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, 89 insertions, 0 deletions

diff --git a/tools/perf/Documentation/perf-test.txt b/tools/perf/Documentation/perf-test.txt
new file mode 100644
index 000000000..859df74e6
--- /dev/null
+++ b/tools/perf/Documentation/perf-test.txt
@@ -0,0 +1,89 @@
+perf-test(1)
+============
+
+NAME
+----
+perf-test - Runs sanity tests.
+
+SYNOPSIS
+--------
+[verse]
+'perf test [<options>] [{list <test-name-fragment>|[<test-name-fragments>|<test-numbers>]}]'
+
+DESCRIPTION
+-----------
+This command does assorted sanity tests, initially through linked routines but
+also will look for a directory with more tests in the form of scripts.
+
+To get a list of available tests use 'perf test list', specifying a test name
+fragment will show all tests that have it.
+
+To run just specific tests, inform test name fragments or the numbers obtained
+from 'perf test list'.
+
+OPTIONS
+-------
+-s::
+--skip::
+	Tests to skip (comma separated numeric list).
+
+-v::
+-vv::
+-vvv::
+--verbose::
+	With a single '-v', verbose level 1, only failing test output
+	is displayed. With '-vv' and higher all test output is shown.
+
+-S::
+--sequential::
+	Run all tests one after the other. By default "exclusive"
+	tests are run sequentially, but other tests are run in
+	parallel to speed execution.
+
+-r::
+--runs-per-test::
+	Run each test the given number of times, by default once. This
+	option can be useful to determine if a test is flaky.
+
+-F::
+--dont-fork::
+	Do not fork child for each test, run all tests within single process, this
+	sets sequential mode.
+
+--dso::
+	Specify a DSO for the "Symbols" test.
+
+-w::
+--workload=::
+	Run a built-in workload, to list them use '--list-workloads', current
+	ones include: noploop, thloop, leafloop, sqrtloop, brstack, datasym,
+	context_switch_loop, deterministic, named_threads, landlock and
+	callchain.
+
+	Used with the shell script regression tests.
+
+	Some accept an extra parameter:
+
+		seconds: leafloop, noploop, sqrtloop, thloop
+		nrloops: brstack, context_switch_loop
+
+	'named_threads' accepts the number of threads and the number of loops to
+	do in each thread.
+
+	The datasym, landlock, deterministic and callchain workloads don't accept
+	any.
+
+--list-workloads::
+	List the available workloads to use with -w/--workload.
+
+--record-ctl=fifo:ctl-fifo[,ack-fifo]::
+	This option is used to communicate with a perf record session in order
+	to control the recording scope to only the workload and avoid recording
+	setup and teardown code. When specifying this option, the same FIFO path
+	must be specified in the record session via:
+
+	  perf record -D -1 --control=fifo:ctl-fifo[,ack-fifo] ...
+
+	Perf test sends 'enable' and 'disable' commands through ctl-fifo to
+	control event recording. If 'ack-fifo' is provided, the workload runner
+	waits for an 'ack' response after each command.