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, 55 insertions, 0 deletions

diff --git a/drivers/parisc/iommu.h b/drivers/parisc/iommu.h
new file mode 100644
index 000000000..240059cd8
--- /dev/null
+++ b/drivers/parisc/iommu.h
@@ -0,0 +1,55 @@
+#ifndef _IOMMU_H
+#define _IOMMU_H 1
+
+#include <linux/pci.h>
+
+struct parisc_device;
+struct ioc;
+
+static inline struct pci_hba_data *parisc_walk_tree(struct device *dev)
+{
+	struct device *otherdev;
+
+	if (likely(dev->platform_data))
+		return dev->platform_data;
+
+	/* OK, just traverse the bus to find it */
+	for (otherdev = dev->parent;
+	     otherdev;
+	     otherdev = otherdev->parent) {
+		if (otherdev->platform_data) {
+			dev->platform_data = otherdev->platform_data;
+			break;
+		}
+	}
+
+	return dev->platform_data;
+}
+
+static inline struct ioc *GET_IOC(struct device *dev)
+{
+	struct pci_hba_data *pdata = parisc_walk_tree(dev);
+
+	if (!pdata)
+		return NULL;
+	return pdata->iommu;
+}
+
+#ifdef CONFIG_IOMMU_CCIO
+void *ccio_get_iommu(const struct parisc_device *dev);
+int ccio_request_resource(const struct parisc_device *dev,
+		struct resource *res);
+int ccio_allocate_resource(const struct parisc_device *dev,
+		struct resource *res, unsigned long size,
+		unsigned long min, unsigned long max, unsigned long align);
+#else /* !CONFIG_IOMMU_CCIO */
+#define ccio_get_iommu(dev) NULL
+#define ccio_request_resource(dev, res) insert_resource(&iomem_resource, res)
+#define ccio_allocate_resource(dev, res, size, min, max, align) \
+		allocate_resource(&iomem_resource, res, size, min, max, \
+				align, NULL, NULL)
+#endif /* !CONFIG_IOMMU_CCIO */
+
+void *sba_get_iommu(struct parisc_device *dev);
+
+#endif /* _IOMMU_H */