Merge branch 'tip/perf/core' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/core

Pull tracing updated from Steve Rostedt.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

16 files changed, 288 insertions, 243 deletions

diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 6f51fed45f2d..53d6a3c51d87 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -1842,6 +1842,89 @@ an error.
  # cat buffer_size_kb
 85
 
+Snapshot
+--------
+CONFIG_TRACER_SNAPSHOT makes a generic snapshot feature
+available to all non latency tracers. (Latency tracers which
+record max latency, such as "irqsoff" or "wakeup", can't use
+this feature, since those are already using the snapshot
+mechanism internally.)
+
+Snapshot preserves a current trace buffer at a particular point
+in time without stopping tracing. Ftrace swaps the current
+buffer with a spare buffer, and tracing continues in the new
+current (=previous spare) buffer.
+
+The following debugfs files in "tracing" are related to this
+feature:
+
+  snapshot:
+
+        This is used to take a snapshot and to read the output
+        of the snapshot. Echo 1 into this file to allocate a
+        spare buffer and to take a snapshot (swap), then read
+        the snapshot from this file in the same format as
+        "trace" (described above in the section "The File
+        System"). Both reads snapshot and tracing are executable
+        in parallel. When the spare buffer is allocated, echoing
+        0 frees it, and echoing else (positive) values clear the
+        snapshot contents.
+        More details are shown in the table below.
+
+        status\input  |     0      |     1      |    else    |
+        --------------+------------+------------+------------+
+        not allocated |(do nothing)| alloc+swap |   EINVAL   |
+        --------------+------------+------------+------------+
+        allocated     |    free    |    swap    |   clear    |
+        --------------+------------+------------+------------+
+
+Here is an example of using the snapshot feature.
+
+ # echo 1 > events/sched/enable
+ # echo 1 > snapshot
+ # cat snapshot
+# tracer: nop
+#
+# entries-in-buffer/entries-written: 71/71   #P:8
+#
+#                              _-----=> irqs-off
+#                             / _----=> need-resched
+#                            | / _---=> hardirq/softirq
+#                            || / _--=> preempt-depth
+#                            ||| /     delay
+#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
+#              | |       |   ||||       |         |
+          <idle>-0     [005] d...  2440.603828: sched_switch: prev_comm=swapper/5 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=snapshot-test-2 next_pid=2242 next_prio=120
+           sleep-2242  [005] d...  2440.603846: sched_switch: prev_comm=snapshot-test-2 prev_pid=2242 prev_prio=120 prev_state=R ==> next_comm=kworker/5:1 next_pid=60 next_prio=120
+[...]
+          <idle>-0     [002] d...  2440.707230: sched_switch: prev_comm=swapper/2 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=snapshot-test-2 next_pid=2229 next_prio=120
+
+ # cat trace
+# tracer: nop
+#
+# entries-in-buffer/entries-written: 77/77   #P:8
+#
+#                              _-----=> irqs-off
+#                             / _----=> need-resched
+#                            | / _---=> hardirq/softirq
+#                            || / _--=> preempt-depth
+#                            ||| /     delay
+#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
+#              | |       |   ||||       |         |
+          <idle>-0     [007] d...  2440.707395: sched_switch: prev_comm=swapper/7 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=snapshot-test-2 next_pid=2243 next_prio=120
+ snapshot-test-2-2229  [002] d...  2440.707438: sched_switch: prev_comm=snapshot-test-2 prev_pid=2229 prev_prio=120 prev_state=S ==> next_comm=swapper/2 next_pid=0 next_prio=120
+[...]
+
+
+If you try to use this snapshot feature when current tracer is
+one of the latency tracers, you will get the following results.
+
+ # echo wakeup > current_tracer
+ # echo 1 > snapshot
+bash: echo: write error: Device or resource busy
+ # cat snapshot
+cat: snapshot: Device or resource busy
+
 -----------
 
 More details can be found in the source code, in the
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 6f8d0b77006b..13a54d0bdfa8 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -83,6 +83,9 @@ struct trace_iterator {
         long                    idx;
 
         cpumask_var_t           started;
+
+        /* it's true when current open file is snapshot */
+        bool                    snapshot;
 };
 
 enum trace_iter_flags {
diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index 519777e3fa01..1342e69542f3 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -167,6 +167,7 @@ unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
 unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
+unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);
 
 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index cdc9d284d24e..36567564e221 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -253,6 +253,16 @@ config FTRACE_SYSCALLS
         help
           Basic tracer to catch the syscall entry and exit events.
 
