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, 141 insertions, 0 deletions

diff --git a/tools/perf/ui/setup.c b/tools/perf/ui/setup.c
new file mode 100644
index 000000000..ff800047e
--- /dev/null
+++ b/tools/perf/ui/setup.c
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <dlfcn.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include <subcmd/pager.h>
+#include "../util/debug.h"
+#include "../util/hist.h"
+#include "ui.h"
+
+struct mutex ui__lock;
+void *perf_gtk_handle;
+int use_browser = -1;
+
+#define PERF_GTK_DSO "libperf-gtk.so"
+
+#ifdef HAVE_GTK2_SUPPORT
+
+static int setup_gtk_browser(void)
+{
+	int (*perf_ui_init)(void);
+
+	if (perf_gtk_handle)
+		return 0;
+
+	perf_gtk_handle = dlopen(PERF_GTK_DSO, RTLD_LAZY);
+	if (perf_gtk_handle == NULL) {
+		char buf[PATH_MAX];
+		scnprintf(buf, sizeof(buf), "%s/%s", LIBDIR, PERF_GTK_DSO);
+		perf_gtk_handle = dlopen(buf, RTLD_LAZY);
+	}
+	if (perf_gtk_handle == NULL)
+		return -1;
+
+	perf_ui_init = dlsym(perf_gtk_handle, "perf_gtk__init");
+	if (perf_ui_init == NULL)
+		goto out_close;
+
+	if (perf_ui_init() == 0)
+		return 0;
+
+out_close:
+	dlclose(perf_gtk_handle);
+	return -1;
+}
+
+static void exit_gtk_browser(bool wait_for_ok)
+{
+	void (*perf_ui_exit)(bool);
+
+	if (perf_gtk_handle == NULL)
+		return;
+
+	perf_ui_exit = dlsym(perf_gtk_handle, "perf_gtk__exit");
+	if (perf_ui_exit == NULL)
+		goto out_close;
+
+	perf_ui_exit(wait_for_ok);
+
+out_close:
+	dlclose(perf_gtk_handle);
+
+	perf_gtk_handle = NULL;
+}
+#else
+static inline int setup_gtk_browser(void) { return -1; }
+static inline void exit_gtk_browser(bool wait_for_ok __maybe_unused) {}
+#endif
+
+int stdio__config_color(const struct option *opt __maybe_unused,
+			const char *mode, int unset __maybe_unused)
+{
+	perf_use_color_default = perf_config_colorbool("color.ui", mode, -1);
+	return 0;
+}
+
+void setup_browser(bool fallback_to_pager)
+{
+	mutex_init(&ui__lock);
+	if (use_browser < 2 && (!isatty(1) || dump_trace))
+		use_browser = 0;
+
+	/* default to TUI */
+	if (use_browser < 0)
+		use_browser = 1;
+
+	switch (use_browser) {
+	case 2:
+		if (setup_gtk_browser() == 0)
+			break;
+		printf("GTK browser requested but could not find %s\n",
+		       PERF_GTK_DSO);
+		sleep(1);
+		use_browser = 1;
+		/* fall through */
+	case 1:
+		if (ui__init() == 0)
+			break;
+		/* fall through */
+	default:
+		use_browser = 0;
+		if (fallback_to_pager)
+			setup_pager();
+		break;
+	}
+}
+
+void exit_browser(bool wait_for_ok)
+{
+	switch (use_browser) {
+	case 2:
+		exit_gtk_browser(wait_for_ok);
+		break;
+
+	case 1:
+		ui__exit(wait_for_ok);
+		break;
+
+	default:
+		break;
+	}
+	mutex_destroy(&ui__lock);
+}
+
+void pthread__block_sigwinch(void)
+{
+	sigset_t set;
+
+	sigemptyset(&set);
+	sigaddset(&set, SIGWINCH);
+	pthread_sigmask(SIG_BLOCK, &set, NULL);
+}
+
+void pthread__unblock_sigwinch(void)
+{
+	sigset_t set;
+
+	sigemptyset(&set);
+	sigaddset(&set, SIGWINCH);
+	pthread_sigmask(SIG_UNBLOCK, &set, NULL);
+}