1 files changed, 529 insertions, 164 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index bd38c5cfd8ad..960cbf44c844 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -4,21 +4,92 @@
  * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
  */
 #include <linux/ring_buffer.h>
+#include <linux/trace_clock.h>
+#include <linux/ftrace_irq.h>
 #include <linux/spinlock.h>
 #include <linux/debugfs.h>
 #include <linux/uaccess.h>
+#include <linux/hardirq.h>
 #include <linux/module.h>
 #include <linux/percpu.h>
 #include <linux/mutex.h>
-#include <linux/sched.h>        /* used for sched_clock() (for now) */
 #include <linux/init.h>
 #include <linux/hash.h>
 #include <linux/list.h>
+#include <linux/cpu.h>
 #include <linux/fs.h>
 
 #include "trace.h"
 
 /*
+ * The ring buffer is made up of a list of pages. A separate list of pages is
+ * allocated for each CPU. A writer may only write to a buffer that is
+ * associated with the CPU it is currently executing on.  A reader may read
+ * from any per cpu buffer.
+ *
+ * The reader is special. For each per cpu buffer, the reader has its own
+ * reader page. When a reader has read the entire reader page, this reader
+ * page is swapped with another page in the ring buffer.
+ *
+ * Now, as long as the writer is off the reader page, the reader can do what
+ * ever it wants with that page. The writer will never write to that page
+ * again (as long as it is out of the ring buffer).
+ *
+ * Here's some silly ASCII art.
+ *
+ *   +------+
+ *   |reader|          RING BUFFER
+ *   |page  |
+ *   +------+        +---+   +---+   +---+
+ *                   |   |-->|   |-->|   |
+ *                   +---+   +---+   +---+
+ *                     ^               |
+ *                     |               |
+ *                     +---------------+
+ *
+ *
+ *   +------+
+ *   |reader|          RING BUFFER
+ *   |page  |------------------v
+ *   +------+        +---+   +---+   +---+
+ *                   |   |-->|   |-->|   |
+ *                   +---+   +---+   +---+
+ *                     ^               |
+ *                     |               |
+ *                     +---------------+
+ *
+ *
+ *   +------+
+ *   |reader|          RING BUFFER
+ *   |page  |------------------v
+ *   +------+        +---+   +---+   +---+
+ *      ^            |   |-->|   |-->|   |
+ *      |            +---+   +---+   +---+
+ *      |                              |
+ *      |                              |
+ *      +------------------------------+
+ *
+ *
+ *   +------+
+ *   |buffer|          RING BUFFER
+ *   |page  |------------------v
+ *   +------+        +---+   +---+   +---+
+ *      ^            |   |   |   |-->|   |
+ *      |   New      +---+   +---+   +---+
+ *      |  Reader------^               |
+ *      |   page                       |
+ *      +------------------------------+
+ *
+ *
+ * After we make this swap, the reader can hand this page off to the splice
+ * code and be done with it. It can even allocate a new page if it needs to
+ * and swap that into the ring buffer.
+ *
+ * We will be using cmpxchg soon to make all this lockless.
+ *
+ */
+
+/*
  * A fast way to enable or disable all ring buffers is to
  * call tracing_on or tracing_off. Turning off the ring buffers
  * prevents all ring buffers from being recorded to.
@@ -57,7 +128,9 @@ enum {
         RB_BUFFERS_DISABLED     = 1 << RB_BUFFERS_DISABLED_BIT,
 };
 
-static long ring_buffer_flags __read_mostly = RB_BUFFERS_ON;
+static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON;
+
+#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data)
 
 /**
  * tracing_on - enable all tracing buffers
@@ -89,59 +162,92 @@ EXPORT_SYMBOL_GPL(tracing_off);
  * tracing_off_permanent - permanently disable ring buffers
  *
  * This function, once called, will disable all ring buffers
- * permanenty.
+ * permanently.
  */
 void tracing_off_permanent(void)
 {
         set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags);
 }
 
+/**
+ * tracing_is_on - show state of ring buffers enabled
+ */
+int tracing_is_on(void)
+{
+        return ring_buffer_flags == RB_BUFFERS_ON;
+}
+EXPORT_SYMBOL_GPL(tracing_is_on);
+
 #include "trace.h"
 
-/* Up this if you want to test the TIME_EXTENTS and normalization */
-#define DEBUG_SHIFT 0
+#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array))
+#define RB_ALIGNMENT            4U
+#define RB_MAX_SMALL_DATA       28
+
+enum {
+        RB_LEN_TIME_EXTEND = 8,
+        RB_LEN_TIME_STAMP = 16,
+};
 
-/* FIXME!!! */
-u64 ring_buffer_time_stamp(int cpu)
+static inline int rb_null_event(struct ring_buffer_event *event)
 {
-        u64 time;
+        return event->type == RINGBUF_TYPE_PADDING && event->time_delta == 0;
+}
 
-        preempt_disable_notrace();
-        /* shift to debug/test normalization and TIME_EXTENTS */
-        time = sched_clock() << DEBUG_SHIFT;
-        preempt_enable_no_resched_notrace();
+static inline int rb_discarded_event(struct ring_buffer_event *event)
+{
+        return event->type == RINGBUF_TYPE_PADDING && event->time_delta;
+}
 
-        return time;
+static void rb_event_set_padding(struct ring_buffer_event *event)
+{
+        event->type = RINGBUF_TYPE_PADDING;
+        event->time_delta = 0;
 }
-EXPORT_SYMBOL_GPL(ring_buffer_time_stamp);
 