+config TRACER_SNAPSHOT
+        bool "Create a snapshot trace buffer"
+        select TRACER_MAX_TRACE
+        help
+          Allow tracing users to take snapshot of the current buffer using the
+          ftrace interface, e.g.:
+
+              echo 1 > /sys/kernel/debug/tracing/snapshot
+              cat snapshot
+
 config TRACE_BRANCH_PROFILING
         bool
         select GENERIC_TRACER
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 13950d9027cb..7244acde77b0 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3103,6 +3103,24 @@ ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu)
 EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu);
 
 /**
+ * ring_buffer_read_events_cpu - get the number of events successfully read
+ * @buffer: The ring buffer
+ * @cpu: The per CPU buffer to get the number of events read
+ */
+unsigned long
+ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu)
+{
+        struct ring_buffer_per_cpu *cpu_buffer;
+
+        if (!cpumask_test_cpu(cpu, buffer->cpumask))
+                return 0;
+
+        cpu_buffer = buffer->buffers[cpu];
+        return cpu_buffer->read;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_read_events_cpu);
+
+/**
  * ring_buffer_entries - get the number of entries in a buffer
  * @buffer: The ring buffer
  *
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d2a658349ca1..5d520b7bb4c5 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -249,7 +249,7 @@ static unsigned long		trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
 static struct tracer            *trace_types __read_mostly;
 
 /* current_trace points to the tracer that is currently active */
-static struct tracer            *current_trace __read_mostly;
+static struct tracer            *current_trace __read_mostly = &nop_trace;
 
 /*
  * trace_types_lock is used to protect the trace_types list.
@@ -710,12 +710,11 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 
         WARN_ON_ONCE(!irqs_disabled());
 
-        /* If we disabled the tracer, stop now */
-        if (current_trace == &nop_trace)
-                return;
-
-        if (WARN_ON_ONCE(!current_trace->use_max_tr))
+        if (!current_trace->allocated_snapshot) {
+                /* Only the nop tracer should hit this when disabling */
+                WARN_ON_ONCE(current_trace != &nop_trace);
                 return;
+        }
 
         arch_spin_lock(&ftrace_max_lock);
 
@@ -743,10 +742,8 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
                 return;
 
         WARN_ON_ONCE(!irqs_disabled());
-        if (!current_trace->use_max_tr) {
-                WARN_ON_ONCE(1);
+        if (WARN_ON_ONCE(!current_trace->allocated_snapshot))
                 return;
-        }
 
         arch_spin_lock(&ftrace_max_lock);
 
@@ -866,10 +863,13 @@ int register_tracer(struct tracer *type)
 
                 current_trace = type;
 
-                /* If we expanded the buffers, make sure the max is expanded too */
-                if (ring_buffer_expanded && type->use_max_tr)
-                        ring_buffer_resize(max_tr.buffer, trace_buf_size,
-                                                RING_BUFFER_ALL_CPUS);
+                if (type->use_max_tr) {
+                        /* If we expanded the buffers, make sure the max is expanded too */
+                        if (ring_buffer_expanded)
+                                ring_buffer_resize(max_tr.buffer, trace_buf_size,
+                                                   RING_BUFFER_ALL_CPUS);
+                        type->allocated_snapshot = true;
+                }
 
                 /* the test is responsible for initializing and enabling */
                 pr_info("Testing tracer %s: ", type->name);
@@ -885,10 +885,14 @@ int register_tracer(struct tracer *type)
                 /* Only reset on passing, to avoid touching corrupted buffers */
                 tracing_reset_online_cpus(tr);
 
