Merge tag 'trace-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "New tracing features:

   - The ring buffer is no longer disabled when reading the trace file.

     The trace_pipe file was made to be used for live tracing and
     reading as it acted like the normal producer/consumer. As the trace
     file would not consume the data, the easy way of handling it was to
     just disable writes to the ring buffer.

     This came to a surprise to the BPF folks who complained about lost
     events due to reading. This is no longer an issue. If someone wants
     to keep the old disabling there's a new option "pause-on-trace"
     that can be set.

   - New set_ftrace_notrace_pid file. PIDs in this file will not be
     traced by the function tracer.

     Similar to set_ftrace_pid, which makes the function tracer only
     trace those tasks with PIDs in the file, the set_ftrace_notrace_pid
     does the reverse.

   - New set_event_notrace_pid file. PIDs in this file will cause events
     not to be traced if triggered by a task with a matching PID.

     Similar to the set_event_pid file but will not be traced. Note,
     sched_waking and sched_switch events may still be traced if one of
     the tasks referenced by those events contains a PID that is allowed
     to be traced.

  Tracing related features:

   - New bootconfig option, that is attached to the initrd file.

     If bootconfig is on the command line, then the initrd file is
     searched looking for a bootconfig appended at the end.

   - New GPU tracepoint infrastructure to help the gfx drivers to get
     off debugfs (acked by Greg Kroah-Hartman)

  And other minor updates and fixes"

* tag 'trace-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (27 commits)
  tracing: Do not allocate buffer in trace_find_next_entry() in atomic
  tracing: Add documentation on set_ftrace_notrace_pid and set_event_notrace_pid
  selftests/ftrace: Add test to test new set_event_notrace_pid file
  selftests/ftrace: Add test to test new set_ftrace_notrace_pid file
  tracing: Create set_event_notrace_pid to not trace tasks
  ftrace: Create set_ftrace_notrace_pid to not trace tasks
  ftrace: Make function trace pid filtering a bit more exact
  ftrace/kprobe: Show the maxactive number on kprobe_events
  tracing: Have the document reflect that the trace file keeps tracing enabled
  ring-buffer/tracing: Have iterator acknowledge dropped events
  tracing: Do not disable tracing when reading the trace file
  ring-buffer: Do not disable recording when there is an iterator
  ring-buffer: Make resize disable per cpu buffer instead of total buffer
  ring-buffer: Optimize rb_iter_head_event()
  ring-buffer: Do not die if rb_iter_peek() fails more than thrice
  ring-buffer: Have rb_iter_head_event() handle concurrent writer
  ring-buffer: Add page_stamp to iterator for synchronization
  ring-buffer: Rename ring_buffer_read() to read_buffer_iter_advance()
  ring-buffer: Have ring_buffer_empty() not depend on tracing stopped
  tracing: Save off entry when peeking at next entry
  ...

1 files changed, 66 insertions, 16 deletions

diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
index ff658e27d25b..3b5614b1d1a5 100644
--- a/Documentation/trace/ftrace.rst
+++ b/Documentation/trace/ftrace.rst
@@ -125,10 +125,13 @@ of ftrace. Here is a list of some of the key files:
   trace:
 
 	This file holds the output of the trace in a human
-	readable format (described below). Note, tracing is temporarily
-	disabled when the file is open for reading. Once all readers
-	are closed, tracing is re-enabled. Opening this file for
+	readable format (described below). Opening this file for
 	writing with the O_TRUNC flag clears the ring buffer content.
+        Note, this file is not a consumer. If tracing is off
+        (no tracer running, or tracing_on is zero), it will produce
+        the same output each time it is read. When tracing is on,
+        it may produce inconsistent results as it tries to read
+        the entire buffer without consuming it.
 
   trace_pipe:
 
@@ -142,9 +145,7 @@ of ftrace. Here is a list of some of the key files:
 	will not be read again with a sequential read. The
 	"trace" file is static, and if the tracer is not
 	adding more data, it will display the same
-	information every time it is read. Unlike the
-	"trace" file, opening this file for reading will not
-	temporarily disable tracing.
+	information every time it is read.
 
   trace_options:
 
@@ -262,6 +263,20 @@ of ftrace. Here is a list of some of the key files:
 	traced by the function tracer as well. This option will also
 	cause PIDs of tasks that exit to be removed from the file.
 
+  set_ftrace_notrace_pid:
+
+        Have the function tracer ignore threads whose PID are listed in
+        this file.
+
+        If the "function-fork" option is set, then when a task whose
+	PID is listed in this file forks, the child's PID will
+	automatically be added to this file, and the child will not be
+	traced by the function tracer as well. This option will also
+	cause PIDs of tasks that exit to be removed from the file.
+
+        If a PID is in both this file and "set_ftrace_pid", then this
+        file takes precedence, and the thread will not be traced.
+
   set_event_pid:
 
 	Have the events only trace a task with a PID listed in this file.
@@ -273,6 +288,19 @@ of ftrace. Here is a list of some of the key files:
 	cause the PIDs of tasks to be removed from this file when the task
 	exits.
 
+  set_event_notrace_pid:
+
+	Have the events not trace a task with a PID listed in this file.
+	Note, sched_switch and sched_wakeup will trace threads not listed
+	in this file, even if a thread's PID is in the file if the
+        sched_switch or sched_wakeup events also trace a thread that should
+        be traced.
+
+	To have the PIDs of children of tasks with their PID in this file
+	added on fork, enable the "event-fork" option. That option will also
+	cause the PIDs of tasks to be removed from this file when the task
+	exits.
+
   set_graph_function:
 
 	Functions listed in this file will cause the function graph
@@ -1125,6 +1153,12 @@ Here are the available options:
 	the trace displays additional information about the
 	latency, as described in "Latency trace format".
 
