Merge tag 'trace-rtla-v7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull RTLA updates from Steven Rostedt:

 - Remove unused function declarations

   Some functions were removed in recent code consolidation 6.18, but
   their prototypes were not removed from headers. Remove them.

 - Set stop threshold after enabling instances

   Prefer recording samples without stopping on them on the start of
   tracing to stopping on samples that are never recorded. This fixes
   flakiness of some RTLA tests and unifies behavior of sample
   collection between tracefs mode and BPF mode.

 - Consolidate usage help message implementation

   RTLA tools (osnoise-top, osnoise-hist, timerlat-top, timerlat-hist)
   each implement usage help individually. Move common logic between
   them into a new function to reduce code duplication.

 - Add BPF actions feature

   Add option --bpf-action to attach a BPF program (passed as filename
   of its ELF representation) to be executed via BPF tail call at
   latency threshold.

 - Consolidate command line option parsing

   Each RTLA tool implements the parsing of command line options
   individually. Now that we have a common structure for parameters,
   unify the parsing of those options common among all four tools into
   one function.

 - De-duplicate cgroup common code

   Two functions in utils.c, setting cgroup for comm and setting cgroup
   for pid, duplicate code for constructing the cgroup path. Extract it
   to a new helper function.

 - String and error handling fixes and cleanups

   There were several instances of unsafe string and error handling that
   could cause invalid memory access; fix them. Also, remove a few
   unused headers, update .gitignore, and deduplicate code.

* tag 'trace-rtla-v7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (30 commits)
  rtla: Fix parse_cpu_set() bug introduced by strtoi()
  rtla: Fix parse_cpu_set() return value documentation
  rtla: Ensure null termination after read operations in utils.c
  rtla: Make stop_tracing variable volatile
  rtla: Add generated output files to gitignore
  rtla: Fix NULL pointer dereference in actions_parse
  rtla: Remove unused headers
  rtla: Remove redundant memset after calloc
  rtla: Use standard exit codes for result enum
  rtla: Replace atoi() with a robust strtoi()
  rtla: Introduce for_each_action() helper
  tools/rtla: Deduplicate cgroup path opening code
  tools/rtla: Consolidate -H/--house-keeping option parsing
  tools/rtla: Consolidate -P/--priority option parsing
  tools/rtla: Consolidate -e/--event option parsing
  tools/rtla: Consolidate -d/--duration option parsing
  tools/rtla: Consolidate -D/--debug option parsing
  tools/rtla: Consolidate -C/--cgroup option parsing
  tools/rtla: Consolidate -c/--cpus option parsing
  tools/rtla: Add common_parse_options()
  ...

1 files changed, 19 insertions, 1 deletions

diff --git a/Documentation/tools/rtla/common_timerlat_options.txt b/Documentation/tools/rtla/common_timerlat_options.txt
index 33070b264cae..07a285fcf7cf 100644
--- a/Documentation/tools/rtla/common_timerlat_options.txt
+++ b/Documentation/tools/rtla/common_timerlat_options.txt
@@ -64,4 +64,22 @@
 
         Set timerlat to run without workload, waiting for the user to dispatch a per-cpu
         task that waits for a new period on the tracing/osnoise/per_cpu/cpu$ID/timerlat_fd.
-        See linux/tools/rtla/sample/timerlat_load.py for an example of user-load code.
+        See linux/tools/rtla/example/timerlat_load.py for an example of user-load code.
+
+**--bpf-action** *bpf-program*
+
+        Loads a BPF program from an ELF file and executes it when a latency threshold is exceeded.
+
+        The BPF program must be a valid ELF file loadable with libbpf. The program must contain
+        a function named ``action_handler``, stored in an ELF section with the ``tp_`` prefix.
+        The prefix is used by libbpf to set BPF program type to BPF_PROG_TYPE_TRACEPOINT.
+
+        The program receives a ``struct trace_event_raw_timerlat_sample`` parameter
+        containing timerlat sample data.
+
+        An example is provided in ``tools/tracing/rtla/example/timerlat_bpf_action.c``.
+        This example demonstrates how to create a BPF program that prints latency information using
+        bpf_trace_printk() when a threshold is exceeded.
+
+        **Note**: BPF actions require BPF support to be available. If BPF is not available
+        or disabled, the tool falls back to tracefs mode and BPF actions are not supported.