-                /* Shrink the max buffer again */
-                if (ring_buffer_expanded && type->use_max_tr)
-                        ring_buffer_resize(max_tr.buffer, 1,
-                                                RING_BUFFER_ALL_CPUS);
+                if (type->use_max_tr) {
+                        type->allocated_snapshot = false;
+
+                        /* Shrink the max buffer again */
+                        if (ring_buffer_expanded)
+                                ring_buffer_resize(max_tr.buffer, 1,
+                                                   RING_BUFFER_ALL_CPUS);
+                }
 
                 printk(KERN_CONT "PASSED\n");
         }
@@ -1344,7 +1348,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
          */
         preempt_disable_notrace();
 
-        use_stack = ++__get_cpu_var(ftrace_stack_reserve);
+        use_stack = __this_cpu_inc_return(ftrace_stack_reserve);
         /*
          * We don't need any atomic variables, just a barrier.
          * If an interrupt comes in, we don't care, because it would
@@ -1398,7 +1402,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
  out:
         /* Again, don't let gcc optimize things here */
         barrier();
-        __get_cpu_var(ftrace_stack_reserve)--;
+        __this_cpu_dec(ftrace_stack_reserve);
         preempt_enable_notrace();
 
 }
@@ -1948,21 +1952,27 @@ void tracing_iter_reset(struct trace_iterator *iter, int cpu)
 static void *s_start(struct seq_file *m, loff_t *pos)
 {
         struct trace_iterator *iter = m->private;
-        static struct tracer *old_tracer;
         int cpu_file = iter->cpu_file;
         void *p = NULL;
         loff_t l = 0;
         int cpu;
 
-        /* copy the tracer to avoid using a global lock all around */
+        /*
+         * copy the tracer to avoid using a global lock all around.
+         * iter->trace is a copy of current_trace, the pointer to the
+         * name may be used instead of a strcmp(), as iter->trace->name
+         * will point to the same string as current_trace->name.
+         */
         mutex_lock(&trace_types_lock);
-        if (unlikely(old_tracer != current_trace && current_trace)) {
-                old_tracer = current_trace;
+        if (unlikely(current_trace && iter->trace->name != current_trace->name))
                 *iter->trace = *current_trace;
-        }
         mutex_unlock(&trace_types_lock);
 
-        atomic_inc(&trace_record_cmdline_disabled);
+        if (iter->snapshot && iter->trace->use_max_tr)
+                return ERR_PTR(-EBUSY);
+
+        if (!iter->snapshot)
+                atomic_inc(&trace_record_cmdline_disabled);
 
         if (*pos != iter->pos) {
                 iter->ent = NULL;
@@ -2001,7 +2011,11 @@ static void s_stop(struct seq_file *m, void *p)
 {
         struct trace_iterator *iter = m->private;
 
-        atomic_dec(&trace_record_cmdline_disabled);
+        if (iter->snapshot && iter->trace->use_max_tr)
+                return;
+
+        if (!iter->snapshot)
+                atomic_dec(&trace_record_cmdline_disabled);
         trace_access_unlock(iter->cpu_file);
         trace_event_read_unlock();
 }
@@ -2086,8 +2100,7 @@ print_trace_header(struct seq_file *m, struct trace_iterator *iter)
         unsigned long total;
         const char *name = "preemption";
 
-        if (type)
-                name = type->name;
+        name = type->name;
 
         get_total_entries(tr, &total, &entries);
 
@@ -2436,7 +2449,7 @@ static const struct seq_operations tracer_seq_ops = {
 };
 
 static struct trace_iterator *
-__tracing_open(struct inode *inode, struct file *file)
+__tracing_open(struct inode *inode, struct file *file, bool snapshot)
 {
         long cpu_file = (long) inode->i_private;
         struct trace_iterator *iter;
@@ -2463,16 +2476,16 @@ __tracing_open(struct inode *inode, struct file *file)
         if (!iter->trace)
                 goto fail;
 