-void ring_buffer_normalize_time_stamp(int cpu, u64 *ts)
+/**
+ * ring_buffer_event_discard - discard an event in the ring buffer
+ * @buffer: the ring buffer
+ * @event: the event to discard
+ *
+ * Sometimes a event that is in the ring buffer needs to be ignored.
+ * This function lets the user discard an event in the ring buffer
+ * and then that event will not be read later.
+ *
+ * Note, it is up to the user to be careful with this, and protect
+ * against races. If the user discards an event that has been consumed
+ * it is possible that it could corrupt the ring buffer.
+ */
+void ring_buffer_event_discard(struct ring_buffer_event *event)
 {
-        /* Just stupid testing the normalize function and deltas */
-        *ts >>= DEBUG_SHIFT;
+        event->type = RINGBUF_TYPE_PADDING;
+        /* time delta must be non zero */
+        if (!event->time_delta)
+                event->time_delta = 1;
 }
-EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp);
 
-#define RB_EVNT_HDR_SIZE (sizeof(struct ring_buffer_event))
-#define RB_ALIGNMENT_SHIFT      2
-#define RB_ALIGNMENT            (1 << RB_ALIGNMENT_SHIFT)
-#define RB_MAX_SMALL_DATA       28
+static unsigned
+rb_event_data_length(struct ring_buffer_event *event)
+{
+        unsigned length;
 
-enum {
-        RB_LEN_TIME_EXTEND = 8,
-        RB_LEN_TIME_STAMP = 16,
-};
+        if (event->len)
+                length = event->len * RB_ALIGNMENT;
+        else
+                length = event->array[0];
+        return length + RB_EVNT_HDR_SIZE;
+}
 
 /* inline for ring buffer fast paths */
-static inline unsigned
+static unsigned
 rb_event_length(struct ring_buffer_event *event)
 {
-        unsigned length;
-
         switch (event->type) {
         case RINGBUF_TYPE_PADDING:
-                /* undefined */
-                return -1;
+                if (rb_null_event(event))
+                        /* undefined */
+                        return -1;
+                return rb_event_data_length(event);
 
         case RINGBUF_TYPE_TIME_EXTEND:
                 return RB_LEN_TIME_EXTEND;
@@ -150,11 +256,7 @@ rb_event_length(struct ring_buffer_event *event)
                 return RB_LEN_TIME_STAMP;
 
         case RINGBUF_TYPE_DATA:
-                if (event->len)
-                        length = event->len << RB_ALIGNMENT_SHIFT;
-                else
-                        length = event->array[0];
-                return length + RB_EVNT_HDR_SIZE;
+                return rb_event_data_length(event);
         default:
                 BUG();
         }
@@ -179,7 +281,7 @@ unsigned ring_buffer_event_length(struct ring_buffer_event *event)
 EXPORT_SYMBOL_GPL(ring_buffer_event_length);
 
 /* inline for ring buffer fast paths */
-static inline void *
+static void *
 rb_event_data(struct ring_buffer_event *event)
 {
         BUG_ON(event->type != RINGBUF_TYPE_DATA);
@@ -209,7 +311,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data);
 
 struct buffer_data_page {
         u64              time_stamp;    /* page time stamp */
-        local_t          commit;        /* write commited index */
+        local_t          commit;        /* write committed index */
         unsigned char    data[];        /* data of buffer page */
 };
 
@@ -225,14 +327,25 @@ static void rb_init_page(struct buffer_data_page *bpage)
         local_set(&bpage->commit, 0);
 }
 
+/**
+ * ring_buffer_page_len - the size of data on the page.
+ * @page: The page to read
+ *
+ * Returns the amount of data on the page, including buffer page header.
+ */
+size_t ring_buffer_page_len(void *page)
+{
+        return local_read(&((struct buffer_data_page *)page)->commit)
+                + BUF_PAGE_HDR_SIZE;
+}
+
 /*
  * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing
  * this issue out.
  */
-static inline void free_buffer_page(struct buffer_page *bpage)
+static void free_buffer_page(struct buffer_page *bpage)
 {
-        if (bpage->page)
-                free_page((unsigned long)bpage->page);
+        free_page((unsigned long)bpage->page);
         kfree(bpage);
 }
 
@@ -246,7 +359,7 @@ static inline int test_time_stamp(u64 delta)
         return 0;
 }
 
-#define BUF_PAGE_SIZE (PAGE_SIZE - offsetof(struct buffer_data_page, data))
+#define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE)
 
 /*
  * head_page == tail_page && head == tail then buffer is empty.
@@ -260,7 +373,7 @@ struct ring_buffer_per_cpu {
         struct list_head                pages;
         struct buffer_page              *head_page;     /* read from head */
         struct buffer_page              *tail_page;     /* write to tail */
-        struct buffer_page              *commit_page;   /* commited pages */
+        struct buffer_page              *commit_page;   /* committed pages */
         struct buffer_page              *reader_page;
         unsigned long                   overrun;
         unsigned long                   entries;
@@ -273,12 +386,17 @@ struct ring_buffer {
         unsigned                        pages;
         unsigned                        flags;
         int                             cpus;
-        cpumask_var_t                   cpumask;
         atomic_t                        record_disabled;
+        cpumask_var_t                   cpumask;
 
         struct mutex                    mutex;
 
         struct ring_buffer_per_cpu      **buffers;
+
+#ifdef CONFIG_HOTPLUG_CPU
+        struct notifier_block           cpu_notify;
+#endif
+        u64                             (*clock)(void);
 };
 
 struct ring_buffer_iter {
@@ -299,11 +417,35 @@ struct ring_buffer_iter {
                 _____ret;                                       \
         })
 
