5 files changed, 55 insertions, 44 deletions

diff --git a/Documentation/ftrace.txt b/Documentation/ftrace.txt
index 9cc4d685dde5..753f4de4b175 100644
--- a/Documentation/ftrace.txt
+++ b/Documentation/ftrace.txt
@@ -82,7 +82,7 @@ of ftrace. Here is a list of some of the key files:
                 tracer is not adding more data, they will display
                 the same information every time they are read.
 
-  iter_ctrl: This file lets the user control the amount of data
+  trace_options: This file lets the user control the amount of data
                 that is displayed in one of the above output
                 files.
 
@@ -94,10 +94,10 @@ of ftrace. Here is a list of some of the key files:
                 only be recorded if the latency is greater than
                 the value in this file. (in microseconds)
 
-  trace_entries: This sets or displays the number of bytes each CPU
+  buffer_size_kb: This sets or displays the number of kilobytes each CPU
                 buffer can hold. The tracer buffers are the same size
                 for each CPU. The displayed number is the size of the
-                 CPU buffer and not total size of all buffers. The
+                CPU buffer and not total size of all buffers. The
                 trace buffers are allocated in pages (blocks of memory
                 that the kernel uses for allocation, usually 4 KB in size).
                 If the last page allocated has room for more bytes
@@ -316,23 +316,23 @@ The above is mostly meaningful for kernel developers.
   The rest is the same as the 'trace' file.
 
 
-iter_ctrl
----------
+trace_options
+-------------
 
-The iter_ctrl file is used to control what gets printed in the trace
+The trace_options file is used to control what gets printed in the trace
 output. To see what is available, simply cat the file:
 
-  cat /debug/tracing/iter_ctrl
+  cat /debug/tracing/trace_options
   print-parent nosym-offset nosym-addr noverbose noraw nohex nobin \
  noblock nostacktrace nosched-tree
 
 To disable one of the options, echo in the option prepended with "no".
 
-  echo noprint-parent > /debug/tracing/iter_ctrl
+  echo noprint-parent > /debug/tracing/trace_options
 
 To enable an option, leave off the "no".
 
-  echo sym-offset > /debug/tracing/iter_ctrl
+  echo sym-offset > /debug/tracing/trace_options
 
 Here are the available options:
 
@@ -1299,41 +1299,29 @@ trace entries
 -------------
 
 Having too much or not enough data can be troublesome in diagnosing
-an issue in the kernel. The file trace_entries is used to modify
+an issue in the kernel. The file buffer_size_kb is used to modify
 the size of the internal trace buffers. The number listed
 is the number of entries that can be recorded per CPU. To know
 the full size, multiply the number of possible CPUS with the
 number of entries.
 
- # cat /debug/tracing/trace_entries
-65620
+ # cat /debug/tracing/buffer_size_kb
+1408 (units kilobytes)
 
 Note, to modify this, you must have tracing completely disabled. To do that,
 echo "nop" into the current_tracer. If the current_tracer is not set
 to "nop", an EINVAL error will be returned.
 
  # echo nop > /debug/tracing/current_tracer
- # echo 100000 > /debug/tracing/trace_entries
- # cat /debug/tracing/trace_entries
-100045
-
-
-Notice that we echoed in 100,000 but the size is 100,045. The entries
-are held in individual pages. It allocates the number of pages it takes
-to fulfill the request. If more entries may fit on the last page
-then they will be added.
-
- # echo 1 > /debug/tracing/trace_entries
- # cat /debug/tracing/trace_entries
-85
-
-This shows us that 85 entries can fit in a single page.
+ # echo 10000 > /debug/tracing/buffer_size_kb
+ # cat /debug/tracing/buffer_size_kb
+10000 (units kilobytes)
 
 The number of pages which will be allocated is limited to a percentage
 of available memory. Allocating too much will produce an error.
 
- # echo 1000000000000 > /debug/tracing/trace_entries
+ # echo 1000000000000 > /debug/tracing/buffer_size_kb
 -bash: echo: write error: Cannot allocate memory
- # cat /debug/tracing/trace_entries
+ # cat /debug/tracing/buffer_size_kb
 85
 
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index beb21a51e1ef..54cb9a7d15e5 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -179,8 +179,7 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
 
         if (ftrace_enabled) {
                 /* If we only have one func left, then call that directly */
-                if (ftrace_list == &ftrace_list_end ||
-                    ftrace_list->next == &ftrace_list_end)
+                if (ftrace_list->next == &ftrace_list_end)
                         ftrace_trace_function = ftrace_list->func;
         }
 
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 2d6c2cf0c3bc..caa4fda50f8a 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -533,6 +533,12 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
         LIST_HEAD(pages);
         int i, cpu;
 
+        /*
+         * Always succeed at resizing a non-existent buffer:
+         */
+        if (!buffer)
+                return size;
+
         size = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
         size *= BUF_PAGE_SIZE;
         buffer_size = buffer->pages * BUF_PAGE_SIZE;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4bf070bb5272..4a904623e05d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -204,8 +204,9 @@ static DEFINE_MUTEX(trace_types_lock);
 /* trace_wait is a waitqueue for tasks blocked on trace_poll */
 static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
 
-/* trace_flags holds iter_ctrl options */
-unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK;
+/* trace_flags holds trace_options default values */
+unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
+        TRACE_ITER_ANNOTATE;
 
 /**
  * trace_wake_up - wake up tasks waiting for trace input
@@ -261,6 +262,7 @@ static const char *trace_options[] = {
 #ifdef CONFIG_BRANCH_TRACER
         "branch",
 #endif
+        "annotate",
         NULL
 };
 