-        if (current_trace)
-                *iter->trace = *current_trace;
+        *iter->trace = *current_trace;
 
         if (!zalloc_cpumask_var(&iter->started, GFP_KERNEL))
                 goto fail;
 
-        if (current_trace && current_trace->print_max)
+        if (current_trace->print_max || snapshot)
                 iter->tr = &max_tr;
         else
                 iter->tr = &global_trace;
+        iter->snapshot = snapshot;
         iter->pos = -1;
         mutex_init(&iter->mutex);
         iter->cpu_file = cpu_file;
@@ -2489,8 +2502,9 @@ __tracing_open(struct inode *inode, struct file *file)
         if (trace_clocks[trace_clock_id].in_ns)
                 iter->iter_flags |= TRACE_FILE_TIME_IN_NS;
 
-        /* stop the trace while dumping */
-        tracing_stop();
+        /* stop the trace while dumping if we are not opening "snapshot" */
+        if (!iter->snapshot)
+                tracing_stop();
 
         if (iter->cpu_file == TRACE_PIPE_ALL_CPU) {
                 for_each_tracing_cpu(cpu) {
@@ -2553,8 +2567,9 @@ static int tracing_release(struct inode *inode, struct file *file)
         if (iter->trace && iter->trace->close)
                 iter->trace->close(iter);
 
-        /* reenable tracing if it was previously enabled */
-        tracing_start();
+        if (!iter->snapshot)
+                /* reenable tracing if it was previously enabled */
+                tracing_start();
         mutex_unlock(&trace_types_lock);
 
         mutex_destroy(&iter->mutex);
@@ -2582,7 +2597,7 @@ static int tracing_open(struct inode *inode, struct file *file)
         }
 
         if (file->f_mode & FMODE_READ) {
-                iter = __tracing_open(inode, file);
+                iter = __tracing_open(inode, file, false);
                 if (IS_ERR(iter))
                         ret = PTR_ERR(iter);
                 else if (trace_flags & TRACE_ITER_LATENCY_FMT)
@@ -3020,10 +3035,7 @@ tracing_set_trace_read(struct file *filp, char __user *ubuf,
         int r;
 
         mutex_lock(&trace_types_lock);
-        if (current_trace)
-                r = sprintf(buf, "%s\n", current_trace->name);
-        else
-                r = sprintf(buf, "\n");
+        r = sprintf(buf, "%s\n", current_trace->name);
         mutex_unlock(&trace_types_lock);
 
         return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
@@ -3214,10 +3226,10 @@ static int tracing_set_tracer(const char *buf)
                 goto out;
 
         trace_branch_disable();
-        if (current_trace && current_trace->reset)
+        if (current_trace->reset)
                 current_trace->reset(tr);
 
-        had_max_tr = current_trace && current_trace->use_max_tr;
+        had_max_tr = current_trace->allocated_snapshot;
         current_trace = &nop_trace;
 
         if (had_max_tr && !t->use_max_tr) {
@@ -3236,6 +3248,8 @@ static int tracing_set_tracer(const char *buf)
                  */
                 ring_buffer_resize(max_tr.buffer, 1, RING_BUFFER_ALL_CPUS);
                 set_buffer_entries(&max_tr, 1);
+                tracing_reset_online_cpus(&max_tr);
+                current_trace->allocated_snapshot = false;
         }
         destroy_trace_option_files(topts);
 
@@ -3246,6 +3260,7 @@ static int tracing_set_tracer(const char *buf)
                                                    RING_BUFFER_ALL_CPUS);
                 if (ret < 0)
                         goto out;
+                t->allocated_snapshot = true;
         }
 
         if (t->init) {
@@ -3353,8 +3368,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
                 ret = -ENOMEM;
                 goto fail;
         }
-        if (current_trace)
-                *iter->trace = *current_trace;
+        *iter->trace = *current_trace;
 
         if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
                 ret = -ENOMEM;
@@ -3494,7 +3508,6 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
                   size_t cnt, loff_t *ppos)
 {
         struct trace_iterator *iter = filp->private_data;
-        static struct tracer *old_tracer;
         ssize_t sret;
 