+/* Up this if you want to test the TIME_EXTENTS and normalization */
+#define DEBUG_SHIFT 0
+
+u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu)
+{
+        u64 time;
+
+        preempt_disable_notrace();
+        /* shift to debug/test normalization and TIME_EXTENTS */
+        time = buffer->clock() << DEBUG_SHIFT;
+        preempt_enable_no_resched_notrace();
+
+        return time;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_time_stamp);
+
+void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
+                                      int cpu, u64 *ts)
+{
+        /* Just stupid testing the normalize function and deltas */
+        *ts >>= DEBUG_SHIFT;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp);
+
 /**
  * check_pages - integrity check of buffer pages
  * @cpu_buffer: CPU buffer with pages to test
  *
- * As a safty measure we check to make sure the data pages have not
+ * As a safety measure we check to make sure the data pages have not
  * been corrupted.
  */
 static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
@@ -421,7 +563,6 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
         struct list_head *head = &cpu_buffer->pages;
         struct buffer_page *bpage, *tmp;
 
-        list_del_init(&cpu_buffer->reader_page->list);
         free_buffer_page(cpu_buffer->reader_page);
 
         list_for_each_entry_safe(bpage, tmp, head, list) {
@@ -437,6 +578,11 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
  */
 extern int ring_buffer_page_too_big(void);
 
+#ifdef CONFIG_HOTPLUG_CPU
+static int rb_cpu_notify(struct notifier_block *self,
+                         unsigned long action, void *hcpu);
+#endif
+
 /**
  * ring_buffer_alloc - allocate a new ring_buffer
  * @size: the size in bytes per cpu that is needed.
@@ -469,12 +615,23 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags)
 
         buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
         buffer->flags = flags;
+        buffer->clock = trace_clock_local;
 
         /* need at least two pages */
         if (buffer->pages == 1)
                 buffer->pages++;
 
+        /*
+         * In case of non-hotplug cpu, if the ring-buffer is allocated
+         * in early initcall, it will not be notified of secondary cpus.
+         * In that off case, we need to allocate for all possible cpus.
+         */
+#ifdef CONFIG_HOTPLUG_CPU
+        get_online_cpus();
+        cpumask_copy(buffer->cpumask, cpu_online_mask);
+#else
         cpumask_copy(buffer->cpumask, cpu_possible_mask);
+#endif
         buffer->cpus = nr_cpu_ids;
 
         bsize = sizeof(void *) * nr_cpu_ids;
@@ -490,6 +647,13 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags)
                         goto fail_free_buffers;
         }
 
+#ifdef CONFIG_HOTPLUG_CPU
+        buffer->cpu_notify.notifier_call = rb_cpu_notify;
+        buffer->cpu_notify.priority = 0;
+        register_cpu_notifier(&buffer->cpu_notify);
+#endif
+
+        put_online_cpus();
         mutex_init(&buffer->mutex);
 
         return buffer;
@@ -503,6 +667,7 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags)
 
  fail_free_cpumask:
         free_cpumask_var(buffer->cpumask);
+        put_online_cpus();
 
  fail_free_buffer:
         kfree(buffer);
@@ -519,15 +684,29 @@ ring_buffer_free(struct ring_buffer *buffer)
 {
         int cpu;
 
+        get_online_cpus();
+
+#ifdef CONFIG_HOTPLUG_CPU
+        unregister_cpu_notifier(&buffer->cpu_notify);
+#endif
+
         for_each_buffer_cpu(buffer, cpu)
                 rb_free_cpu_buffer(buffer->buffers[cpu]);
 
+        put_online_cpus();
+
         free_cpumask_var(buffer->cpumask);
 
         kfree(buffer);
 }
 EXPORT_SYMBOL_GPL(ring_buffer_free);
 
+void ring_buffer_set_clock(struct ring_buffer *buffer,
+                           u64 (*clock)(void))
+{
+        buffer->clock = clock;
+}
+
 static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer);
 
 static void
@@ -627,16 +806,15 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
                 return size;
 
         mutex_lock(&buffer->mutex);
+        get_online_cpus();
 
         nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
 
         if (size < buffer_size) {
 
                 /* easy case, just free pages */
-                if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) {
-                        mutex_unlock(&buffer->mutex);
-                        return -1;
-                }
+                if (RB_WARN_ON(buffer, nr_pages >= buffer->pages))
+                        goto out_fail;
 
                 rm_pages = buffer->pages - nr_pages;
 
@@ -655,10 +833,8 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
          * add these pages to the cpu_buffers. Otherwise we just free
          * them all and return -ENOMEM;
          */
-        if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) {
-                mutex_unlock(&buffer->mutex);
-                return -1;
-        }
+        if (RB_WARN_ON(buffer, nr_pages <= buffer->pages))
+                goto out_fail;
 
         new_pages = nr_pages - buffer->pages;
 
@@ -683,13 +859,12 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
                 rb_insert_pages(cpu_buffer, &pages, new_pages);
         }
 
