ret = -ERESTART_RESTARTBLOCK;
+
+out_put_key:
+        put_futex_key(fshared, &q.key);
 out:
         return ret;
 }
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 795e7b67a228..c7fd6692939d 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1465,6 +1465,11 @@ int kernel_kexec(void)
                 error = device_power_down(PMSG_FREEZE);
                 if (error)
                         goto Enable_irqs;
+
+                /* Suspend system devices */
+                error = sysdev_suspend(PMSG_FREEZE);
+                if (error)
+                        goto Power_up_devices;
         } else
 #endif
         {
@@ -1477,6 +1482,8 @@ int kernel_kexec(void)
 
 #ifdef CONFIG_KEXEC_JUMP
         if (kexec_image->preserve_context) {
+                sysdev_resume();
+ Power_up_devices:
                 device_power_up(PMSG_RESTORE);
  Enable_irqs:
                 local_irq_enable();
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 2313a4cc14ea..e976e505648d 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -681,6 +681,33 @@ static void cpu_timer_fire(struct k_itimer *timer)
 }
 
 /*
+ * Sample a process (thread group) timer for the given group_leader task.
+ * Must be called with tasklist_lock held for reading.
+ */
+static int cpu_timer_sample_group(const clockid_t which_clock,
+                                  struct task_struct *p,
+                                  union cpu_time_count *cpu)
+{
+        struct task_cputime cputime;
+
+        thread_group_cputimer(p, &cputime);
+        switch (CPUCLOCK_WHICH(which_clock)) {
+        default:
+                return -EINVAL;
+        case CPUCLOCK_PROF:
+                cpu->cpu = cputime_add(cputime.utime, cputime.stime);
+                break;
+        case CPUCLOCK_VIRT:
+                cpu->cpu = cputime.utime;
+                break;
+        case CPUCLOCK_SCHED:
+                cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
+                break;
+        }
+        return 0;
+}
+
+/*
  * Guts of sys_timer_settime for CPU timers.
  * This is called with the timer locked and interrupts disabled.
  * If we return TIMER_RETRY, it's necessary to release the timer's lock
@@ -741,7 +768,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
                 cpu_clock_sample(timer->it_clock, p, &val);
         } else {
-                cpu_clock_sample_group(timer->it_clock, p, &val);
+                cpu_timer_sample_group(timer->it_clock, p, &val);
         }
 
         if (old) {
@@ -889,7 +916,7 @@ void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
                         read_unlock(&tasklist_lock);
                         goto dead;
                 } else {
-                        cpu_clock_sample_group(timer->it_clock, p, &now);
+                        cpu_timer_sample_group(timer->it_clock, p, &now);
                         clear_dead = (unlikely(p->exit_state) &&
                                       thread_group_empty(p));
                 }
@@ -1244,7 +1271,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
                         clear_dead_task(timer, now);
                         goto out_unlock;
                 }
-                cpu_clock_sample_group(timer->it_clock, p, &now);
+                cpu_timer_sample_group(timer->it_clock, p, &now);
                 bump_cpu_timer(timer, now);
                 /* Leave the tasklist_lock locked for the call below.  */
         }
@@ -1409,33 +1436,6 @@ void run_posix_cpu_timers(struct task_struct *tsk)
 }
 
 /*
- * Sample a process (thread group) timer for the given group_leader task.
- * Must be called with tasklist_lock held for reading.
- */
-static int cpu_timer_sample_group(const clockid_t which_clock,
-                                  struct task_struct *p,
-                                  union cpu_time_count *cpu)
-{
-        struct task_cputime cputime;
-
-        thread_group_cputimer(p, &cputime);
-        switch (CPUCLOCK_WHICH(which_clock)) {
-        default:
-                return -EINVAL;
-        case CPUCLOCK_PROF:
-                cpu->cpu = cputime_add(cputime.utime, cputime.stime);
-                break;
-        case CPUCLOCK_VIRT:
-                cpu->cpu = cputime.utime;
-                break;
-        case CPUCLOCK_SCHED:
-                cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
-                break;
-        }
-        return 0;
-}
-
-/*
  * Set one of the process-wide special case CPU timers.
  * The tsk->sighand->siglock must be held by the caller.
  * The *newval argument is relative and we update it to be absolute, *oldval
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index d7a10167a25b..720ea4f781bd 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -3,7 +3,7 @@ ifeq ($(CONFIG_PM_DEBUG),y)
 EXTRA_CFLAGS    +=      -DDEBUG
 endif
 