@@ -1113,6 +1115,7 @@ void tracing_stop_function_trace(void)
 
 enum trace_file_type {
         TRACE_FILE_LAT_FMT      = 1,
+        TRACE_FILE_ANNOTATE     = 2,
 };
 
 static void trace_iterator_increment(struct trace_iterator *iter, int cpu)
@@ -1532,6 +1535,12 @@ static void test_cpu_buff_start(struct trace_iterator *iter)
 {
         struct trace_seq *s = &iter->seq;
 
+        if (!(trace_flags & TRACE_ITER_ANNOTATE))
+                return;
+
+        if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
+                return;
+
         if (cpu_isset(iter->cpu, iter->started))
                 return;
 
@@ -2132,6 +2141,11 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
         iter->trace = current_trace;
         iter->pos = -1;
 
+        /* Annotate start of buffers if we had overruns */
+        if (ring_buffer_overruns(iter->tr->buffer))
+                iter->iter_flags |= TRACE_FILE_ANNOTATE;
+
+
         for_each_tracing_cpu(cpu) {
 
                 iter->buffer_iter[cpu] =
@@ -2411,7 +2425,7 @@ static struct file_operations tracing_cpumask_fops = {
 };
 
 static ssize_t
-tracing_iter_ctrl_read(struct file *filp, char __user *ubuf,
+tracing_trace_options_read(struct file *filp, char __user *ubuf,
                        size_t cnt, loff_t *ppos)
 {
         char *buf;
@@ -2448,7 +2462,7 @@ tracing_iter_ctrl_read(struct file *filp, char __user *ubuf,
 }
 
 static ssize_t
-tracing_iter_ctrl_write(struct file *filp, const char __user *ubuf,
+tracing_trace_options_write(struct file *filp, const char __user *ubuf,
                         size_t cnt, loff_t *ppos)
 {
         char buf[64];
@@ -2493,8 +2507,8 @@ tracing_iter_ctrl_write(struct file *filp, const char __user *ubuf,
 
 static struct file_operations tracing_iter_fops = {
         .open           = tracing_open_generic,
-        .read           = tracing_iter_ctrl_read,
-        .write          = tracing_iter_ctrl_write,
+        .read           = tracing_trace_options_read,
+        .write          = tracing_trace_options_write,
 };
 
 static const char readme_msg[] =
@@ -2508,9 +2522,9 @@ static const char readme_msg[] =
         "# echo sched_switch > /debug/tracing/current_tracer\n"
         "# cat /debug/tracing/current_tracer\n"
         "sched_switch\n"
-        "# cat /debug/tracing/iter_ctrl\n"
+        "# cat /debug/tracing/trace_options\n"
         "noprint-parent nosym-offset nosym-addr noverbose\n"
-        "# echo print-parent > /debug/tracing/iter_ctrl\n"
+        "# echo print-parent > /debug/tracing/trace_options\n"
         "# echo 1 > /debug/tracing/tracing_enabled\n"
         "# cat /debug/tracing/trace > /tmp/trace.txt\n"
         "echo 0 > /debug/tracing/tracing_enabled\n"
@@ -2905,7 +2919,7 @@ tracing_entries_read(struct file *filp, char __user *ubuf,
         char buf[64];
         int r;
 
-        r = sprintf(buf, "%lu\n", tr->entries);
+        r = sprintf(buf, "%lu\n", tr->entries >> 10);
         return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
 }
 
@@ -2945,6 +2959,9 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
                         atomic_inc(&max_tr.data[cpu]->disabled);
         }
 
+        /* value is in KB */
+        val <<= 10;
+
         if (val != global_trace.entries) {
                 ret = ring_buffer_resize(global_trace.buffer, val);
                 if (ret < 0) {
@@ -3145,10 +3162,10 @@ static __init int tracer_init_debugfs(void)
         if (!entry)
                 pr_warning("Could not create debugfs 'tracing_enabled' entry\n");
 
-        entry = debugfs_create_file("iter_ctrl", 0644, d_tracer,
+        entry = debugfs_create_file("trace_options", 0644, d_tracer,
                                     NULL, &tracing_iter_fops);
         if (!entry)
-                pr_warning("Could not create debugfs 'iter_ctrl' entry\n");
+                pr_warning("Could not create debugfs 'trace_options' entry\n");
 
         entry = debugfs_create_file("tracing_cpumask", 0644, d_tracer,
                                     NULL, &tracing_cpumask_fops);
@@ -3198,11 +3215,11 @@ static __init int tracer_init_debugfs(void)
                 pr_warning("Could not create debugfs "
                            "'trace_pipe' entry\n");
 
-        entry = debugfs_create_file("trace_entries", 0644, d_tracer,
+        entry = debugfs_create_file("buffer_size_kb", 0644, d_tracer,
                                     &global_trace, &tracing_entries_fops);
         if (!entry)
                 pr_warning("Could not create debugfs "
-                           "'trace_entries' entry\n");
+                           "'buffer_size_kb' entry\n");
 
         entry = debugfs_create_file("trace_marker", 0220, d_tracer,
                                     NULL, &tracing_mark_fops);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9e015f5bea1d..790ea8c0e1f3 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -473,6 +473,7 @@ enum trace_iterator_flags {
 #ifdef CONFIG_BRANCH_TRACER
         TRACE_ITER_BRANCH               = 0x1000,
 #endif
+        TRACE_ITER_ANNOTATE             = 0x2000,
 };
 
 /*