-        if (RB_WARN_ON(buffer, !list_empty(&pages))) {
-                mutex_unlock(&buffer->mutex);
-                return -1;
-        }
+        if (RB_WARN_ON(buffer, !list_empty(&pages)))
+                goto out_fail;
 
  out:
         buffer->pages = nr_pages;
+        put_online_cpus();
         mutex_unlock(&buffer->mutex);
 
         return size;
@@ -699,15 +874,20 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
                 list_del_init(&bpage->list);
                 free_buffer_page(bpage);
         }
+        put_online_cpus();
         mutex_unlock(&buffer->mutex);
         return -ENOMEM;
-}
-EXPORT_SYMBOL_GPL(ring_buffer_resize);
 
-static inline int rb_null_event(struct ring_buffer_event *event)
-{
-        return event->type == RINGBUF_TYPE_PADDING;
+        /*
+         * Something went totally wrong, and we are too paranoid
+         * to even clean up the mess.
+         */
+ out_fail:
+        put_online_cpus();
+        mutex_unlock(&buffer->mutex);
+        return -1;
 }
+EXPORT_SYMBOL_GPL(ring_buffer_resize);
 
 static inline void *
 __rb_data_page_index(struct buffer_data_page *bpage, unsigned index)
@@ -811,7 +991,7 @@ rb_event_index(struct ring_buffer_event *event)
         return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE);
 }
 
-static inline int
+static int
 rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer,
              struct ring_buffer_event *event)
 {
@@ -825,7 +1005,7 @@ rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer,
                 rb_commit_index(cpu_buffer) == index;
 }
 
-static inline void
+static void
 rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer,
                     struct ring_buffer_event *event)
 {
@@ -850,7 +1030,7 @@ rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer,
         local_set(&cpu_buffer->commit_page->page->commit, index);
 }
 
-static inline void
+static void
 rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer)
 {
         /*
@@ -896,7 +1076,7 @@ static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
         cpu_buffer->reader_page->read = 0;
 }
 
-static inline void rb_inc_iter(struct ring_buffer_iter *iter)
+static void rb_inc_iter(struct ring_buffer_iter *iter)
 {
         struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer;
 
@@ -926,7 +1106,7 @@ static inline void rb_inc_iter(struct ring_buffer_iter *iter)
  * and with this, we can determine what to place into the
  * data field.
  */
-static inline void
+static void
 rb_update_event(struct ring_buffer_event *event,
                          unsigned type, unsigned length)
 {
@@ -938,15 +1118,11 @@ rb_update_event(struct ring_buffer_event *event,
                 break;
 
         case RINGBUF_TYPE_TIME_EXTEND:
-                event->len =
-                        (RB_LEN_TIME_EXTEND + (RB_ALIGNMENT-1))
-                        >> RB_ALIGNMENT_SHIFT;
+                event->len = DIV_ROUND_UP(RB_LEN_TIME_EXTEND, RB_ALIGNMENT);
                 break;
 
         case RINGBUF_TYPE_TIME_STAMP:
-                event->len =
-                        (RB_LEN_TIME_STAMP + (RB_ALIGNMENT-1))
-                        >> RB_ALIGNMENT_SHIFT;
+                event->len = DIV_ROUND_UP(RB_LEN_TIME_STAMP, RB_ALIGNMENT);
                 break;
 
         case RINGBUF_TYPE_DATA:
@@ -955,16 +1131,14 @@ rb_update_event(struct ring_buffer_event *event,
                         event->len = 0;
                         event->array[0] = length;
                 } else
-                        event->len =
-                                (length + (RB_ALIGNMENT-1))
-                                >> RB_ALIGNMENT_SHIFT;
+                        event->len = DIV_ROUND_UP(length, RB_ALIGNMENT);
                 break;
         default:
                 BUG();
         }
 }
 
-static inline unsigned rb_calculate_event_length(unsigned length)
+static unsigned rb_calculate_event_length(unsigned length)
 {
         struct ring_buffer_event event; /* Used only for sizeof array */
 
@@ -990,6 +1164,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
         struct ring_buffer *buffer = cpu_buffer->buffer;
         struct ring_buffer_event *event;
         unsigned long flags;
+        bool lock_taken = false;
 
         commit_page = cpu_buffer->commit_page;
         /* we just need to protect against interrupts */
@@ -1003,7 +1178,30 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
                 struct buffer_page *next_page = tail_page;
 
                 local_irq_save(flags);
-                __raw_spin_lock(&cpu_buffer->lock);
+                /*
+                 * Since the write to the buffer is still not
+                 * fully lockless, we must be careful with NMIs.
+                 * The locks in the writers are taken when a write
+                 * crosses to a new page. The locks protect against
+                 * races with the readers (this will soon be fixed
+                 * with a lockless solution).
+                 *
+                 * Because we can not protect against NMIs, and we
+                 * want to keep traces reentrant, we need to manage
+                 * what happens when we are in an NMI.
+                 *
+                 * NMIs can happen after we take the lock.
+                 * If we are in an NMI, only take the lock
+                 * if it is not already taken. Otherwise
+                 * simply fail.
+                 */
+                if (unlikely(in_nmi())) {
+                        if (!__raw_spin_trylock(&cpu_buffer->lock))
+                                goto out_reset;
+                } else
+                        __raw_spin_lock(&cpu_buffer->lock);
+
+                lock_taken = true;
 
                 rb_inc_page(cpu_buffer, &next_page);
 