         /* return any leftover data */
@@ -3506,10 +3519,8 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
 
         /* copy the tracer to avoid using a global lock all around */
         mutex_lock(&trace_types_lock);
-        if (unlikely(old_tracer != current_trace && current_trace)) {
-                old_tracer = current_trace;
+        if (unlikely(iter->trace->name != current_trace->name))
                 *iter->trace = *current_trace;
-        }
         mutex_unlock(&trace_types_lock);
 
         /*
@@ -3665,7 +3676,6 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
                 .ops            = &tracing_pipe_buf_ops,
                 .spd_release    = tracing_spd_release_pipe,
         };
-        static struct tracer *old_tracer;
         ssize_t ret;
         size_t rem;
         unsigned int i;
@@ -3675,10 +3685,8 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 
         /* copy the tracer to avoid using a global lock all around */
         mutex_lock(&trace_types_lock);
-        if (unlikely(old_tracer != current_trace && current_trace)) {
-                old_tracer = current_trace;
+        if (unlikely(iter->trace->name != current_trace->name))
                 *iter->trace = *current_trace;
-        }
         mutex_unlock(&trace_types_lock);
 
         mutex_lock(&iter->mutex);
@@ -4070,6 +4078,87 @@ static int tracing_clock_open(struct inode *inode, struct file *file)
         return single_open(file, tracing_clock_show, NULL);
 }
 
+#ifdef CONFIG_TRACER_SNAPSHOT
+static int tracing_snapshot_open(struct inode *inode, struct file *file)
+{
+        struct trace_iterator *iter;
+        int ret = 0;
+
+        if (file->f_mode & FMODE_READ) {
+                iter = __tracing_open(inode, file, true);
+                if (IS_ERR(iter))
+                        ret = PTR_ERR(iter);
+        }
+        return ret;
+}
+
+static ssize_t
+tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
+                       loff_t *ppos)
+{
+        unsigned long val;
+        int ret;
+
+        ret = tracing_update_buffers();
+        if (ret < 0)
+                return ret;
+
+        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+        if (ret)
+                return ret;
+
+        mutex_lock(&trace_types_lock);
+
+        if (current_trace->use_max_tr) {
+                ret = -EBUSY;
+                goto out;
+        }
+
+        switch (val) {
+        case 0:
+                if (current_trace->allocated_snapshot) {
+                        /* free spare buffer */
+                        ring_buffer_resize(max_tr.buffer, 1,
+                                           RING_BUFFER_ALL_CPUS);
+                        set_buffer_entries(&max_tr, 1);
+                        tracing_reset_online_cpus(&max_tr);
+                        current_trace->allocated_snapshot = false;
+                }
+                break;
+        case 1:
+                if (!current_trace->allocated_snapshot) {
+                        /* allocate spare buffer */
+                        ret = resize_buffer_duplicate_size(&max_tr,
+                                        &global_trace, RING_BUFFER_ALL_CPUS);
+                        if (ret < 0)
+                                break;
+                        current_trace->allocated_snapshot = true;
+                }
+
+                local_irq_disable();
+                /* Now, we're going to swap */
+                update_max_tr(&global_trace, current, smp_processor_id());
+                local_irq_enable();
+                break;
+        default:
+                if (current_trace->allocated_snapshot)
+                        tracing_reset_online_cpus(&max_tr);
+                else
+                        ret = -EINVAL;
+                break;
+        }
+
+        if (ret >= 0) {
+                *ppos += cnt;
+                ret = cnt;
+        }
+out:
+        mutex_unlock(&trace_types_lock);
+        return ret;
+}
+#endif /* CONFIG_TRACER_SNAPSHOT */
+
+
 static const struct file_operations tracing_max_lat_fops = {
         .open           = tracing_open_generic,
         .read           = tracing_max_lat_read,
@@ -4126,6 +4215,16 @@ static const struct file_operations trace_clock_fops = {
         .write          = tracing_clock_write,
 };
 
