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, 153 insertions, 0 deletions

diff --git a/sound/soc/codecs/ac97.c b/sound/soc/codecs/ac97.c
new file mode 100644
index 000000000..d8444a083
--- /dev/null
+++ b/sound/soc/codecs/ac97.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * ac97.c  --  ALSA Soc AC97 codec support
+ *
+ * Copyright 2005 Wolfson Microelectronics PLC.
+ * Author: Liam Girdwood <lrg@slimlogic.co.uk>
+ *
+ * Generic AC97 support.
+ */
+
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/ac97_codec.h>
+#include <sound/initval.h>
+#include <sound/soc.h>
+
+static const struct snd_soc_dapm_widget ac97_widgets[] = {
+	SND_SOC_DAPM_INPUT("RX"),
+	SND_SOC_DAPM_OUTPUT("TX"),
+};
+
+static const struct snd_soc_dapm_route ac97_routes[] = {
+	{ "AC97 Capture", NULL, "RX" },
+	{ "TX", NULL, "AC97 Playback" },
+};
+
+static int ac97_prepare(struct snd_pcm_substream *substream,
+			struct snd_soc_dai *dai)
+{
+	struct snd_soc_component *component = dai->component;
+	struct snd_ac97 *ac97 = snd_soc_component_get_drvdata(component);
+
+	int reg = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?
+		  AC97_PCM_FRONT_DAC_RATE : AC97_PCM_LR_ADC_RATE;
+	return snd_ac97_set_rate(ac97, reg, substream->runtime->rate);
+}
+
+static const struct snd_soc_dai_ops ac97_dai_ops = {
+	.prepare	= ac97_prepare,
+};
+
+static struct snd_soc_dai_driver ac97_dai = {
+	.name = "ac97-hifi",
+	.playback = {
+		.stream_name = "AC97 Playback",
+		.channels_min = 1,
+		.channels_max = 2,
+		.rates = SNDRV_PCM_RATE_KNOT,
+		.formats = SND_SOC_STD_AC97_FMTS,},
+	.capture = {
+		.stream_name = "AC97 Capture",
+		.channels_min = 1,
+		.channels_max = 2,
+		.rates = SNDRV_PCM_RATE_KNOT,
+		.formats = SND_SOC_STD_AC97_FMTS,},
+	.ops = &ac97_dai_ops,
+};
+
+static int ac97_soc_probe(struct snd_soc_component *component)
+{
+	struct snd_ac97 *ac97;
+	struct snd_ac97_bus *ac97_bus;
+	struct snd_ac97_template ac97_template;
+	int ret;
+
+	/* add codec as bus device for standard ac97 */
+	ret = snd_ac97_bus(component->card->snd_card, 0, soc_ac97_ops,
+			   NULL, &ac97_bus);
+	if (ret < 0)
+		return ret;
+
+	memset(&ac97_template, 0, sizeof(struct snd_ac97_template));
+	ret = snd_ac97_mixer(ac97_bus, &ac97_template, &ac97);
+	if (ret < 0)
+		return ret;
+
+	snd_soc_component_set_drvdata(component, ac97);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int ac97_soc_suspend(struct snd_soc_component *component)
+{
+	struct snd_ac97 *ac97 = snd_soc_component_get_drvdata(component);
+
+	snd_ac97_suspend(ac97);
+
+	return 0;
+}
+
+static int ac97_soc_resume(struct snd_soc_component *component)
+{
+
+	struct snd_ac97 *ac97 = snd_soc_component_get_drvdata(component);
+
+	snd_ac97_resume(ac97);
+
+	return 0;
+}
+#else
+#define ac97_soc_suspend NULL
+#define ac97_soc_resume NULL
+#endif
+
+static const struct snd_soc_component_driver soc_component_dev_ac97 = {
+	.probe			= ac97_soc_probe,
+	.suspend		= ac97_soc_suspend,
+	.resume			= ac97_soc_resume,
+	.dapm_widgets		= ac97_widgets,
+	.num_dapm_widgets	= ARRAY_SIZE(ac97_widgets),
+	.dapm_routes		= ac97_routes,
+	.num_dapm_routes	= ARRAY_SIZE(ac97_routes),
+	.idle_bias_on		= 1,
+	.use_pmdown_time	= 1,
+	.endianness		= 1,
+};
+
+static int ac97_probe(struct platform_device *pdev)
+{
+	return devm_snd_soc_register_component(&pdev->dev,
+			&soc_component_dev_ac97, &ac97_dai, 1);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id ac97_codec_of_match[] = {
+	{ .compatible = "realtek,alc203", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ac97_codec_of_match);
+#endif
+
+static struct platform_driver ac97_codec_driver = {
+	.driver = {
+		.name = "ac97-codec",
+		.of_match_table = of_match_ptr(ac97_codec_of_match),
+	},
+
+	.probe = ac97_probe,
+};
+
+module_platform_driver(ac97_codec_driver);
+
+MODULE_DESCRIPTION("Soc Generic AC97 driver");
+MODULE_AUTHOR("Liam Girdwood");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ac97-codec");