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, 295 insertions, 0 deletions

diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
new file mode 100644
index 000000000..d77403d88
--- /dev/null
+++ b/drivers/pci/pcie/err.c
@@ -0,0 +1,295 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file implements the error recovery as a core part of PCIe error
+ * reporting. When a PCIe error is delivered, an error message will be
+ * collected and printed to console, then, an error recovery procedure
+ * will be executed by following the PCI error recovery rules.
+ *
+ * Copyright (C) 2006 Intel Corp.
+ *	Tom Long Nguyen (tom.l.nguyen@intel.com)
+ *	Zhang Yanmin (yanmin.zhang@intel.com)
+ */
+
+#define dev_fmt(fmt) "AER: " fmt
+
+#include <linux/pci.h>
+#include <linux/pm_runtime.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/aer.h>
+#include "portdrv.h"
+#include "../pci.h"
+
+static pci_ers_result_t merge_result(enum pci_ers_result orig,
+				  enum pci_ers_result new)
+{
+	if (new == PCI_ERS_RESULT_NO_AER_DRIVER)
+		return PCI_ERS_RESULT_NO_AER_DRIVER;
+
+	if (new == PCI_ERS_RESULT_NONE)
+		return orig;
+
+	switch (orig) {
+	case PCI_ERS_RESULT_CAN_RECOVER:
+	case PCI_ERS_RESULT_RECOVERED:
+		orig = new;
+		break;
+	case PCI_ERS_RESULT_DISCONNECT:
+		if (new == PCI_ERS_RESULT_NEED_RESET)
+			orig = PCI_ERS_RESULT_NEED_RESET;
+		break;
+	default:
+		break;
+	}
+
+	return orig;
+}
+
+static int report_error_detected(struct pci_dev *dev,
+				 pci_channel_state_t state,
+				 enum pci_ers_result *result)
+{
+	struct pci_driver *pdrv;
+	pci_ers_result_t vote;
+	const struct pci_error_handlers *err_handler;
+
+	device_lock(&dev->dev);
+	pdrv = dev->driver;
+	if (pci_dev_is_disconnected(dev)) {
+		vote = PCI_ERS_RESULT_DISCONNECT;
+	} else if (!pci_dev_set_io_state(dev, state)) {
+		pci_info(dev, "can't recover (state transition %u -> %u invalid)\n",
+			dev->error_state, state);
+		vote = PCI_ERS_RESULT_NONE;
+	} else if (!pdrv || !pdrv->err_handler ||
+		   !pdrv->err_handler->error_detected) {
+		/*
+		 * If any device in the subtree does not have an error_detected
+		 * callback, PCI_ERS_RESULT_NO_AER_DRIVER prevents subsequent
+		 * error callbacks of "any" device in the subtree, and will
+		 * exit in the disconnected error state.
+		 */
+		if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
+			vote = PCI_ERS_RESULT_NO_AER_DRIVER;
+			pci_info(dev, "can't recover (no error_detected callback)\n");
+		} else {
+			vote = PCI_ERS_RESULT_NONE;
+		}
+	} else {
+		err_handler = pdrv->err_handler;
+		vote = err_handler->error_detected(dev, state);
+	}
+	pci_uevent_ers(dev, vote);
+	*result = merge_result(*result, vote);
+	device_unlock(&dev->dev);
+	return 0;
+}
+
+static int pci_pm_runtime_get_sync(struct pci_dev *pdev, void *data)
+{
+	pm_runtime_get_sync(&pdev->dev);
+	return 0;
+}
+
+static int pci_pm_runtime_put(struct pci_dev *pdev, void *data)
+{
+	pm_runtime_put(&pdev->dev);
+	return 0;
+}
+
+static int report_frozen_detected(struct pci_dev *dev, void *data)
+{
+	return report_error_detected(dev, pci_channel_io_frozen, data);
+}
+
+static int report_normal_detected(struct pci_dev *dev, void *data)
+{
+	return report_error_detected(dev, pci_channel_io_normal, data);
+}
+
+static int report_perm_failure_detected(struct pci_dev *dev, void *data)
+{
+	struct pci_driver *pdrv;
+	const struct pci_error_handlers *err_handler;
+
+	device_lock(&dev->dev);
+	pdrv = dev->driver;
+	if (!pdrv || !pdrv->err_handler || !pdrv->err_handler->error_detected)
+		goto out;
+
+	err_handler = pdrv->err_handler;
+	err_handler->error_detected(dev, pci_channel_io_perm_failure);
+out:
+	pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
+	device_unlock(&dev->dev);
+	return 0;
+}
+
+static int report_mmio_enabled(struct pci_dev *dev, void *data)
+{
+	struct pci_driver *pdrv;
+	pci_ers_result_t vote, *result = data;
+	const struct pci_error_handlers *err_handler;
+
+	device_lock(&dev->dev);
+	pdrv = dev->driver;
+	if (!pdrv || !pdrv->err_handler || !pdrv->err_handler->mmio_enabled)
+		goto out;
+
+	err_handler = pdrv->err_handler;
+	vote = err_handler->mmio_enabled(dev);
+	*result = merge_result(*result, vote);
+out:
+	device_unlock(&dev->dev);
+	return 0;
+}
+
+static int report_slot_reset(struct pci_dev *dev, void *data)
+{
+	struct pci_driver *pdrv;
+	pci_ers_result_t vote, *result = data;
+	const struct pci_error_handlers *err_handler;
+
+	device_lock(&dev->dev);
+	pdrv = dev->driver;
+	if (!pci_dev_set_io_state(dev, pci_channel_io_normal) ||
+	    !pdrv || !pdrv->err_handler || !pdrv->err_handler->slot_reset)
+		goto out;
+
+	err_handler = pdrv->err_handler;
+	vote = err_handler->slot_reset(dev);
+	*result = merge_result(*result, vote);
+out:
+	device_unlock(&dev->dev);
+	return 0;
+}
+
+static int report_resume(struct pci_dev *dev, void *data)
+{
+	struct pci_driver *pdrv;
+	const struct pci_error_handlers *err_handler;
+
+	device_lock(&dev->dev);
+	pdrv = dev->driver;
+	if (!pci_dev_set_io_state(dev, pci_channel_io_normal) ||
+	    !pdrv || !pdrv->err_handler || !pdrv->err_handler->resume)
+		goto out;
+
+	err_handler = pdrv->err_handler;
+	err_handler->resume(dev);
+out:
+	pci_uevent_ers(dev, PCI_ERS_RESULT_RECOVERED);
+	device_unlock(&dev->dev);
+	return 0;
+}
+
+/**
+ * pci_walk_bridge - walk bridges potentially AER affected
+ * @bridge:	bridge which may be a Port, an RCEC, or an RCiEP
+ * @cb:		callback to be called for each device found
+ * @userdata:	arbitrary pointer to be passed to callback
+ *
+ * If the device provided is a bridge, walk the subordinate bus, including
+ * any bridged devices on buses under this bus.  Call the provided callback
+ * on each device found.