+  pause-on-trace
+	When set, opening the trace file for read, will pause
+	writing to the ring buffer (as if tracing_on was set to zero).
+	This simulates the original behavior of the trace file.
+	When the file is closed, tracing will be enabled again.
+
   record-cmd
 	When any event or tracer is enabled, a hook is enabled
 	in the sched_switch trace point to fill comm cache
@@ -1176,6 +1210,8 @@ Here are the available options:
 	tasks fork. Also, when tasks with PIDs in set_event_pid exit,
 	their PIDs will be removed from the file.
 
+        This affects PIDs listed in set_event_notrace_pid as well.
+
   function-trace
 	The latency tracers will enable function tracing
 	if this option is enabled (default it is). When
@@ -1190,6 +1226,8 @@ Here are the available options:
 	set_ftrace_pid exit, their PIDs will be removed from the
 	file.
 
+        This affects PIDs in set_ftrace_notrace_pid as well.
+
   display-graph
 	When set, the latency tracers (irqsoff, wakeup, etc) will
 	use function graph tracing instead of function tracing.
@@ -2126,6 +2164,8 @@ periodically make a CPU constantly busy with interrupts disabled.
   # cat trace
   # tracer: hwlat
   #
+  # entries-in-buffer/entries-written: 13/13   #P:8
+  #
   #                              _-----=> irqs-off
   #                             / _----=> need-resched
   #                            | / _---=> hardirq/softirq
@@ -2133,12 +2173,18 @@ periodically make a CPU constantly busy with interrupts disabled.
   #                            ||| /     delay
   #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
   #              | |       |   ||||       |         |
-             <...>-3638  [001] d... 19452.055471: #1     inner/outer(us):   12/14    ts:1499801089.066141940
-             <...>-3638  [003] d... 19454.071354: #2     inner/outer(us):   11/9     ts:1499801091.082164365
-             <...>-3638  [002] dn.. 19461.126852: #3     inner/outer(us):   12/9     ts:1499801098.138150062
-             <...>-3638  [001] d... 19488.340960: #4     inner/outer(us):    8/12    ts:1499801125.354139633
-             <...>-3638  [003] d... 19494.388553: #5     inner/outer(us):    8/12    ts:1499801131.402150961
-             <...>-3638  [003] d... 19501.283419: #6     inner/outer(us):    0/12    ts:1499801138.297435289 nmi-total:4 nmi-count:1
+             <...>-1729  [001] d...   678.473449: #1     inner/outer(us):   11/12    ts:1581527483.343962693 count:6
+             <...>-1729  [004] d...   689.556542: #2     inner/outer(us):   16/9     ts:1581527494.889008092 count:1
+             <...>-1729  [005] d...   714.756290: #3     inner/outer(us):   16/16    ts:1581527519.678961629 count:5
+             <...>-1729  [001] d...   718.788247: #4     inner/outer(us):    9/17    ts:1581527523.889012713 count:1
+             <...>-1729  [002] d...   719.796341: #5     inner/outer(us):   13/9     ts:1581527524.912872606 count:1
+             <...>-1729  [006] d...   844.787091: #6     inner/outer(us):    9/12    ts:1581527649.889048502 count:2
+             <...>-1729  [003] d...   849.827033: #7     inner/outer(us):   18/9     ts:1581527654.889013793 count:1
+             <...>-1729  [007] d...   853.859002: #8     inner/outer(us):    9/12    ts:1581527658.889065736 count:1
+             <...>-1729  [001] d...   855.874978: #9     inner/outer(us):    9/11    ts:1581527660.861991877 count:1
+             <...>-1729  [001] d...   863.938932: #10    inner/outer(us):    9/11    ts:1581527668.970010500 count:1 nmi-total:7 nmi-count:1
+             <...>-1729  [007] d...   878.050780: #11    inner/outer(us):    9/12    ts:1581527683.385002600 count:1 nmi-total:5 nmi-count:1
+             <...>-1729  [007] d...   886.114702: #12    inner/outer(us):    9/12    ts:1581527691.385001600 count:1
 
 
 The above output is somewhat the same in the header. All events will have
@@ -2148,7 +2194,7 @@ interrupts disabled 'd'. Under the FUNCTION title there is:
 	This is the count of events recorded that were greater than the
 	tracing_threshold (See below).
 
- inner/outer(us):   12/14
+ inner/outer(us):   11/11
 
       This shows two numbers as "inner latency" and "outer latency". The test
       runs in a loop checking a timestamp twice. The latency detected within
@@ -2156,11 +2202,15 @@ interrupts disabled 'd'. Under the FUNCTION title there is:
       after the previous timestamp and the next timestamp in the loop is
       the "outer latency".
 
- ts:1499801089.066141940
+ ts:1581527483.343962693
+
+      The absolute timestamp that the first latency was recorded in the window.
+
+ count:6
 
-      The absolute timestamp that the event happened.
+      The number of times a latency was detected during the window.
 
- nmi-total:4 nmi-count:1
+ nmi-total:7 nmi-count:1
 
       On architectures that support it, if an NMI comes in during the
       test, the time spent in NMI is reported in "nmi-total" (in