-obj-y                           := main.o
+obj-$(CONFIG_PM)                += main.o
 obj-$(CONFIG_PM_SLEEP)          += console.o
 obj-$(CONFIG_FREEZER)           += process.o
 obj-$(CONFIG_HIBERNATION)       += swsusp.o disk.o snapshot.o swap.o user.o
diff --git a/kernel/power/console.c b/kernel/power/console.c
index b8628be2a465..a3961b205de7 100644
--- a/kernel/power/console.c
+++ b/kernel/power/console.c
@@ -78,6 +78,12 @@ void pm_restore_console(void)
         }
         set_console(orig_fgconsole);
         release_console_sem();
+
+        if (vt_waitactive(orig_fgconsole)) {
+                pr_debug("Resume: Can't switch VCs.");
+                return;
+        }
+
         kmsg_redirect = orig_kmsg;
 }
 #endif
diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index 432ee575c9ee..4a4a206b1979 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -227,6 +227,12 @@ static int create_image(int platform_mode)
                         "aborting hibernation\n");
                 goto Enable_irqs;
         }
+        sysdev_suspend(PMSG_FREEZE);
+        if (error) {
+                printk(KERN_ERR "PM: Some devices failed to power down, "
+                        "aborting hibernation\n");
+                goto Power_up_devices;
+        }
 
         if (hibernation_test(TEST_CORE))
                 goto Power_up;
@@ -242,9 +248,11 @@ static int create_image(int platform_mode)
         if (!in_suspend)
                 platform_leave(platform_mode);
  Power_up:
+        sysdev_resume();
         /* NOTE:  device_power_up() is just a resume() for devices
          * that suspended with irqs off ... no overall powerup.
          */
+ Power_up_devices:
         device_power_up(in_suspend ?
                 (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
  Enable_irqs:
@@ -335,6 +343,7 @@ static int resume_target_kernel(void)
                         "aborting resume\n");
                 goto Enable_irqs;
         }
+        sysdev_suspend(PMSG_QUIESCE);
         /* We'll ignore saved state, but this gets preempt count (etc) right */
         save_processor_state();
         error = restore_highmem();
@@ -357,6 +366,7 @@ static int resume_target_kernel(void)
         swsusp_free();
         restore_processor_state();
         touch_softlockup_watchdog();
+        sysdev_resume();
         device_power_up(PMSG_RECOVER);
  Enable_irqs:
         local_irq_enable();
@@ -440,6 +450,7 @@ int hibernation_platform_enter(void)
         local_irq_disable();
         error = device_power_down(PMSG_HIBERNATE);
         if (!error) {
+                sysdev_suspend(PMSG_HIBERNATE);
                 hibernation_ops->enter();
                 /* We should never get here */
                 while (1);
@@ -595,6 +606,12 @@ static int software_resume(void)
         unsigned int flags;
 
         /*
+         * If the user said "noresume".. bail out early.
+         */
+        if (noresume)
+                return 0;
+
+        /*
          * name_to_dev_t() below takes a sysfs buffer mutex when sysfs
          * is configured into the kernel. Since the regular hibernate
          * trigger path is via sysfs which takes a buffer mutex before
@@ -610,6 +627,11 @@ static int software_resume(void)
                         mutex_unlock(&pm_mutex);
                         return -ENOENT;
                 }
+                /*
+                 * Some device discovery might still be in progress; we need
+                 * to wait for this to finish.
+                 */
+                wait_for_device_probe();
                 swsusp_resume_device = name_to_dev_t(resume_file);
                 pr_debug("PM: Resume from partition %s\n", resume_file);
         } else {
diff --git a/kernel/power/main.c b/kernel/power/main.c
index b4d219016b6c..c9632f841f64 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -298,8 +298,12 @@ static int suspend_enter(suspend_state_t state)
                 goto Done;
         }
 
