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, 277 insertions, 0 deletions

diff --git a/sound/ppc/daca.c b/sound/ppc/daca.c
new file mode 100644
index 000000000..f35cb870d
--- /dev/null
+++ b/sound/ppc/daca.c
@@ -0,0 +1,277 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PMac DACA lowlevel functions
+ *
+ * Copyright (c) by Takashi Iwai <tiwai@suse.de>
+ */
+
+
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/kmod.h>
+#include <linux/slab.h>
+#include <sound/core.h>
+#include "pmac.h"
+
+/* i2c address */
+#define DACA_I2C_ADDR	0x4d
+
+/* registers */
+#define DACA_REG_SR	0x01
+#define DACA_REG_AVOL	0x02
+#define DACA_REG_GCFG	0x03
+
+/* maximum volume value */
+#define DACA_VOL_MAX	0x38
+
+
+struct pmac_daca {
+	struct pmac_keywest i2c;
+	int left_vol, right_vol;
+	unsigned int deemphasis : 1;
+	unsigned int amp_on : 1;
+};
+
+
+/*
+ * initialize / detect DACA
+ */
+static int daca_init_client(struct pmac_keywest *i2c)
+{
+	unsigned short wdata = 0x00;
+	/* SR: no swap, 1bit delay, 32-48kHz */
+	/* GCFG: power amp inverted, DAC on */
+	if (i2c_smbus_write_byte_data(i2c->client, DACA_REG_SR, 0x08) < 0 ||
+	    i2c_smbus_write_byte_data(i2c->client, DACA_REG_GCFG, 0x05) < 0)
+		return -EINVAL;
+	return i2c_smbus_write_block_data(i2c->client, DACA_REG_AVOL,
+					  2, (unsigned char*)&wdata);
+}
+
+/*
+ * update volume
+ */
+static int daca_set_volume(struct pmac_daca *mix)
+{
+	unsigned char data[2];
+  
+	if (! mix->i2c.client)
+		return -ENODEV;
+  
+	if (mix->left_vol > DACA_VOL_MAX)
+		data[0] = DACA_VOL_MAX;
+	else
+		data[0] = mix->left_vol;
+	if (mix->right_vol > DACA_VOL_MAX)
+		data[1] = DACA_VOL_MAX;
+	else
+		data[1] = mix->right_vol;
+	data[1] |= mix->deemphasis ? 0x40 : 0;
+	if (i2c_smbus_write_block_data(mix->i2c.client, DACA_REG_AVOL,
+				       2, data) < 0) {
+		dev_err(&mix->i2c.client->dev, "failed to set volume\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+
+/* deemphasis switch */
+#define daca_info_deemphasis		snd_ctl_boolean_mono_info
+
+static int daca_get_deemphasis(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	ucontrol->value.integer.value[0] = mix->deemphasis ? 1 : 0;
+	return 0;
+}
+
+static int daca_put_deemphasis(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	int change;
+
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	change = mix->deemphasis != ucontrol->value.integer.value[0];
+	if (change) {
+		mix->deemphasis = !!ucontrol->value.integer.value[0];
+		daca_set_volume(mix);
+	}
+	return change;
+}
+
+/* output volume */
+static int daca_info_volume(struct snd_kcontrol *kcontrol,
+			    struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 2;
+	uinfo->value.integer.min = 0;
+	uinfo->value.integer.max = DACA_VOL_MAX;
+	return 0;
+}
+
+static int daca_get_volume(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	ucontrol->value.integer.value[0] = mix->left_vol;
+	ucontrol->value.integer.value[1] = mix->right_vol;
+	return 0;
+}
+
+static int daca_put_volume(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	unsigned int vol[2];
+	int change;
+
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	vol[0] = ucontrol->value.integer.value[0];
+	vol[1] = ucontrol->value.integer.value[1];
+	if (vol[0] > DACA_VOL_MAX || vol[1] > DACA_VOL_MAX)
+		return -EINVAL;
+	change = mix->left_vol != vol[0] ||
+		mix->right_vol != vol[1];
+	if (change) {
+		mix->left_vol = vol[0];
+		mix->right_vol = vol[1];
+		daca_set_volume(mix);
+	}
+	return change;
+}
+
+/* amplifier switch */
+#define daca_info_amp	daca_info_deemphasis
+
+static int daca_get_amp(struct snd_kcontrol *kcontrol,
+			struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	ucontrol->value.integer.value[0] = mix->amp_on ? 1 : 0;
+	return 0;
+}
+
+static int daca_put_amp(struct snd_kcontrol *kcontrol,
+			struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	int change;
+
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	change = mix->amp_on != ucontrol->value.integer.value[0];
+	if (change) {
+		mix->amp_on = !!ucontrol->value.integer.value[0];
+		i2c_smbus_write_byte_data(mix->i2c.client, DACA_REG_GCFG,
+					  mix->amp_on ? 0x05 : 0x04);
+	}
+	return change;
+}
+
+static const struct snd_kcontrol_new daca_mixers[] = {
+	{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+	  .name = "Deemphasis Switch",
+	  .info = daca_info_deemphasis,
+	  .get = daca_get_deemphasis,
+	  .put = daca_put_deemphasis
+	},
+	{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+	  .name = "Master Playback Volume",
+	  .info = daca_info_volume,
+	  .get = daca_get_volume,
+	  .put = daca_put_volume
+	},
+	{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+	  .name = "Power Amplifier Switch",
+	  .info = daca_info_amp,
+	  .get = daca_get_amp,
+	  .put = daca_put_amp
+	},
+};
+
+
+#ifdef CONFIG_PM
+static void daca_resume(struct snd_pmac *chip)
+{
+	struct pmac_daca *mix = chip->mixer_data;
+	i2c_smbus_write_byte_data(mix->i2c.client, DACA_REG_SR, 0x08);
+	i2c_smbus_write_byte_data(mix->i2c.client, DACA_REG_GCFG,
+				  mix->amp_on ? 0x05 : 0x04);
+	daca_set_volume(mix);
+}
+#endif /* CONFIG_PM */
+
+
+static void daca_cleanup(struct snd_pmac *chip)
+{
+	struct pmac_daca *mix = chip->mixer_data;
+	if (! mix)
+		return;
+	snd_pmac_keywest_cleanup(&mix->i2c);
+	kfree(mix);
+	chip->mixer_data = NULL;
+}
+
+/* exported */
+int snd_pmac_daca_init(struct snd_pmac *chip)
+{
+	int i, err;
+	struct pmac_daca *mix;
+
+	request_module("i2c-powermac");
+
+	mix = kzalloc_obj(*mix);
+	if (! mix)
+		return -ENOMEM;
+	chip->mixer_data = mix;
+	chip->mixer_free = daca_cleanup;
+	mix->amp_on = 1; /* default on */
+
+	mix->i2c.addr = DACA_I2C_ADDR;
+	mix->i2c.init_client = daca_init_client;
+	mix->i2c.name = "DACA";
+	err = snd_pmac_keywest_init(&mix->i2c);
+	if (err < 0)
+		return err;
+
+	/*
+	 * build mixers
+	 */
+	strscpy(chip->card->mixername, "PowerMac DACA");
+
+	for (i = 0; i < ARRAY_SIZE(daca_mixers); i++) {
+		err = snd_ctl_add(chip->card, snd_ctl_new1(&daca_mixers[i], chip));
+		if (err < 0)
+			return err;
+	}
+
+#ifdef CONFIG_PM
+	chip->resume = daca_resume;
+#endif
+
+	return 0;
+}