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, 130 insertions, 0 deletions

diff --git a/drivers/ssb/pcihost_wrapper.c b/drivers/ssb/pcihost_wrapper.c
new file mode 100644
index 000000000..5b6b5e0e4
--- /dev/null
+++ b/drivers/ssb/pcihost_wrapper.c
@@ -0,0 +1,130 @@
+/*
+ * Sonics Silicon Backplane
+ * PCI Hostdevice wrapper
+ *
+ * Copyright (c) 2005 Martin Langer <martin-langer@gmx.de>
+ * Copyright (c) 2005 Stefano Brivio <st3@riseup.net>
+ * Copyright (c) 2005 Danny van Dyk <kugelfang@gentoo.org>
+ * Copyright (c) 2005 Andreas Jaggi <andreas.jaggi@waterwave.ch>
+ * Copyright (c) 2005-2007 Michael Buesch <m@bues.ch>
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+
+#include <linux/pm.h>
+#include <linux/pci.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/ssb/ssb.h>
+
+
+#ifdef CONFIG_PM_SLEEP
+static int ssb_pcihost_suspend(struct device *d)
+{
+	struct pci_dev *dev = to_pci_dev(d);
+	struct ssb_bus *ssb = pci_get_drvdata(dev);
+	int err;
+
+	err = ssb_bus_suspend(ssb);
+	if (err)
+		return err;
+	pci_save_state(dev);
+	pci_disable_device(dev);
+
+	/* if there is a wakeup enabled child device on ssb bus,
+	   enable pci wakeup posibility. */
+	device_set_wakeup_enable(d, d->power.wakeup_path);
+
+	pci_prepare_to_sleep(dev);
+
+	return 0;
+}
+
+static int ssb_pcihost_resume(struct device *d)
+{
+	struct pci_dev *dev = to_pci_dev(d);
+	struct ssb_bus *ssb = pci_get_drvdata(dev);
+	int err;
+
+	pci_back_from_sleep(dev);
+	err = pci_enable_device(dev);
+	if (err)
+		return err;
+	pci_restore_state(dev);
+	err = ssb_bus_resume(ssb);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static const struct dev_pm_ops ssb_pcihost_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(ssb_pcihost_suspend, ssb_pcihost_resume)
+};
+
+#endif /* CONFIG_PM_SLEEP */
+
+static int ssb_pcihost_probe(struct pci_dev *dev,
+			     const struct pci_device_id *id)
+{
+	struct ssb_bus *ssb;
+	int err = -ENOMEM;
+	u32 val;
+
+	ssb = kzalloc_obj(*ssb);
+	if (!ssb)
+		goto out;
+	err = pci_enable_device(dev);
+	if (err)
+		goto err_kfree_ssb;
+	err = pci_request_regions(dev, dev_driver_string(&dev->dev));
+	if (err)
+		goto err_pci_disable;
+	pci_set_master(dev);
+
+	/* Disable the RETRY_TIMEOUT register (0x41) to keep
+	 * PCI Tx retries from interfering with C3 CPU state */
+	pci_read_config_dword(dev, 0x40, &val);
+	if ((val & 0x0000ff00) != 0)
+		pci_write_config_dword(dev, 0x40, val & 0xffff00ff);
+
+	err = ssb_bus_pcibus_register(ssb, dev);
+	if (err)
+		goto err_pci_release_regions;
+
+	pci_set_drvdata(dev, ssb);
+
+out:
+	return err;
+
+err_pci_release_regions:
+	pci_release_regions(dev);
+err_pci_disable:
+	pci_disable_device(dev);
+err_kfree_ssb:
+	kfree(ssb);
+	return err;
+}
+
+static void ssb_pcihost_remove(struct pci_dev *dev)
+{
+	struct ssb_bus *ssb = pci_get_drvdata(dev);
+
+	ssb_bus_unregister(ssb);
+	pci_release_regions(dev);
+	pci_disable_device(dev);
+	kfree(ssb);
+	pci_set_drvdata(dev, NULL);
+}
+
+int ssb_pcihost_register(struct pci_driver *driver)
+{
+	driver->probe = ssb_pcihost_probe;
+	driver->remove = ssb_pcihost_remove;
+#ifdef CONFIG_PM_SLEEP
+	driver->driver.pm = &ssb_pcihost_pm_ops;
+#endif
+
+	return pci_register_driver(driver);
+}
+EXPORT_SYMBOL(ssb_pcihost_register);