+#ifdef CONFIG_TRACER_SNAPSHOT
+static const struct file_operations snapshot_fops = {
+        .open           = tracing_snapshot_open,
+        .read           = seq_read,
+        .write          = tracing_snapshot_write,
+        .llseek         = tracing_seek,
+        .release        = tracing_release,
+};
+#endif /* CONFIG_TRACER_SNAPSHOT */
+
 struct ftrace_buffer_info {
         struct trace_array      *tr;
         void                    *spare;
@@ -4430,6 +4529,9 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
         cnt = ring_buffer_dropped_events_cpu(tr->buffer, cpu);
         trace_seq_printf(s, "dropped events: %ld\n", cnt);
 
+        cnt = ring_buffer_read_events_cpu(tr->buffer, cpu);
+        trace_seq_printf(s, "read events: %ld\n", cnt);
+
         count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
 
         kfree(s);
@@ -4506,7 +4608,7 @@ struct dentry *tracing_init_dentry(void)
 
 static struct dentry *d_percpu;
 
-struct dentry *tracing_dentry_percpu(void)
+static struct dentry *tracing_dentry_percpu(void)
 {
         static int once;
         struct dentry *d_tracer;
@@ -4922,6 +5024,11 @@ static __init int tracer_init_debugfs(void)
                         &ftrace_update_tot_cnt, &tracing_dyn_info_fops);
 #endif
 
+#ifdef CONFIG_TRACER_SNAPSHOT
+        trace_create_file("snapshot", 0644, d_tracer,
+                          (void *) TRACE_PIPE_ALL_CPU, &snapshot_fops);
+#endif
+
         create_trace_options_dir();
 
         for_each_tracing_cpu(cpu)
@@ -5030,6 +5137,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
         if (disable_tracing)
                 ftrace_kill();
 
+        /* Simulate the iterator */
         trace_init_global_iter(&iter);
 
         for_each_tracing_cpu(cpu) {
@@ -5041,10 +5149,6 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
         /* don't look at user memory in panic mode */
         trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
 
-        /* Simulate the iterator */
-        iter.tr = &global_trace;
-        iter.trace = current_trace;
-
         switch (oops_dump_mode) {
         case DUMP_ALL:
                 iter.cpu_file = TRACE_PIPE_ALL_CPU;
@@ -5189,7 +5293,7 @@ __init static int tracer_alloc_buffers(void)
         init_irq_work(&trace_work_wakeup, trace_wake_up);
 
         register_tracer(&nop_trace);
-        current_trace = &nop_trace;
+
         /* All seems OK, enable tracing */
         tracing_disabled = 0;
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 04a2c7ab1735..57d7e5397d56 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -287,6 +287,7 @@ struct tracer {
         struct tracer_flags     *flags;
         bool                    print_max;
         bool                    use_max_tr;
+        bool                    allocated_snapshot;
 };
 
 
diff --git a/kernel/trace/trace_clock.c b/kernel/trace/trace_clock.c
index 22b638b28e48..24bf48eabfcc 100644
--- a/kernel/trace/trace_clock.c
+++ b/kernel/trace/trace_clock.c
@@ -84,7 +84,7 @@ u64 notrace trace_clock_global(void)
         local_irq_save(flags);
 
         this_cpu = raw_smp_processor_id();
-        now = cpu_clock(this_cpu);
+        now = sched_clock_cpu(this_cpu);
         /*
          * If in an NMI context then dont risk lockups and return the
          * cpu_clock() time:
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 7008d2e13cf2..39ada66389cc 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -191,10 +191,16 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
 
         ftrace_pop_return_trace(&trace, &ret, frame_pointer);
         trace.rettime = trace_clock_local();
-        ftrace_graph_return(&trace);
         barrier();
         current->curr_ret_stack--;
 
