linux-kernel - [PATCH v2 0/2] tracing: Remove backup instance after read all

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Message-ID:  <176788217131.1398317.11144318616426272901.stgit@mhiramat.tok.corp.google.com>
Date: Thu,  8 Jan 2026 23:22:51 +0900
From: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Subject: [PATCH v2 0/2] tracing: Remove backup instance after read all

Hi,

Here is the 2nd version of the series to improve backup instances of
the persistent ring buffer. The previous version is here:

https://lore.kernel.org/all/176779714767.4193242.1978666866487010024.stgit@mhiramat.tok.corp.google.com/

In this version, I updated [1/2] to use dedicated file operations
for read only instance instead of checking on each write function.
Also use dedicated entries files for eventfs to remove writable
control files from it. So it has only 'format' and 'id' files in
readonly backup instance.

Since backup instances are a kind of snapshot of the persistent
ring buffer, it should be readonly. And if it is readonly
there is no reason to keep it after reading all data via trace_pipe
because the data has been consumed.
Thus, [1/2] makes backup instances readonly (not able to write any
events, cleanup trace, change buffer size). Also, [2/2] removes the
backup instance after consuming all data via trace_pipe.
With this improvements, even if we makes a backup instance (using
the same amount of memory of the persistent ring buffer), it will
be removed after reading the data automatically.

---

Masami Hiramatsu (Google) (2):
      tracing: Make the backup instance readonly
      tracing: Add autoremove feature to the backup instance

 kernel/trace/trace.c        |  227 +++++++++++++++++++++++++++++++++++--------
 kernel/trace/trace.h        |   20 ++++
 kernel/trace/trace_boot.c   |    5 +
 kernel/trace/trace_events.c |   75 ++++++++++----
 4 files changed, 261 insertions(+), 66 deletions(-)

--
Masami Hiramatsu (Google) <mhiramat@...nel.org>