ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 82 insertions, 0 deletions

diff --git a/tools/perf/Documentation/perf-data.txt b/tools/perf/Documentation/perf-data.txt
new file mode 100644
index 000000000..20f178d61
--- /dev/null
+++ b/tools/perf/Documentation/perf-data.txt
@@ -0,0 +1,82 @@
+perf-data(1)
+============
+
+NAME
+----
+perf-data - Data file related processing
+
+SYNOPSIS
+--------
+[verse]
+'perf data' [<common options>] <command> [<options>]",
+
+DESCRIPTION
+-----------
+Data file related processing.
+
+COMMANDS
+--------
+convert::
+	Converts perf data file into another format.
+	It's possible to set data-convert debug variable to get debug messages from conversion,
+	like:
+	  perf --debug data-convert data convert ...
+
+OPTIONS for 'convert'
+---------------------
+--to-ctf::
+	Triggers the CTF conversion, specify the path of CTF data directory.
+
+--to-json::
+	Triggers JSON conversion. Specify the JSON filename to output.
+
+--tod::
+	Convert time to wall clock time.
+
+-i::
+	Specify input perf data file path.
+
+-f::
+--force::
+	Don't complain, do it.
+
+--time::
+	Only convert samples within given time window: <start>,<stop>. Times
+	have the format seconds.nanoseconds. If start is not given (i.e. time
+	string is ',x.y') then analysis starts at the beginning of the file. If
+	stop time is not given (i.e. time string is 'x.y,') then analysis goes
+	to end of file. Multiple ranges can be separated by spaces, which
+	requires the argument to be quoted e.g. --time "1234.567,1234.789 1235,"
+
+	Also support time percent with multiple time ranges. Time string is
+	'a%/n,b%/m,...' or 'a%-b%,c%-%d,...'.
+
+	For example:
+	Select the second 10% time slice:
+
+	  perf data convert --to-json out.json --time 10%/2
+
+	Select from 0% to 10% time slice:
+
+	  perf data convert --to-json out.json --time 0%-10%
+
+	Select the first and second 10% time slices:
+
+	  perf data convert --to-json out.json --time 10%/1,10%/2
+
+	Select from 0% to 10% and 30% to 40% slices:
+
+	  perf data convert --to-json out.json --time 0%-10%,30%-40%
+
+-v::
+--verbose::
+        Be more verbose (show counter open errors, etc).
+
+--all::
+	Convert all events, including non-sample events (comm, fork, ...), to output.
+	Default is off, only convert samples.
+
+SEE ALSO
+--------
+linkperf:perf[1]
+[1] Common Trace Format - http://www.efficios.com/ctf