linux-kernel - [PATCH 0/2] tracing: Clean up trigger code my merging structures

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Message-ID: <20251119031042.328864818@kernel.org>
Date: Tue, 18 Nov 2025 22:10:42 -0500
From: Steven Rostedt <rostedt@...nel.org>
To: linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Tom Zanussi <zanussi@...nel.org>
Subject: [PATCH 0/2] tracing: Clean up trigger code my merging structures

The struct event_command has a callback function called get_trigger_ops().
This callback returns the "trigger_ops" to use for the trigger. These ops
define the trigger function, how to init the trigger, how to print the
trigger and how to free it.

The only reason there's a callback function to get these ops is because
some triggers have two types of operations. One is an "always on"
operation, and the other is a "count down" operation. If a user passes in
a parameter to say how many times the trigger should execute. For example:

  echo stacktrace:5 > events/kmem/kmem_cache_alloc/trigger

It will trigger the stacktrace for the first 5 times the kmem_cache_alloc
event is hit.

Instead of having two different trigger_ops since the only difference
between them is the tigger itself (the print, init and free functions are
all the same), just use a single ops that the event_command points to and
add a function field to the trigger_ops to have a count_func.

When a trigger is added to an event, if there's a count attached to it and
the trigger ops has the count_func field, the data allocated to represent
this trigger will have a new flag set called COUNT.

Then when the trigger executes, it will check if the COUNT data flag is
set, and if so, it will call the ops count_func(). If that returns false,
it returns without executing the trigger.

After making the struct event_trigger_ops be mapped one to one with the
struct event_command, merge the former into the latter.

Steven Rostedt (2):
      tracing: Remove get_trigger_ops() and add count_func() from trigger ops
      tracing: Merge struct event_trigger_ops into struct event_command

----
 kernel/trace/trace.h                | 124 ++++++-------
 kernel/trace/trace_eprobe.c         |  19 +-
 kernel/trace/trace_events_hist.c    | 143 +++++----------
 kernel/trace/trace_events_trigger.c | 344 +++++++++++++-----------------------
 4 files changed, 231 insertions(+), 399 deletions(-)