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, 225 insertions, 0 deletions

diff --git a/tools/gpio/lsgpio.c b/tools/gpio/lsgpio.c
new file mode 100644
index 000000000..52a0be454
--- /dev/null
+++ b/tools/gpio/lsgpio.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * lsgpio - example on how to list the GPIO lines on a system
+ *
+ * Copyright (C) 2015 Linus Walleij
+ *
+ * Usage:
+ *	lsgpio <-n device-name>
+ */
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <dirent.h>
+#include <errno.h>
+#include <string.h>
+#include <poll.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <sys/ioctl.h>
+#include <linux/gpio.h>
+
+#include "gpio-utils.h"
+
+struct gpio_flag {
+	char *name;
+	unsigned long long mask;
+};
+
+struct gpio_flag flagnames[] = {
+	{
+		.name = "used",
+		.mask = GPIO_V2_LINE_FLAG_USED,
+	},
+	{
+		.name = "input",
+		.mask = GPIO_V2_LINE_FLAG_INPUT,
+	},
+	{
+		.name = "output",
+		.mask = GPIO_V2_LINE_FLAG_OUTPUT,
+	},
+	{
+		.name = "active-low",
+		.mask = GPIO_V2_LINE_FLAG_ACTIVE_LOW,
+	},
+	{
+		.name = "open-drain",
+		.mask = GPIO_V2_LINE_FLAG_OPEN_DRAIN,
+	},
+	{
+		.name = "open-source",
+		.mask = GPIO_V2_LINE_FLAG_OPEN_SOURCE,
+	},
+	{
+		.name = "pull-up",
+		.mask = GPIO_V2_LINE_FLAG_BIAS_PULL_UP,
+	},
+	{
+		.name = "pull-down",
+		.mask = GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN,
+	},
+	{
+		.name = "bias-disabled",
+		.mask = GPIO_V2_LINE_FLAG_BIAS_DISABLED,
+	},
+	{
+		.name = "clock-realtime",
+		.mask = GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME,
+	},
+};
+
+static void print_attributes(struct gpio_v2_line_info *info)
+{
+	int i;
+	const char *field_format = "%s";
+
+	for (i = 0; i < ARRAY_SIZE(flagnames); i++) {
+		if (info->flags & flagnames[i].mask) {
+			fprintf(stdout, field_format, flagnames[i].name);
+			field_format = ", %s";
+		}
+	}
+
+	if ((info->flags & GPIO_V2_LINE_FLAG_EDGE_RISING) &&
+	    (info->flags & GPIO_V2_LINE_FLAG_EDGE_FALLING))
+		fprintf(stdout, field_format, "both-edges");
+	else if (info->flags & GPIO_V2_LINE_FLAG_EDGE_RISING)
+		fprintf(stdout, field_format, "rising-edge");
+	else if (info->flags & GPIO_V2_LINE_FLAG_EDGE_FALLING)
+		fprintf(stdout, field_format, "falling-edge");
+
+	for (i = 0; i < info->num_attrs; i++) {
+		if (info->attrs[i].id == GPIO_V2_LINE_ATTR_ID_DEBOUNCE)
+			fprintf(stdout, ", debounce_period=%dusec",
+				info->attrs[i].debounce_period_us);
+	}
+}
+
+int list_device(const char *device_name)
+{
+	struct gpiochip_info cinfo;
+	char *chrdev_name;
+	int fd;
+	int ret;
+	int i;
+
+	ret = asprintf(&chrdev_name, "/dev/%s", device_name);
+	if (ret < 0)
+		return -ENOMEM;
+
+	fd = open(chrdev_name, 0);
+	if (fd == -1) {
+		ret = -errno;
+		fprintf(stderr, "Failed to open %s\n", chrdev_name);
+		goto exit_free_name;
+	}
+
+	/* Inspect this GPIO chip */
+	ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &cinfo);
+	if (ret == -1) {
+		ret = -errno;
+		perror("Failed to issue CHIPINFO IOCTL\n");
+		goto exit_close_error;
+	}
+	fprintf(stdout, "GPIO chip: %s, \"%s\", %u GPIO lines\n",
+		cinfo.name, cinfo.label, cinfo.lines);
+
+	/* Loop over the lines and print info */
+	for (i = 0; i < cinfo.lines; i++) {
+		struct gpio_v2_line_info linfo;
+
+		memset(&linfo, 0, sizeof(linfo));
+		linfo.offset = i;
+
+		ret = ioctl(fd, GPIO_V2_GET_LINEINFO_IOCTL, &linfo);
+		if (ret == -1) {
+			ret = -errno;
+			perror("Failed to issue LINEINFO IOCTL\n");
+			goto exit_close_error;
+		}
+		fprintf(stdout, "\tline %2d:", linfo.offset);
+		if (linfo.name[0])
+			fprintf(stdout, " \"%s\"", linfo.name);
+		else
+			fprintf(stdout, " unnamed");
+		if (linfo.consumer[0])
+			fprintf(stdout, " \"%s\"", linfo.consumer);
+		else
+			fprintf(stdout, " unused");
+		if (linfo.flags) {
+			fprintf(stdout, " [");
+			print_attributes(&linfo);
+			fprintf(stdout, "]");
+		}
+		fprintf(stdout, "\n");
+
+	}
+
+exit_close_error:
+	if (close(fd) == -1)
+		perror("Failed to close GPIO character device file");
+exit_free_name:
+	free(chrdev_name);
+	return ret;
+}
+
+void print_usage(void)
+{
+	fprintf(stderr, "Usage: lsgpio [options]...\n"
+		"List GPIO chips, lines and states\n"
+		"  -n <name>  List GPIOs on a named device\n"
+		"  -?         This helptext\n"
+	);
+}
+
+int main(int argc, char **argv)
+{
+	const char *device_name = NULL;
+	int ret;
+	int c;
+
+	while ((c = getopt(argc, argv, "n:")) != -1) {
+		switch (c) {
+		case 'n':
+			device_name = optarg;
+			break;
+		case '?':
+			print_usage();
+			return -1;
+		}
+	}
+
+	if (device_name)
+		ret = list_device(device_name);
+	else {
+		const struct dirent *ent;
+		DIR *dp;
+
+		/* List all GPIO devices one at a time */
+		dp = opendir("/dev");
+		if (!dp) {
+			ret = -errno;
+			goto error_out;
+		}
+
+		ret = -ENOENT;
+		while (ent = readdir(dp), ent) {
+			if (check_prefix(ent->d_name, "gpiochip")) {
+				ret = list_device(ent->d_name);
+				if (ret)
+					break;
+			}
+		}
+
+		ret = 0;
+		if (closedir(dp) == -1) {
+			perror("scanning devices: Failed to close directory");
+			ret = -errno;
+		}
+	}
+error_out:
+	return ret;
+}