-        if (!suspend_test(TEST_CORE))
-                error = suspend_ops->enter(state);
+        error = sysdev_suspend(PMSG_SUSPEND);
+        if (!error) {
+                if (!suspend_test(TEST_CORE))
+                        error = suspend_ops->enter(state);
+                sysdev_resume();
+        }
 
         device_power_up(PMSG_RESUME);
  Done:
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 6da14358537c..505f319e489c 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -60,6 +60,7 @@ static struct block_device *resume_bdev;
 static int submit(int rw, pgoff_t page_off, struct page *page,
                         struct bio **bio_chain)
 {
+        const int bio_rw = rw | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG);
         struct bio *bio;
 
         bio = bio_alloc(__GFP_WAIT | __GFP_HIGH, 1);
@@ -80,7 +81,7 @@ static int submit(int rw, pgoff_t page_off, struct page *page,
         bio_get(bio);
 
         if (bio_chain == NULL) {
-                submit_bio(rw | (1 << BIO_RW_SYNC), bio);
+                submit_bio(bio_rw, bio);
                 wait_on_page_locked(page);
                 if (rw == READ)
                         bio_set_pages_dirty(bio);
@@ -90,7 +91,7 @@ static int submit(int rw, pgoff_t page_off, struct page *page,
                         get_page(page); /* These pages are freed later */
                 bio->bi_private = *bio_chain;
                 *bio_chain = bio;
-                submit_bio(rw | (1 << BIO_RW_SYNC), bio);
+                submit_bio(bio_rw, bio);
         }
         return 0;
 }
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 005b93d839ba..6c85359364f2 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -95,15 +95,15 @@ static int snapshot_open(struct inode *inode, struct file *filp)
                 data->swap = swsusp_resume_device ?
                         swap_type_of(swsusp_resume_device, 0, NULL) : -1;
                 data->mode = O_RDONLY;
-                error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
+                error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
                 if (error)
-                        pm_notifier_call_chain(PM_POST_RESTORE);
+                        pm_notifier_call_chain(PM_POST_HIBERNATION);
         } else {
                 data->swap = -1;
                 data->mode = O_WRONLY;
-                error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
+                error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
                 if (error)
-                        pm_notifier_call_chain(PM_POST_HIBERNATION);
+                        pm_notifier_call_chain(PM_POST_RESTORE);
         }
         if (error)
                 atomic_inc(&snapshot_device_available);
diff --git a/kernel/printk.c b/kernel/printk.c
index 69188f226a93..e3602d0755b0 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -73,7 +73,6 @@ EXPORT_SYMBOL(oops_in_progress);
  * driver system.
  */
 static DECLARE_MUTEX(console_sem);
-static DECLARE_MUTEX(secondary_console_sem);
 struct console *console_drivers;
 EXPORT_SYMBOL_GPL(console_drivers);
 
@@ -891,12 +890,14 @@ void suspend_console(void)
         printk("Suspending console(s) (use no_console_suspend to debug)\n");
         acquire_console_sem();
         console_suspended = 1;
+        up(&console_sem);
 }
 
 void resume_console(void)
 {
         if (!console_suspend_enabled)
                 return;
+        down(&console_sem);
         console_suspended = 0;
         release_console_sem();
 }
@@ -912,11 +913,9 @@ void resume_console(void)
 void acquire_console_sem(void)
 {
         BUG_ON(in_interrupt());
-        if (console_suspended) {
-                down(&secondary_console_sem);
-                return;
-        }
         down(&console_sem);
+        if (console_suspended)
+                return;
         console_locked = 1;
         console_may_schedule = 1;
 }
@@ -926,6 +925,10 @@ int try_acquire_console_sem(void)
 {
         if (down_trylock(&console_sem))
                 return -1;
+        if (console_suspended) {
+                up(&console_sem);
+                return -1;
+        }
         console_locked = 1;
         console_may_schedule = 0;
         return 0;
@@ -979,7 +982,7 @@ void release_console_sem(void)
         unsigned wake_klogd = 0;
 