@@ -1012,7 +1210,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 
                 /* we grabbed the lock before incrementing */
                 if (RB_WARN_ON(cpu_buffer, next_page == reader_page))
-                        goto out_unlock;
+                        goto out_reset;
 
                 /*
                  * If for some reason, we had an interrupt storm that made
@@ -1021,12 +1219,12 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
                  */
                 if (unlikely(next_page == commit_page)) {
                         WARN_ON_ONCE(1);
-                        goto out_unlock;
+                        goto out_reset;
                 }
 
                 if (next_page == head_page) {
                         if (!(buffer->flags & RB_FL_OVERWRITE))
-                                goto out_unlock;
+                                goto out_reset;
 
                         /* tail_page has not moved yet? */
                         if (tail_page == cpu_buffer->tail_page) {
@@ -1050,7 +1248,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
                         cpu_buffer->tail_page = next_page;
 
                         /* reread the time stamp */
-                        *ts = ring_buffer_time_stamp(cpu_buffer->cpu);
+                        *ts = ring_buffer_time_stamp(buffer, cpu_buffer->cpu);
                         cpu_buffer->tail_page->page->time_stamp = *ts;
                 }
 
@@ -1060,7 +1258,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
                 if (tail < BUF_PAGE_SIZE) {
                         /* Mark the rest of the page with padding */
                         event = __rb_page_index(tail_page, tail);
-                        event->type = RINGBUF_TYPE_PADDING;
+                        rb_event_set_padding(event);
                 }
 
                 if (tail <= BUF_PAGE_SIZE)
@@ -1100,12 +1298,13 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 
         return event;
 
- out_unlock:
+ out_reset:
         /* reset write */
         if (tail <= BUF_PAGE_SIZE)
                 local_set(&tail_page->write, tail);
 
-        __raw_spin_unlock(&cpu_buffer->lock);
+        if (likely(lock_taken))
+                __raw_spin_unlock(&cpu_buffer->lock);
         local_irq_restore(flags);
         return NULL;
 }
@@ -1192,7 +1391,7 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
         if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000))
                 return NULL;
 
-        ts = ring_buffer_time_stamp(cpu_buffer->cpu);
+        ts = ring_buffer_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu);
 
         /*
          * Only the first commit can update the timestamp.
@@ -1265,7 +1464,6 @@ static DEFINE_PER_CPU(int, rb_need_resched);
  * ring_buffer_lock_reserve - reserve a part of the buffer
  * @buffer: the ring buffer to reserve from
  * @length: the length of the data to reserve (excluding event header)
- * @flags: a pointer to save the interrupt flags
  *
  * Returns a reseverd event on the ring buffer to copy directly to.
  * The user of this interface will need to get the body to write into
@@ -1278,9 +1476,7 @@ static DEFINE_PER_CPU(int, rb_need_resched);
  * If NULL is returned, then nothing has been allocated or locked.
  */
 struct ring_buffer_event *
-ring_buffer_lock_reserve(struct ring_buffer *buffer,
-                         unsigned long length,
-                         unsigned long *flags)
+ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length)
 {
         struct ring_buffer_per_cpu *cpu_buffer;
         struct ring_buffer_event *event;
@@ -1347,15 +1543,13 @@ static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer,
  * ring_buffer_unlock_commit - commit a reserved
  * @buffer: The buffer to commit to
  * @event: The event pointer to commit.
- * @flags: the interrupt flags received from ring_buffer_lock_reserve.
  *
  * This commits the data to the ring buffer, and releases any locks held.
  *
  * Must be paired with ring_buffer_lock_reserve.
  */
 int ring_buffer_unlock_commit(struct ring_buffer *buffer,
-                              struct ring_buffer_event *event,
-                              unsigned long flags)
+                              struct ring_buffer_event *event)
 {
         struct ring_buffer_per_cpu *cpu_buffer;
         int cpu = raw_smp_processor_id();
@@ -1438,7 +1632,7 @@ int ring_buffer_write(struct ring_buffer *buffer,
 }
 EXPORT_SYMBOL_GPL(ring_buffer_write);
 
-static inline int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer)
+static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer)
 {
         struct buffer_page *reader = cpu_buffer->reader_page;
         struct buffer_page *head = cpu_buffer->head_page;
@@ -1528,12 +1722,15 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu);
 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu)
 {
         struct ring_buffer_per_cpu *cpu_buffer;
+        unsigned long ret;
 
         if (!cpumask_test_cpu(cpu, buffer->cpumask))
                 return 0;
 
         cpu_buffer = buffer->buffers[cpu];
-        return cpu_buffer->entries;
+        ret = cpu_buffer->entries;
+
+        return ret;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu);
 
@@ -1545,12 +1742,15 @@ EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu);
 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu)
 {
         struct ring_buffer_per_cpu *cpu_buffer;
+        unsigned long ret;
 
         if (!cpumask_test_cpu(cpu, buffer->cpumask))
                 return 0;
 
         cpu_buffer = buffer->buffers[cpu];
-        return cpu_buffer->overrun;
+        ret = cpu_buffer->overrun;
+
+        return ret;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu);
 
@@ -1627,9 +1827,14 @@ static void rb_iter_reset(struct ring_buffer_iter *iter)
  */
 void ring_buffer_iter_reset(struct ring_buffer_iter *iter)
 {
-        struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer;
+        struct ring_buffer_per_cpu *cpu_buffer;
         unsigned long flags;
 