+        /*
+         * The trace should run after decrementing the ret counter
+         * in case an interrupt were to come in. We don't want to
+         * lose the interrupt if max_depth is set.
+         */
+        ftrace_graph_return(&trace);
+
         if (unlikely(!ret)) {
                 ftrace_graph_stop();
                 WARN_ON(1);
diff --git a/samples/Kconfig b/samples/Kconfig
index 7b6792a18c05..6181c2cc9ca0 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -5,12 +5,6 @@ menuconfig SAMPLES
 
 if SAMPLES
 
-config SAMPLE_TRACEPOINTS
-        tristate "Build tracepoints examples -- loadable modules only"
-        depends on TRACEPOINTS && m
-        help
-          This build tracepoints example modules.
-
 config SAMPLE_TRACE_EVENTS
         tristate "Build trace_events examples -- loadable modules only"
         depends on EVENT_TRACING && m
diff --git a/samples/Makefile b/samples/Makefile
index 5ef08bba96ce..1a60c62e2045 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,4 @@
 # Makefile for Linux samples code
 
-obj-$(CONFIG_SAMPLES)   += kobject/ kprobes/ tracepoints/ trace_events/ \
+obj-$(CONFIG_SAMPLES)   += kobject/ kprobes/ trace_events/ \
                            hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/
diff --git a/samples/tracepoints/Makefile b/samples/tracepoints/Makefile
deleted file mode 100644
index 36479ad9ae14..000000000000
--- a/samples/tracepoints/Makefile
+++ /dev/null
@@ -1,6 +0,0 @@
-# builds the tracepoint example kernel modules;
-# then to use one (as root):  insmod <module_name.ko>
-
-obj-$(CONFIG_SAMPLE_TRACEPOINTS) += tracepoint-sample.o
-obj-$(CONFIG_SAMPLE_TRACEPOINTS) += tracepoint-probe-sample.o
-obj-$(CONFIG_SAMPLE_TRACEPOINTS) += tracepoint-probe-sample2.o
diff --git a/samples/tracepoints/tp-samples-trace.h b/samples/tracepoints/tp-samples-trace.h
deleted file mode 100644
index 4d46be965961..000000000000
--- a/samples/tracepoints/tp-samples-trace.h
+++ /dev/null
@@ -1,11 +0,0 @@
-#ifndef _TP_SAMPLES_TRACE_H
-#define _TP_SAMPLES_TRACE_H
-
-#include <linux/proc_fs.h>      /* for struct inode and struct file */
-#include <linux/tracepoint.h>
-
-DECLARE_TRACE(subsys_event,
-        TP_PROTO(struct inode *inode, struct file *file),
-        TP_ARGS(inode, file));
-DECLARE_TRACE_NOARGS(subsys_eventb);
-#endif
diff --git a/samples/tracepoints/tracepoint-probe-sample.c b/samples/tracepoints/tracepoint-probe-sample.c
deleted file mode 100644
index 744c0b9652a7..000000000000
--- a/samples/tracepoints/tracepoint-probe-sample.c
+++ /dev/null
@@ -1,57 +0,0 @@
-/*
- * tracepoint-probe-sample.c
- *
- * sample tracepoint probes.
- */
-
-#include <linux/module.h>
-#include <linux/file.h>
-#include <linux/dcache.h>
-#include "tp-samples-trace.h"
-
-/*
- * Here the caller only guarantees locking for struct file and struct inode.
- * Locking must therefore be done in the probe to use the dentry.
- */
-static void probe_subsys_event(void *ignore,
-                               struct inode *inode, struct file *file)
-{
-        path_get(&file->f_path);
-        dget(file->f_path.dentry);
-        printk(KERN_INFO "Event is encountered with filename %s\n",
-                file->f_path.dentry->d_name.name);
-        dput(file->f_path.dentry);
-        path_put(&file->f_path);
-}
-
-static void probe_subsys_eventb(void *ignore)
-{
-        printk(KERN_INFO "Event B is encountered\n");
-}
-
-static int __init tp_sample_trace_init(void)
-{
-        int ret;
-
-        ret = register_trace_subsys_event(probe_subsys_event, NULL);
-        WARN_ON(ret);
