[PATCH v2 0/4] tracing: Addition of tracing instances via kernel command line

[Steven Rostedt <rostedt@goodmis.org>]

Instance creation can happen with the bootconfig but there's currently
no way to create and enable instances via the normal command line.

This series fixes that.

 trace_instance=foo,sched_switch,sched_waking ftrace_boot_snapshot=foo

The above creates a "foo" instance at early start up and enables
the sched_switch and sched_waking events. Then at the end of boot up
a snapshot is taken so that user space does not overwrite the boot
up data.

Changes since v1: https://lore.kernel.org/linux-trace-kernel/20230111145636.450953217@goodmis.org/
 - Fixed document grammar (Randy Dunlap)
 - Removed extra workqueue.h include (Ross Zwisler)
 - Use sizeof(boot_instance_info) than using COMMAND_LINE_SIZE)
 - Remove unneeded @ip in kernel-doc (Ross Zwisler)
 - Make stub function for do_allocate_snapshot() for !CONFIG_TRACER_MAX_TRACE (kernel test robot)
 - Compare strstr() to NULL and not zero (kernel test robot)
 - Use sizeof(boot_snapshot_info) instead of COMMAND_LINE_SIZE (Ross Zwisler)

Steven Rostedt (Google) (4):
      tracing: Add creation of instances at boot command line
      tracing: Add enabling of events to boot instances
      tracing: Add trace_array_puts() to write into instance
      tracing: Allow boot instances to have snapshot buffers

----
 Documentation/admin-guide/bootconfig.rst        |   6 +-
 Documentation/admin-guide/kernel-parameters.txt |  29 +++++
 include/linux/bootconfig.h                      |   2 +-
 include/linux/trace.h                           |  12 ++
 init/Kconfig                                    |  13 --
 init/main.c                                     |   2 +-
 kernel/trace/trace.c                            | 160 +++++++++++++++++++++---
 kernel/trace/trace.h                            |   2 +
 kernel/trace/trace_events.c                     |   9 +-
 9 files changed, 193 insertions(+), 42 deletions(-)