+        if (!iter)
+                return;
+
+        cpu_buffer = iter->cpu_buffer;
+
         spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
         rb_iter_reset(iter);
         spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
@@ -1803,7 +2008,7 @@ static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer)
 
         event = rb_reader_event(cpu_buffer);
 
-        if (event->type == RINGBUF_TYPE_DATA)
+        if (event->type == RINGBUF_TYPE_DATA || rb_discarded_event(event))
                 cpu_buffer->entries--;
 
         rb_update_read_stamp(cpu_buffer, event);
@@ -1864,9 +2069,6 @@ rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
         struct buffer_page *reader;
         int nr_loops = 0;
 
-        if (!cpumask_test_cpu(cpu, buffer->cpumask))
-                return NULL;
-
         cpu_buffer = buffer->buffers[cpu];
 
  again:
@@ -1889,9 +2091,18 @@ rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
 
         switch (event->type) {
         case RINGBUF_TYPE_PADDING:
-                RB_WARN_ON(cpu_buffer, 1);
+                if (rb_null_event(event))
+                        RB_WARN_ON(cpu_buffer, 1);
+                /*
+                 * Because the writer could be discarding every
+                 * event it creates (which would probably be bad)
+                 * if we were to go back to "again" then we may never
+                 * catch up, and will trigger the warn on, or lock
+                 * the box. Return the padding, and we will release
+                 * the current locks, and try again.
+                 */
                 rb_advance_reader(cpu_buffer);
-                return NULL;
+                return event;
 
         case RINGBUF_TYPE_TIME_EXTEND:
                 /* Internal data, OK to advance */
@@ -1906,7 +2117,8 @@ rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
         case RINGBUF_TYPE_DATA:
                 if (ts) {
                         *ts = cpu_buffer->read_stamp + event->time_delta;
-                        ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts);
+                        ring_buffer_normalize_time_stamp(buffer,
+                                                         cpu_buffer->cpu, ts);
                 }
                 return event;
 
@@ -1951,8 +2163,12 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
 
         switch (event->type) {
         case RINGBUF_TYPE_PADDING:
-                rb_inc_iter(iter);
-                goto again;
+                if (rb_null_event(event)) {
+                        rb_inc_iter(iter);
+                        goto again;
+                }
+                rb_advance_iter(iter);
+                return event;
 
         case RINGBUF_TYPE_TIME_EXTEND:
                 /* Internal data, OK to advance */
@@ -1967,7 +2183,8 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
         case RINGBUF_TYPE_DATA:
                 if (ts) {
                         *ts = iter->read_stamp + event->time_delta;
-                        ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts);
+                        ring_buffer_normalize_time_stamp(buffer,
+                                                         cpu_buffer->cpu, ts);
                 }
                 return event;
 
@@ -1995,10 +2212,19 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
         struct ring_buffer_event *event;
         unsigned long flags;
 
+        if (!cpumask_test_cpu(cpu, buffer->cpumask))
+                return NULL;
+
+ again:
         spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
         event = rb_buffer_peek(buffer, cpu, ts);
         spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
 
+        if (event && event->type == RINGBUF_TYPE_PADDING) {
+                cpu_relax();
+                goto again;
+        }
+
         return event;
 }
 
@@ -2017,10 +2243,16 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
         struct ring_buffer_event *event;
         unsigned long flags;
 
+ again:
         spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
         event = rb_iter_peek(iter, ts);
         spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
 
+        if (event && event->type == RINGBUF_TYPE_PADDING) {
+                cpu_relax();
+                goto again;
+        }
+
         return event;
 }
 
@@ -2035,24 +2267,37 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
 struct ring_buffer_event *
 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts)
 {
-        struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
-        struct ring_buffer_event *event;
+        struct ring_buffer_per_cpu *cpu_buffer;
+        struct ring_buffer_event *event = NULL;
         unsigned long flags;
 
+ again:
+        /* might be called in atomic */
+        preempt_disable();
+
         if (!cpumask_test_cpu(cpu, buffer->cpumask))
-                return NULL;
+                goto out;
 
+        cpu_buffer = buffer->buffers[cpu];
         spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
 
         event = rb_buffer_peek(buffer, cpu, ts);
         if (!event)
-                goto out;
+                goto out_unlock;
 
         rb_advance_reader(cpu_buffer);
 
- out:
+ out_unlock:
         spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
 
+ out:
+        preempt_enable();
+
+        if (event && event->type == RINGBUF_TYPE_PADDING) {
+                cpu_relax();
+                goto again;
+        }
+
         return event;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_consume);
@@ -2131,6 +2376,7 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts)
         struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer;
         unsigned long flags;
 
+ again:
         spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
         event = rb_iter_peek(iter, ts);
         if (!event)
@@ -2140,6 +2386,11 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts)
  out:
         spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
 
+        if (event && event->type == RINGBUF_TYPE_PADDING) {
+                cpu_relax();
+                goto again;
+        }
+
         return event;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_read);
@@ -2232,6 +2483,7 @@ int ring_buffer_empty(struct ring_buffer *buffer)
                 if (!rb_per_cpu_empty(cpu_buffer))
                         return 0;
         }
+
         return 1;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_empty);
@@ -2244,12 +2496,16 @@ EXPORT_SYMBOL_GPL(ring_buffer_empty);
 int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu)
 {
         struct ring_buffer_per_cpu *cpu_buffer;
+        int ret;
 
         if (!cpumask_test_cpu(cpu, buffer->cpumask))
                 return 1;
 
         cpu_buffer = buffer->buffers[cpu];
-        return rb_per_cpu_empty(cpu_buffer);
+        ret = rb_per_cpu_empty(cpu_buffer);
+
+
+        return ret;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu);
 