-        ret = register_trace_subsys_eventb(probe_subsys_eventb, NULL);
-        WARN_ON(ret);
-
-        return 0;
-}
-
-module_init(tp_sample_trace_init);
-
-static void __exit tp_sample_trace_exit(void)
-{
-        unregister_trace_subsys_eventb(probe_subsys_eventb, NULL);
-        unregister_trace_subsys_event(probe_subsys_event, NULL);
-        tracepoint_synchronize_unregister();
-}
-
-module_exit(tp_sample_trace_exit);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Mathieu Desnoyers");
-MODULE_DESCRIPTION("Tracepoint Probes Samples");
diff --git a/samples/tracepoints/tracepoint-probe-sample2.c b/samples/tracepoints/tracepoint-probe-sample2.c
deleted file mode 100644
index 9fcf990e5d4b..000000000000
--- a/samples/tracepoints/tracepoint-probe-sample2.c
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * tracepoint-probe-sample2.c
- *
- * 2nd sample tracepoint probes.
- */
-
-#include <linux/module.h>
-#include <linux/fs.h>
-#include "tp-samples-trace.h"
-
-/*
- * Here the caller only guarantees locking for struct file and struct inode.
- * Locking must therefore be done in the probe to use the dentry.
- */
-static void probe_subsys_event(void *ignore,
-                               struct inode *inode, struct file *file)
-{
-        printk(KERN_INFO "Event is encountered with inode number %lu\n",
-                inode->i_ino);
-}
-
-static int __init tp_sample_trace_init(void)
-{
-        int ret;
-
-        ret = register_trace_subsys_event(probe_subsys_event, NULL);
-        WARN_ON(ret);
-
-        return 0;
-}
-
-module_init(tp_sample_trace_init);
-
-static void __exit tp_sample_trace_exit(void)
-{
-        unregister_trace_subsys_event(probe_subsys_event, NULL);
-        tracepoint_synchronize_unregister();
-}
-
-module_exit(tp_sample_trace_exit);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Mathieu Desnoyers");
-MODULE_DESCRIPTION("Tracepoint Probes Samples");
diff --git a/samples/tracepoints/tracepoint-sample.c b/samples/tracepoints/tracepoint-sample.c
deleted file mode 100644
index f4d89e008c32..000000000000
--- a/samples/tracepoints/tracepoint-sample.c
+++ /dev/null
@@ -1,57 +0,0 @@
-/* tracepoint-sample.c
- *
- * Executes a tracepoint when /proc/tracepoint-sample is opened.
- *
- * (C) Copyright 2007 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
- *
- * This file is released under the GPLv2.
- * See the file COPYING for more details.
- */
-
-#include <linux/module.h>
-#include <linux/sched.h>
-#include <linux/proc_fs.h>
-#include "tp-samples-trace.h"
-
-DEFINE_TRACE(subsys_event);
-DEFINE_TRACE(subsys_eventb);
-
-struct proc_dir_entry *pentry_sample;
-
-static int my_open(struct inode *inode, struct file *file)
-{
-        int i;
-
-        trace_subsys_event(inode, file);
-        for (i = 0; i < 10; i++)
-                trace_subsys_eventb();
-        return -EPERM;
-}
-
-static const struct file_operations mark_ops = {
-        .open = my_open,
-        .llseek = noop_llseek,
-};
-
-static int __init sample_init(void)
-{
-        printk(KERN_ALERT "sample init\n");
-        pentry_sample = proc_create("tracepoint-sample", 0444, NULL,
-                &mark_ops);
-        if (!pentry_sample)
-                return -EPERM;
-        return 0;
-}
-
-static void __exit sample_exit(void)
-{
-        printk(KERN_ALERT "sample exit\n");
-        remove_proc_entry("tracepoint-sample", NULL);
-}
-
-module_init(sample_init)
-module_exit(sample_exit)
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Mathieu Desnoyers");
-MODULE_DESCRIPTION("Tracepoint sample");