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, 107 insertions, 0 deletions

diff --git a/sound/usb/power.c b/sound/usb/power.c
new file mode 100644
index 000000000..c2d708c87
--- /dev/null
+++ b/sound/usb/power.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *   UAC3 Power Domain state management functions
+ */
+
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include <linux/usb/audio.h>
+#include <linux/usb/audio-v2.h>
+#include <linux/usb/audio-v3.h>
+
+#include "usbaudio.h"
+#include "helper.h"
+#include "power.h"
+
+struct snd_usb_power_domain *
+snd_usb_find_power_domain(struct usb_host_interface *ctrl_iface,
+			  unsigned char id)
+{
+	struct snd_usb_power_domain *pd;
+	void *p;
+
+	pd = kzalloc_obj(*pd);
+	if (!pd)
+		return NULL;
+
+	p = NULL;
+	while ((p = snd_usb_find_csint_desc(ctrl_iface->extra,
+					    ctrl_iface->extralen,
+					    p, UAC3_POWER_DOMAIN)) != NULL) {
+		struct uac3_power_domain_descriptor *pd_desc = p;
+		int i;
+
+		if (!snd_usb_validate_audio_desc(p, UAC_VERSION_3))
+			continue;
+		for (i = 0; i < pd_desc->bNrEntities; i++) {
+			if (pd_desc->baEntityID[i] == id) {
+				pd->pd_id = pd_desc->bPowerDomainID;
+				pd->pd_d1d0_rec =
+					le16_to_cpu(pd_desc->waRecoveryTime1);
+				pd->pd_d2d0_rec =
+					le16_to_cpu(pd_desc->waRecoveryTime2);
+				pd->ctrl_iface = ctrl_iface;
+				return pd;
+			}
+		}
+	}
+
+	kfree(pd);
+	return NULL;
+}
+
+int snd_usb_power_domain_set(struct snd_usb_audio *chip,
+			     struct snd_usb_power_domain *pd,
+			     unsigned char state)
+{
+	struct usb_device *dev = chip->dev;
+	unsigned char current_state;
+	int err, idx;
+
+	idx = snd_usb_ctrl_intf(pd->ctrl_iface) | (pd->pd_id << 8);
+
+	err = snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0),
+			      UAC2_CS_CUR,
+			      USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
+			      UAC3_AC_POWER_DOMAIN_CONTROL << 8, idx,
+			      &current_state, sizeof(current_state));
+	if (err < 0) {
+		dev_err(&dev->dev, "Can't get UAC3 power state for id %d\n",
+			pd->pd_id);
+		return err;
+	}
+
+	if (current_state == state) {
+		dev_dbg(&dev->dev, "UAC3 power domain id %d already in state %d\n",
+			pd->pd_id, state);
+		return 0;
+	}
+
+	err = snd_usb_ctl_msg(chip->dev, usb_sndctrlpipe(chip->dev, 0), UAC2_CS_CUR,
+			      USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,
+			      UAC3_AC_POWER_DOMAIN_CONTROL << 8, idx,
+			      &state, sizeof(state));
+	if (err < 0) {
+		dev_err(&dev->dev, "Can't set UAC3 power state to %d for id %d\n",
+			state, pd->pd_id);
+		return err;
+	}
+
+	if (state == UAC3_PD_STATE_D0) {
+		switch (current_state) {
+		case UAC3_PD_STATE_D2:
+			udelay(pd->pd_d2d0_rec * 50);
+			break;
+		case UAC3_PD_STATE_D1:
+			udelay(pd->pd_d1d0_rec * 50);
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+
+	dev_dbg(&dev->dev, "UAC3 power domain id %d change to state %d\n",
+		pd->pd_id, state);
+
+	return 0;
+}