+ *
+ * If the device provided has no subordinate bus, e.g., an RCEC or RCiEP,
+ * call the callback on the device itself.
+ */
+static void pci_walk_bridge(struct pci_dev *bridge,
+			    int (*cb)(struct pci_dev *, void *),
+			    void *userdata)
+{
+	if (bridge->subordinate)
+		pci_walk_bus(bridge->subordinate, cb, userdata);
+	else
+		cb(bridge, userdata);
+}
+
+pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
+		pci_channel_state_t state,
+		pci_ers_result_t (*reset_subordinates)(struct pci_dev *pdev))
+{
+	int type = pci_pcie_type(dev);
+	struct pci_dev *bridge;
+	pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
+	struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
+
+	/*
+	 * If the error was detected by a Root Port, Downstream Port, RCEC,
+	 * or RCiEP, recovery runs on the device itself.  For Ports, that
+	 * also includes any subordinate devices.
+	 *
+	 * If it was detected by another device (Endpoint, etc), recovery
+	 * runs on the device and anything else under the same Port, i.e.,
+	 * everything under "bridge".
+	 */
+	if (type == PCI_EXP_TYPE_ROOT_PORT ||
+	    type == PCI_EXP_TYPE_DOWNSTREAM ||
+	    type == PCI_EXP_TYPE_RC_EC ||
+	    type == PCI_EXP_TYPE_RC_END)
+		bridge = dev;
+	else
+		bridge = pci_upstream_bridge(dev);
+
+	pci_walk_bridge(bridge, pci_pm_runtime_get_sync, NULL);
+
+	pci_dbg(bridge, "broadcast error_detected message\n");
+	if (state == pci_channel_io_frozen)
+		pci_walk_bridge(bridge, report_frozen_detected, &status);
+	else
+		pci_walk_bridge(bridge, report_normal_detected, &status);
+
+	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
+		status = PCI_ERS_RESULT_RECOVERED;
+		pci_dbg(bridge, "broadcast mmio_enabled message\n");
+		pci_walk_bridge(bridge, report_mmio_enabled, &status);
+	}
+
+	if (status == PCI_ERS_RESULT_NEED_RESET ||
+	    state == pci_channel_io_frozen) {
+		if (reset_subordinates(bridge) != PCI_ERS_RESULT_RECOVERED) {
+			pci_warn(bridge, "subordinate device reset failed\n");
+			goto failed;
+		}
+	}
+
+	if (status == PCI_ERS_RESULT_NEED_RESET) {
+		status = PCI_ERS_RESULT_RECOVERED;
+		pci_dbg(bridge, "broadcast slot_reset message\n");
+		pci_walk_bridge(bridge, report_slot_reset, &status);
+	}
+
+	if (status != PCI_ERS_RESULT_RECOVERED)
+		goto failed;
+
+	pci_dbg(bridge, "broadcast resume message\n");
+	pci_walk_bridge(bridge, report_resume, &status);
+
+	/*
+	 * If we have native control of AER, clear error status in the device
+	 * that detected the error.  If the platform retained control of AER,
+	 * it is responsible for clearing this status.  In that case, the
+	 * signaling device may not even be visible to the OS.
+	 */
+	if (host->native_aer || pcie_ports_native) {
+		pcie_clear_device_status(dev);
+		pci_aer_clear_nonfatal_status(dev);
+	}
+
+	pci_walk_bridge(bridge, pci_pm_runtime_put, NULL);
+
+	pci_info(bridge, "device recovery successful\n");
+	return status;
+
+failed:
+	pci_walk_bridge(bridge, pci_pm_runtime_put, NULL);
+
+	pci_walk_bridge(bridge, report_perm_failure_detected, NULL);
+
+	pci_info(bridge, "device recovery failed\n");
+
+	return status;
+}
+EXPORT_SYMBOL_GPL(pcie_do_recovery);