Merge tag 'trace-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

 - Added option for per CPU threads to the hwlat tracer

 - Have hwlat tracer handle hotplug CPUs

 - New tracer: osnoise, that detects latency caused by interrupts,
   softirqs and scheduling of other tasks.

 - Added timerlat tracer that creates a thread and measures in detail
   what sources of latency it has for wake ups.

 - Removed the "success" field of the sched_wakeup trace event. This has
   been hardcoded as "1" since 2015, no tooling should be looking at it
   now. If one exists, we can revert this commit, fix that tool and try
   to remove it again in the future.

 - tgid mapping fixed to handle more than PID_MAX_DEFAULT pids/tgids.

 - New boot command line option "tp_printk_stop", as tp_printk causes
   trace events to write to console. When user space starts, this can
   easily live lock the system. Having a boot option to stop just after
   boot up is useful to prevent that from happening.

 - Have ftrace_dump_on_oops boot command line option take numbers that
   match the numbers shown in /proc/sys/kernel/ftrace_dump_on_oops.

 - Bootconfig clean ups, fixes and enhancements.

 - New ktest script that tests bootconfig options.

 - Add tracepoint_probe_register_may_exist() to register a tracepoint
   without triggering a WARN*() if it already exists. BPF has a path
   from user space that can do this. All other paths are considered a
   bug.

 - Small clean ups and fixes

* tag 'trace-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (49 commits)
  tracing: Resize tgid_map to pid_max, not PID_MAX_DEFAULT
  tracing: Simplify & fix saved_tgids logic
  treewide: Add missing semicolons to __assign_str uses
  tracing: Change variable type as bool for clean-up
  trace/timerlat: Fix indentation on timerlat_main()
  trace/osnoise: Make 'noise' variable s64 in run_osnoise()
  tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing
  tracing: Fix spelling in osnoise tracer "interferences" -> "interference"
  Documentation: Fix a typo on trace/osnoise-tracer
  trace/osnoise: Fix return value on osnoise_init_hotplug_support
  trace/osnoise: Make interval u64 on osnoise_main
  trace/osnoise: Fix 'no previous prototype' warnings
  tracing: Have osnoise_main() add a quiescent state for task rcu
  seq_buf: Make trace_seq_putmem_hex() support data longer than 8
  seq_buf: Fix overflow in seq_buf_putmem_hex()
  trace/osnoise: Support hotplug operations
  trace/hwlat: Support hotplug operations
  trace/hwlat: Protect kdata->kthread with get/put_online_cpus
  trace: Add timerlat tracer
  trace: Add osnoise tracer
  ...

2 files changed, 39 insertions, 4 deletions

diff --git a/Documentation/admin-guide/bootconfig.rst b/Documentation/admin-guide/bootconfig.rst
index 452b7dcd7f6b..6a79f2e59396 100644
--- a/Documentation/admin-guide/bootconfig.rst
+++ b/Documentation/admin-guide/bootconfig.rst
@@ -89,13 +89,35 @@ you can use ``+=`` operator. For example::
 
 In this case, the key ``foo`` has ``bar``, ``baz`` and ``qux``.
 
-However, a sub-key and a value can not co-exist under a parent key.
-For example, following config is NOT allowed.::
+Moreover, sub-keys and a value can coexist under a parent key.
+For example, following config is allowed.::
 
  foo = value1
- foo.bar = value2 # !ERROR! subkey "bar" and value "value1" can NOT co-exist
- foo.bar := value2 # !ERROR! even with the override operator, this is NOT allowed.
+ foo.bar = value2
+ foo := value3 # This will update foo's value.
+
+Note, since there is no syntax to put a raw value directly under a
+structured key, you have to define it outside of the brace. For example::
+
+ foo {
+     bar = value1
+     bar {
+         baz = value2
+         qux = value3
+     }
+ }
+
+Also, the order of the value node under a key is fixed. If there
+are a value and subkeys, the value is always the first child node
+of the key. Thus if user specifies subkeys first, e.g.::
+
+ foo.bar = value1
+ foo = value2
+
+In the program (and /proc/bootconfig), it will be shown as below::
 
+ foo = value2
+ foo.bar = value1
 
 Comments
 --------
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 0081d83457e8..d6717b747694 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5672,12 +5672,25 @@
 			Note, echoing 1 into this file without the
 			tracepoint_printk kernel cmdline option has no effect.
 
+			The tp_printk_stop_on_boot (see below) can also be used
+			to stop the printing of events to console at
+			late_initcall_sync.
+
 			** CAUTION **
 
 			Having tracepoints sent to printk() and activating high
 			frequency tracepoints such as irq or sched, can cause
 			the system to live lock.
 
+	tp_printk_stop_on_boot[FTRACE]
+			When tp_printk (above) is set, it can cause a lot of noise
+			on the console. It may be useful to only include the
+			printing of events during boot up, as user space may
+			make the system inoperable.
+
+			This command line option will stop the printing of events
+			to console at the late_initcall_sync() time frame.
+
 	traceoff_on_warning
 			[FTRACE] enable this option to disable tracing when a
 			warning is hit. This turns off "tracing_on". Tracing can