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, 187 insertions, 0 deletions

diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
new file mode 100644
index 000000000..e711ac1d4
--- /dev/null
+++ b/drivers/pci/remove.c
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/pci.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+
+#include "pci.h"
+
+static void pci_free_resources(struct pci_dev *dev)
+{
+	struct resource *res;
+
+	pci_dev_for_each_resource(dev, res) {
+		if (res->parent)
+			release_resource(res);
+	}
+}
+
+static void pci_stop_dev(struct pci_dev *dev)
+{
+	pci_pme_active(dev, false);
+
+	if (!pci_dev_test_and_clear_added(dev))
+		return;
+
+	device_release_driver(&dev->dev);
+	pci_proc_detach_device(dev);
+	of_pci_remove_node(dev);
+}
+
+static void pci_destroy_dev(struct pci_dev *dev)
+{
+	if (pci_dev_test_and_set_removed(dev))
+		return;
+
+	platform_pci_remove_wake(dev);
+	pci_doe_sysfs_teardown(dev);
+	pci_npem_remove(dev);
+
+	/*
+	 * While device is in D0 drop the device from TSM link operations
+	 * including unbind and disconnect (IDE + SPDM teardown).
+	 */
+	pci_tsm_destroy(dev);
+
+	device_del(&dev->dev);
+
+	down_write(&pci_bus_sem);
+	list_del(&dev->bus_list);
+	up_write(&pci_bus_sem);
+
+	pci_doe_destroy(dev);
+	pci_ide_destroy(dev);
+	pcie_aspm_exit_link_state(dev);
+	pci_bridge_d3_update(dev);
+	pci_free_resources(dev);
+	put_device(&dev->dev);
+}
+
+void pci_remove_bus(struct pci_bus *bus)
+{
+	pci_proc_detach_bus(bus);
+
+	down_write(&pci_bus_sem);
+	list_del(&bus->node);
+	pci_bus_release_busn_res(bus);
+	up_write(&pci_bus_sem);
+	if (bus->ops->remove_bus)
+		bus->ops->remove_bus(bus);
+
+	pcibios_remove_bus(bus);
+	device_unregister(&bus->dev);
+}
+EXPORT_SYMBOL(pci_remove_bus);
+
+static void pci_stop_bus_device(struct pci_dev *dev)
+{
+	struct pci_bus *bus = dev->subordinate;
+	struct pci_dev *child, *tmp;
+
+	/*
+	 * Stopping an SR-IOV PF device removes all the associated VFs,
+	 * which will update the bus->devices list and confuse the
+	 * iterator.  Therefore, iterate in reverse so we remove the VFs
+	 * first, then the PF.
+	 */
+	if (bus) {
+		list_for_each_entry_safe_reverse(child, tmp,
+						 &bus->devices, bus_list)
+			pci_stop_bus_device(child);
+	}
+
+	pci_stop_dev(dev);
+}
+
+static void pci_remove_bus_device(struct pci_dev *dev)
+{
+	struct pci_bus *bus = dev->subordinate;
+	struct pci_dev *child, *tmp;
+
+	if (bus) {
+		list_for_each_entry_safe(child, tmp,
+					 &bus->devices, bus_list)
+			pci_remove_bus_device(child);
+
+		pci_remove_bus(bus);
+		dev->subordinate = NULL;
+	}
+
+	pci_destroy_dev(dev);
+}
+
+/**
+ * pci_stop_and_remove_bus_device - remove a PCI device and any children
+ * @dev: the device to remove
+ *
+ * Remove a PCI device from the device lists, informing the drivers
+ * that the device has been removed.  We also remove any subordinate
+ * buses and children in a depth-first manner.
+ *
+ * For each device we remove, delete the device structure from the
+ * device lists, remove the /proc entry, and notify userspace
+ * (/sbin/hotplug).
+ */
+void pci_stop_and_remove_bus_device(struct pci_dev *dev)
+{
+	lockdep_assert_held(&pci_rescan_remove_lock);
+	pci_stop_bus_device(dev);
+	pci_remove_bus_device(dev);
+}
+EXPORT_SYMBOL(pci_stop_and_remove_bus_device);
+
+void pci_stop_and_remove_bus_device_locked(struct pci_dev *dev)
+{
+	pci_lock_rescan_remove();
+	pci_stop_and_remove_bus_device(dev);
+	pci_unlock_rescan_remove();
+}
+EXPORT_SYMBOL_GPL(pci_stop_and_remove_bus_device_locked);
+
+void pci_stop_root_bus(struct pci_bus *bus)
+{
+	struct pci_dev *child, *tmp;
+	struct pci_host_bridge *host_bridge;
+
+	if (!pci_is_root_bus(bus))
+		return;
+
+	host_bridge = to_pci_host_bridge(bus->bridge);
+	list_for_each_entry_safe_reverse(child, tmp,
+					 &bus->devices, bus_list)
+		pci_stop_bus_device(child);
+
+	of_pci_remove_host_bridge_node(host_bridge);
+
+	/* stop the host bridge */
+	device_release_driver(&host_bridge->dev);
+}
+EXPORT_SYMBOL_GPL(pci_stop_root_bus);
+
+void pci_remove_root_bus(struct pci_bus *bus)
+{
+	struct pci_dev *child, *tmp;
+	struct pci_host_bridge *host_bridge;
+
+	if (!pci_is_root_bus(bus))
+		return;
+
+	host_bridge = to_pci_host_bridge(bus->bridge);
+	list_for_each_entry_safe(child, tmp,
+				 &bus->devices, bus_list)
+		pci_remove_bus_device(child);
+
+#ifdef CONFIG_PCI_DOMAINS_GENERIC
+	/* Release domain_nr if it was dynamically allocated */
+	if (host_bridge->domain_nr == PCI_DOMAIN_NR_NOT_SET)
+		pci_bus_release_domain_nr(host_bridge->dev.parent, bus->domain_nr);
+#endif
+
+	pci_remove_bus(bus);
+	host_bridge->bus = NULL;
+
+	/* remove the host bridge */
+	device_del(&host_bridge->dev);
+}
+EXPORT_SYMBOL_GPL(pci_remove_root_bus);