@@ -2268,18 +2524,36 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 {
         struct ring_buffer_per_cpu *cpu_buffer_a;
         struct ring_buffer_per_cpu *cpu_buffer_b;
+        int ret = -EINVAL;
 
         if (!cpumask_test_cpu(cpu, buffer_a->cpumask) ||
             !cpumask_test_cpu(cpu, buffer_b->cpumask))
-                return -EINVAL;
+                goto out;
 
         /* At least make sure the two buffers are somewhat the same */
         if (buffer_a->pages != buffer_b->pages)
-                return -EINVAL;
+                goto out;
+
+        ret = -EAGAIN;
+
+        if (ring_buffer_flags != RB_BUFFERS_ON)
+                goto out;
+
+        if (atomic_read(&buffer_a->record_disabled))
+                goto out;
+
+        if (atomic_read(&buffer_b->record_disabled))
+                goto out;
 
         cpu_buffer_a = buffer_a->buffers[cpu];
         cpu_buffer_b = buffer_b->buffers[cpu];
 
+        if (atomic_read(&cpu_buffer_a->record_disabled))
+                goto out;
+
+        if (atomic_read(&cpu_buffer_b->record_disabled))
+                goto out;
+
         /*
          * We can't do a synchronize_sched here because this
          * function can be called in atomic context.
@@ -2298,18 +2572,21 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
         atomic_dec(&cpu_buffer_a->record_disabled);
         atomic_dec(&cpu_buffer_b->record_disabled);
 
-        return 0;
+        ret = 0;
+out:
+        return ret;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu);
 
 static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer,
-                              struct buffer_data_page *bpage)
+                              struct buffer_data_page *bpage,
+                              unsigned int offset)
 {
         struct ring_buffer_event *event;
         unsigned long head;
 
         __raw_spin_lock(&cpu_buffer->lock);
-        for (head = 0; head < local_read(&bpage->commit);
+        for (head = offset; head < local_read(&bpage->commit);
              head += rb_event_length(event)) {
 
                 event = __rb_data_page_index(bpage, head);
@@ -2340,8 +2617,8 @@ static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer,
  */
 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer)
 {
-        unsigned long addr;
         struct buffer_data_page *bpage;
+        unsigned long addr;
 
         addr = __get_free_page(GFP_KERNEL);
         if (!addr)
@@ -2349,6 +2626,8 @@ void *ring_buffer_alloc_read_page(struct ring_buffer *buffer)
 
         bpage = (void *)addr;
 
+        rb_init_page(bpage);
+
         return bpage;
 }
 
@@ -2368,6 +2647,7 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data)
  * ring_buffer_read_page - extract a page from the ring buffer
  * @buffer: buffer to extract from
  * @data_page: the page to use allocated from ring_buffer_alloc_read_page
+ * @len: amount to extract
  * @cpu: the cpu of the buffer to extract
  * @full: should the extraction only happen when the page is full.
  *
@@ -2377,12 +2657,12 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data)
  * to swap with a page in the ring buffer.
  *
  * for example:
- *      rpage = ring_buffer_alloc_page(buffer);
+ *      rpage = ring_buffer_alloc_read_page(buffer);
  *      if (!rpage)
  *              return error;
- *      ret = ring_buffer_read_page(buffer, &rpage, cpu, 0);
- *      if (ret)
- *              process_page(rpage);
+ *      ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0);
+ *      if (ret >= 0)
+ *              process_page(rpage, ret);
  *
  * When @full is set, the function will not return true unless
  * the writer is off the reader page.
@@ -2393,72 +2673,118 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data)
  *  responsible for that.
  *
  * Returns:
- *  1 if data has been transferred
- *  0 if no data has been transferred.
+ *  >=0 if data has been transferred, returns the offset of consumed data.
+ *  <0 if no data has been transferred.
  */
 int ring_buffer_read_page(struct ring_buffer *buffer,
-                            void **data_page, int cpu, int full)
+                          void **data_page, size_t len, int cpu, int full)
 {
         struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
         struct ring_buffer_event *event;
         struct buffer_data_page *bpage;
+        struct buffer_page *reader;
         unsigned long flags;
-        int ret = 0;
+        unsigned int commit;
+        unsigned int read;
+        u64 save_timestamp;
+        int ret = -1;
+
+        if (!cpumask_test_cpu(cpu, buffer->cpumask))
+                goto out;
+
+        /*
+         * If len is not big enough to hold the page header, then
+         * we can not copy anything.
+         */
+        if (len <= BUF_PAGE_HDR_SIZE)
+                goto out;
+
+        len -= BUF_PAGE_HDR_SIZE;
 
         if (!data_page)
-                return 0;
+                goto out;
 
         bpage = *data_page;
         if (!bpage)
-                return 0;
+                goto out;
 
         spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
 
-        /*
-         * rb_buffer_peek will get the next ring buffer if
-         * the current reader page is empty.
-         */
-        event = rb_buffer_peek(buffer, cpu, NULL);
-        if (!event)
-                goto out;
+        reader = rb_get_reader_page(cpu_buffer);
+        if (!reader)
+                goto out_unlock;
+
+        event = rb_reader_event(cpu_buffer);
+
+        read = reader->read;
+        commit = rb_page_commit(reader);
 
