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, 64 insertions, 0 deletions

diff --git a/drivers/vfio/cdx/private.h b/drivers/vfio/cdx/private.h
new file mode 100644
index 000000000..4c00bf633
--- /dev/null
+++ b/drivers/vfio/cdx/private.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022-2023, Advanced Micro Devices, Inc.
+ */
+
+#ifndef VFIO_CDX_PRIVATE_H
+#define VFIO_CDX_PRIVATE_H
+
+#include <linux/mutex.h>
+
+#define VFIO_CDX_OFFSET_SHIFT    40
+
+static inline u64 vfio_cdx_index_to_offset(u32 index)
+{
+	return ((u64)(index) << VFIO_CDX_OFFSET_SHIFT);
+}
+
+struct vfio_cdx_irq {
+	u32			flags;
+	u32			count;
+	int			irq_no;
+	struct eventfd_ctx	*trigger;
+	char			*name;
+};
+
+struct vfio_cdx_region {
+	u32			flags;
+	u32			type;
+	u64			addr;
+	resource_size_t		size;
+};
+
+struct vfio_cdx_device {
+	struct vfio_device	vdev;
+	struct vfio_cdx_region	*regions;
+	struct mutex		cdx_irqs_lock;
+	struct vfio_cdx_irq	*cdx_irqs;
+	u32			flags;
+#define BME_SUPPORT BIT(0)
+	u32			msi_count;
+};
+
+#ifdef CONFIG_GENERIC_MSI_IRQ
+int vfio_cdx_set_irqs_ioctl(struct vfio_cdx_device *vdev,
+			    u32 flags, unsigned int index,
+			    unsigned int start, unsigned int count,
+			    void *data);
+
+void vfio_cdx_irqs_cleanup(struct vfio_cdx_device *vdev);
+#else
+static int vfio_cdx_set_irqs_ioctl(struct vfio_cdx_device *vdev,
+				   u32 flags, unsigned int index,
+				   unsigned int start, unsigned int count,
+				   void *data)
+{
+	return -EINVAL;
+}
+
+static void vfio_cdx_irqs_cleanup(struct vfio_cdx_device *vdev)
+{
+}
+#endif
+
+#endif /* VFIO_CDX_PRIVATE_H */