         if (console_suspended) {
-                up(&secondary_console_sem);
+                up(&console_sem);
                 return;
         }
 
diff --git a/kernel/sched.c b/kernel/sched.c
index 61245b8d0f16..7d97ff7c4478 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6939,20 +6939,26 @@ static void free_rootdomain(struct root_domain *rd)
 
 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
 {
+        struct root_domain *old_rd = NULL;
         unsigned long flags;
 
         spin_lock_irqsave(&rq->lock, flags);
 
         if (rq->rd) {
-                struct root_domain *old_rd = rq->rd;
+                old_rd = rq->rd;
 
                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
                         set_rq_offline(rq);
 
                 cpumask_clear_cpu(rq->cpu, old_rd->span);
 
-                if (atomic_dec_and_test(&old_rd->refcount))
-                        free_rootdomain(old_rd);
+                /*
+                 * If we dont want to free the old_rt yet then
+                 * set old_rd to NULL to skip the freeing later
+                 * in this function:
+                 */
+                if (!atomic_dec_and_test(&old_rd->refcount))
+                        old_rd = NULL;
         }
 
         atomic_inc(&rd->refcount);
@@ -6963,6 +6969,9 @@ static void rq_attach_root(struct rq *rq, struct root_domain *rd)
                 set_rq_online(rq);
 
         spin_unlock_irqrestore(&rq->lock, flags);
+
+        if (old_rd)
+                free_rootdomain(old_rd);
 }
 
 static int __init_refok init_rootdomain(struct root_domain *rd, bool bootmem)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index e2a4ff6fc3a6..34e707e5ab87 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -52,6 +52,7 @@ config FUNCTION_TRACER
         depends on HAVE_FUNCTION_TRACER
         depends on DEBUG_KERNEL
         select FRAME_POINTER
+        select KALLSYMS
         select TRACING
         select CONTEXT_SWITCH_TRACER
         help
@@ -238,6 +239,7 @@ config STACK_TRACER
         depends on DEBUG_KERNEL
         select FUNCTION_TRACER
         select STACKTRACE
+        select KALLSYMS
         help
           This special tracer records the maximum stack footprint of the
           kernel and displays it in debugfs/tracing/stack_trace.
@@ -302,4 +304,27 @@ config FTRACE_STARTUP_TEST
           functioning properly. It will do tests on all the configured
           tracers of ftrace.
 
+config MMIOTRACE
+        bool "Memory mapped IO tracing"
+        depends on HAVE_MMIOTRACE_SUPPORT && DEBUG_KERNEL && PCI
+        select TRACING
+        help
+          Mmiotrace traces Memory Mapped I/O access and is meant for
+          debugging and reverse engineering. It is called from the ioremap
+          implementation and works via page faults. Tracing is disabled by
+          default and can be enabled at run-time.
+
+          See Documentation/tracers/mmiotrace.txt.
+          If you are not helping to develop drivers, say N.
+
+config MMIOTRACE_TEST
+        tristate "Test module for mmiotrace"
+        depends on MMIOTRACE && m
+        help
+          This is a dumb module for testing mmiotrace. It is very dangerous
+          as it will write garbage to IO memory starting at a given address.
+          However, it should be safe to use on e.g. unused portion of VRAM.
+
+          Say N, unless you absolutely know what you are doing.
+
 endmenu
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9a236ffe2aa4..fdf913dfc7e8 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2033,7 +2033,7 @@ free:
 static int start_graph_tracing(void)
 {
         struct ftrace_ret_stack **ret_stack_list;
-        int ret;
+        int ret, cpu;
 
         ret_stack_list = kmalloc(FTRACE_RETSTACK_ALLOC_SIZE *
                                 sizeof(struct ftrace_ret_stack *),
@@ -2042,6 +2042,10 @@ static int start_graph_tracing(void)
         if (!ret_stack_list)
                 return -ENOMEM;
 