-        /* check for data */
-        if (!local_read(&cpu_buffer->reader_page->page->commit))
-                goto out;
         /*
-         * If the writer is already off of the read page, then simply
-         * switch the read page with the given page. Otherwise
-         * we need to copy the data from the reader to the writer.
+         * If this page has been partially read or
+         * if len is not big enough to read the rest of the page or
+         * a writer is still on the page, then
+         * we must copy the data from the page to the buffer.
+         * Otherwise, we can simply swap the page with the one passed in.
          */
-        if (cpu_buffer->reader_page == cpu_buffer->commit_page) {
-                unsigned int read = cpu_buffer->reader_page->read;
+        if (read || (len < (commit - read)) ||
+            cpu_buffer->reader_page == cpu_buffer->commit_page) {
+                struct buffer_data_page *rpage = cpu_buffer->reader_page->page;
+                unsigned int rpos = read;
+                unsigned int pos = 0;
+                unsigned int size;
 
                 if (full)
-                        goto out;
-                /* The writer is still on the reader page, we must copy */
-                bpage = cpu_buffer->reader_page->page;
-                memcpy(bpage->data,
-                       cpu_buffer->reader_page->page->data + read,
-                       local_read(&bpage->commit) - read);
+                        goto out_unlock;
+
+                if (len > (commit - read))
+                        len = (commit - read);
+
+                size = rb_event_length(event);
+
+                if (len < size)
+                        goto out_unlock;
 
-                /* consume what was read */
-                cpu_buffer->reader_page += read;
+                /* save the current timestamp, since the user will need it */
+                save_timestamp = cpu_buffer->read_stamp;
 
+                /* Need to copy one event at a time */
+                do {
+                        memcpy(bpage->data + pos, rpage->data + rpos, size);
+
+                        len -= size;
+
+                        rb_advance_reader(cpu_buffer);
+                        rpos = reader->read;
+                        pos += size;
+
+                        event = rb_reader_event(cpu_buffer);
+                        size = rb_event_length(event);
+                } while (len > size);
+
+                /* update bpage */
+                local_set(&bpage->commit, pos);
+                bpage->time_stamp = save_timestamp;
+
+                /* we copied everything to the beginning */
+                read = 0;
         } else {
                 /* swap the pages */
                 rb_init_page(bpage);
-                bpage = cpu_buffer->reader_page->page;
-                cpu_buffer->reader_page->page = *data_page;
-                cpu_buffer->reader_page->read = 0;
+                bpage = reader->page;
+                reader->page = *data_page;
+                local_set(&reader->write, 0);
+                reader->read = 0;
                 *data_page = bpage;
+
+                /* update the entry counter */
+                rb_remove_entries(cpu_buffer, bpage, read);
         }
-        ret = 1;
+        ret = read;
 
-        /* update the entry counter */
-        rb_remove_entries(cpu_buffer, bpage);
- out:
+ out_unlock:
         spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
 
+ out:
         return ret;
 }
 
@@ -2466,7 +2792,7 @@ static ssize_t
 rb_simple_read(struct file *filp, char __user *ubuf,
                size_t cnt, loff_t *ppos)
 {
-        long *p = filp->private_data;
+        unsigned long *p = filp->private_data;
         char buf[64];
         int r;
 
@@ -2482,9 +2808,9 @@ static ssize_t
 rb_simple_write(struct file *filp, const char __user *ubuf,
                 size_t cnt, loff_t *ppos)
 {
-        long *p = filp->private_data;
+        unsigned long *p = filp->private_data;
         char buf[64];
-        long val;
+        unsigned long val;
         int ret;
 
         if (cnt >= sizeof(buf))
@@ -2509,7 +2835,7 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
         return cnt;
 }
 
-static struct file_operations rb_simple_fops = {
+static const struct file_operations rb_simple_fops = {
         .open           = tracing_open_generic,
         .read           = rb_simple_read,
         .write          = rb_simple_write,
@@ -2532,3 +2858,42 @@ static __init int rb_init_debugfs(void)
 }
 
 fs_initcall(rb_init_debugfs);
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int rb_cpu_notify(struct notifier_block *self,
+                         unsigned long action, void *hcpu)
+{
+        struct ring_buffer *buffer =
+                container_of(self, struct ring_buffer, cpu_notify);
+        long cpu = (long)hcpu;
+
+        switch (action) {
+        case CPU_UP_PREPARE:
+        case CPU_UP_PREPARE_FROZEN:
+                if (cpu_isset(cpu, *buffer->cpumask))
+                        return NOTIFY_OK;
+
+                buffer->buffers[cpu] =
+                        rb_allocate_cpu_buffer(buffer, cpu);
+                if (!buffer->buffers[cpu]) {
+                        WARN(1, "failed to allocate ring buffer on CPU %ld\n",
+                             cpu);
+                        return NOTIFY_OK;
+                }
+                smp_wmb();
+                cpu_set(cpu, *buffer->cpumask);
+                break;
+        case CPU_DOWN_PREPARE:
+        case CPU_DOWN_PREPARE_FROZEN:
+                /*
+                 * Do nothing.
+                 *  If we were to free the buffer, then the user would
+                 *  lose any trace that was in the buffer.
+                 */
+                break;
+        default:
+                break;
+        }
+        return NOTIFY_OK;
+}
+#endif