linux-trace-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Steven Rostedt <rostedt@goodmis.org>
To: LKML <linux-kernel@vger.kernel.org>,
	Linux trace kernel <linux-trace-kernel@vger.kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Arnd Bergmann <arnd@kernel.org>
Subject: [PATCH] tracing: Fix ifdef of snapshots to not prevent last_boot_info file
Date: Fri, 19 Jul 2024 10:13:12 -0400	[thread overview]
Message-ID: <20240719101312.3d4ac707@rorschach.local.home> (raw)

From: Steven Rostedt <rostedt@goodmis.org>

The mapping of the ring buffer to memory allocated at boot up will also
expose a "last_boot_info" to help tooling to read the raw data from the
last boot. As instances that have their ring buffer mapped to fixed
memory cannot perform snapshots, they can either have the "snapshot" file
or the "last_boot_info" file, but not both.

The code that added the "last_boot_info" file failed to notice that the
"snapshot" creation was inside a "#ifdef CONFIG_TRACER_SNAPSHOT" and
incorrectly placed the creation of the "last_boot_info" file within the
ifdef block. Not only does it cause a warning when CONFIG_TRACER_SNAPSHOT
is not enabled, it also incorrectly prevents the file from appearing.

Link: https://lore.kernel.org/all/20240719102640.718554-1-arnd@kernel.org/

Reported-by: Arnd Bergmann <arnd@kernel.org>
Fixes: 7a1d1e4b9639 ("tracing/ring-buffer: Add last_boot_info file to boot instance")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5462fb10ff64..0d1841b3363e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9828,15 +9828,15 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 	if (ftrace_create_function_files(tr, d_tracer))
 		MEM_FAIL(1, "Could not allocate function filter files");
 
-#ifdef CONFIG_TRACER_SNAPSHOT
 	if (tr->range_addr_start) {
 		trace_create_file("last_boot_info", TRACE_MODE_READ, d_tracer,
 				  tr, &last_boot_fops);
+#ifdef CONFIG_TRACER_SNAPSHOT
 	} else {
 		trace_create_file("snapshot", TRACE_MODE_WRITE, d_tracer,
 				  tr, &snapshot_fops);
-	}
 #endif
+	}
 
 	trace_create_file("error_log", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_err_log_fops);
-- 
2.43.0


                 reply	other threads:[~2024-07-19 14:13 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20240719101312.3d4ac707@rorschach.local.home \
    --to=rostedt@goodmis.org \
    --cc=arnd@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-trace-kernel@vger.kernel.org \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=mhiramat@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).