+        /* The cpu_boot init_task->ret_stack will never be freed */
+        for_each_online_cpu(cpu)
+                ftrace_graph_init_task(idle_task(cpu));
+
         do {
                 ret = alloc_retstack_tasklist(ret_stack_list);
         } while (ret == -EAGAIN);
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index fffcb069f1dc..80e503ef6136 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -9,6 +9,7 @@
 #include <linux/kernel.h>
 #include <linux/mmiotrace.h>
 #include <linux/pci.h>
+#include <asm/atomic.h>
 
 #include "trace.h"
 
@@ -19,6 +20,7 @@ struct header_iter {
 static struct trace_array *mmio_trace_array;
 static bool overrun_detected;
 static unsigned long prev_overruns;
+static atomic_t dropped_count;
 
 static void mmio_reset_data(struct trace_array *tr)
 {
@@ -121,11 +123,11 @@ static void mmio_close(struct trace_iterator *iter)
 
 static unsigned long count_overruns(struct trace_iterator *iter)
 {
-        unsigned long cnt = 0;
+        unsigned long cnt = atomic_xchg(&dropped_count, 0);
         unsigned long over = ring_buffer_overruns(iter->tr->buffer);
 
         if (over > prev_overruns)
-                cnt = over - prev_overruns;
+                cnt += over - prev_overruns;
         prev_overruns = over;
         return cnt;
 }
@@ -310,8 +312,10 @@ static void __trace_mmiotrace_rw(struct trace_array *tr,
 
         event   = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
                                            &irq_flags);
-        if (!event)
+        if (!event) {
+                atomic_inc(&dropped_count);
                 return;
+        }
         entry   = ring_buffer_event_data(event);
         tracing_generic_entry_update(&entry->ent, 0, preempt_count());
         entry->ent.type                 = TRACE_MMIO_RW;
@@ -338,8 +342,10 @@ static void __trace_mmiotrace_map(struct trace_array *tr,
 
         event   = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
                                            &irq_flags);
-        if (!event)
+        if (!event) {
+                atomic_inc(&dropped_count);
                 return;
+        }
         entry   = ring_buffer_event_data(event);
         tracing_generic_entry_update(&entry->ent, 0, preempt_count());
         entry->ent.type                 = TRACE_MMIO_MAP;
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 88c8eb70f54a..bc8e80a86bca 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -23,10 +23,20 @@ static int trace_test_buffer_cpu(struct trace_array *tr, int cpu)
 {
         struct ring_buffer_event *event;
         struct trace_entry *entry;
+        unsigned int loops = 0;
 
         while ((event = ring_buffer_consume(tr->buffer, cpu, NULL))) {
                 entry = ring_buffer_event_data(event);
 
+                /*
+                 * The ring buffer is a size of trace_buf_size, if
+                 * we loop more than the size, there's something wrong
+                 * with the ring buffer.
+                 */
+                if (loops++ > trace_buf_size) {
+                        printk(KERN_CONT ".. bad ring buffer ");
+                        goto failed;
+                }
                 if (!trace_valid_entry(entry)) {
                         printk(KERN_CONT ".. invalid entry %d ",
                                 entry->type);
@@ -57,11 +67,20 @@ static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
 
         cnt = ring_buffer_entries(tr->buffer);
 
+        /*
+         * The trace_test_buffer_cpu runs a while loop to consume all data.
+         * If the calling tracer is broken, and is constantly filling
+         * the buffer, this will run forever, and hard lock the box.
+         * We disable the ring buffer while we do this test to prevent
+         * a hard lock up.
+         */
+        tracing_off();
         for_each_possible_cpu(cpu) {
                 ret = trace_test_buffer_cpu(tr, cpu);
                 if (ret)
                         break;
         }
+        tracing_on();
         __raw_spin_unlock(&ftrace_max_lock);
         local_irq_restore(flags);