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, 190 insertions, 0 deletions

diff --git a/sound/ppc/powermac.c b/sound/ppc/powermac.c
new file mode 100644
index 000000000..e685d2458
--- /dev/null
+++ b/sound/ppc/powermac.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for PowerMac AWACS
+ * Copyright (c) 2001 by Takashi Iwai <tiwai@suse.de>
+ *   based on dmasound.c.
+ */
+
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/initval.h>
+#include "pmac.h"
+#include "awacs.h"
+#include "burgundy.h"
+
+#define CHIP_NAME "PMac"
+
+MODULE_DESCRIPTION("PowerMac");
+MODULE_LICENSE("GPL");
+
+static int index = SNDRV_DEFAULT_IDX1;		/* Index 0-MAX */
+static char *id = SNDRV_DEFAULT_STR1;		/* ID for this card */
+static bool enable_beep = 1;
+
+module_param(index, int, 0444);
+MODULE_PARM_DESC(index, "Index value for " CHIP_NAME " soundchip.");
+module_param(id, charp, 0444);
+MODULE_PARM_DESC(id, "ID string for " CHIP_NAME " soundchip.");
+module_param(enable_beep, bool, 0444);
+MODULE_PARM_DESC(enable_beep, "Enable beep using PCM.");
+
+static struct platform_device *device;
+
+
+/*
+ */
+
+static int snd_pmac_probe(struct platform_device *devptr)
+{
+	struct snd_card *card;
+	struct snd_pmac *chip;
+	char *name_ext;
+	int err;
+
+	err = snd_card_new(&devptr->dev, index, id, THIS_MODULE, 0, &card);
+	if (err < 0)
+		return err;
+
+	err = snd_pmac_new(card, &chip);
+	if (err < 0)
+		goto __error;
+	card->private_data = chip;
+
+	switch (chip->model) {
+	case PMAC_BURGUNDY:
+		strscpy(card->driver, "PMac Burgundy");
+		strscpy(card->shortname, "PowerMac Burgundy");
+		sprintf(card->longname, "%s (Dev %d) Sub-frame %d",
+			card->shortname, chip->device_id, chip->subframe);
+		err = snd_pmac_burgundy_init(chip);
+		if (err < 0)
+			goto __error;
+		break;
+	case PMAC_DACA:
+		strscpy(card->driver, "PMac DACA");
+		strscpy(card->shortname, "PowerMac DACA");
+		sprintf(card->longname, "%s (Dev %d) Sub-frame %d",
+			card->shortname, chip->device_id, chip->subframe);
+		err = snd_pmac_daca_init(chip);
+		if (err < 0)
+			goto __error;
+		break;
+	case PMAC_TUMBLER:
+	case PMAC_SNAPPER:
+		name_ext = chip->model == PMAC_TUMBLER ? "Tumbler" : "Snapper";
+		sprintf(card->driver, "PMac %s", name_ext);
+		sprintf(card->shortname, "PowerMac %s", name_ext);
+		sprintf(card->longname, "%s (Dev %d) Sub-frame %d",
+			card->shortname, chip->device_id, chip->subframe);
+		err = snd_pmac_tumbler_init(chip);
+		if (err < 0)
+			goto __error;
+		err = snd_pmac_tumbler_post_init();
+		if (err < 0)
+			goto __error;
+		break;
+	case PMAC_AWACS:
+	case PMAC_SCREAMER:
+		name_ext = chip->model == PMAC_SCREAMER ? "Screamer" : "AWACS";
+		sprintf(card->driver, "PMac %s", name_ext);
+		sprintf(card->shortname, "PowerMac %s", name_ext);
+		if (chip->is_pbook_3400)
+			name_ext = " [PB3400]";
+		else if (chip->is_pbook_G3)
+			name_ext = " [PBG3]";
+		else
+			name_ext = "";
+		sprintf(card->longname, "%s%s Rev %d",
+			card->shortname, name_ext, chip->revision);
+		err = snd_pmac_awacs_init(chip);
+		if (err < 0)
+			goto __error;
+		break;
+	default:
+		dev_err(&devptr->dev, "unsupported hardware %d\n", chip->model);
+		err = -EINVAL;
+		goto __error;
+	}
+
+	err = snd_pmac_pcm_new(chip);
+	if (err < 0)
+		goto __error;
+
+	chip->initialized = 1;
+	if (enable_beep)
+		snd_pmac_attach_beep(chip);
+
+	err = snd_card_register(card);
+	if (err < 0)
+		goto __error;
+
+	platform_set_drvdata(devptr, card);
+	return 0;
+
+__error:
+	snd_card_free(card);
+	return err;
+}
+
+
+static void snd_pmac_remove(struct platform_device *devptr)
+{
+	snd_card_free(platform_get_drvdata(devptr));
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int snd_pmac_driver_suspend(struct device *dev)
+{
+	struct snd_card *card = dev_get_drvdata(dev);
+	snd_pmac_suspend(card->private_data);
+	return 0;
+}
+
+static int snd_pmac_driver_resume(struct device *dev)
+{
+	struct snd_card *card = dev_get_drvdata(dev);
+	snd_pmac_resume(card->private_data);
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(snd_pmac_pm, snd_pmac_driver_suspend, snd_pmac_driver_resume);
+#define SND_PMAC_PM_OPS	&snd_pmac_pm
+#else
+#define SND_PMAC_PM_OPS	NULL
+#endif
+
+#define SND_PMAC_DRIVER		"snd_powermac"
+
+static struct platform_driver snd_pmac_driver = {
+	.probe		= snd_pmac_probe,
+	.remove		= snd_pmac_remove,
+	.driver		= {
+		.name	= SND_PMAC_DRIVER,
+		.pm	= SND_PMAC_PM_OPS,
+	},
+};
+
+static int __init alsa_card_pmac_init(void)
+{
+	int err;
+
+	err = platform_driver_register(&snd_pmac_driver);
+	if (err < 0)
+		return err;
+	device = platform_device_register_simple(SND_PMAC_DRIVER, -1, NULL, 0);
+	return 0;
+
+}
+
+static void __exit alsa_card_pmac_exit(void)
+{
+	if (!IS_ERR(device))
+		platform_device_unregister(device);
+	platform_driver_unregister(&snd_pmac_driver);
+}
+
+module_init(alsa_card_pmac_init)
+module_exit(alsa_card_pmac_exit)