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, 98 insertions, 0 deletions

diff --git a/drivers/vfio/pci/trace.h b/drivers/vfio/pci/trace.h
new file mode 100644
index 000000000..b2aa986ab
--- /dev/null
+++ b/drivers/vfio/pci/trace.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * VFIO PCI mmap/mmap_fault tracepoints
+ *
+ * Copyright (C) 2018 IBM Corp.  All rights reserved.
+ *     Author: Alexey Kardashevskiy <aik@ozlabs.ru>
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM vfio_pci
+
+#if !defined(_TRACE_VFIO_PCI_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_VFIO_PCI_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(vfio_pci_nvgpu_mmap_fault,
+	TP_PROTO(struct pci_dev *pdev, unsigned long hpa, unsigned long ua,
+			vm_fault_t ret),
+	TP_ARGS(pdev, hpa, ua, ret),
+
+	TP_STRUCT__entry(
+		__field(const char *, name)
+		__field(unsigned long, hpa)
+		__field(unsigned long, ua)
+		__field(int, ret)
+	),
+
+	TP_fast_assign(
+		__entry->name = dev_name(&pdev->dev),
+		__entry->hpa = hpa;
+		__entry->ua = ua;
+		__entry->ret = ret;
+	),
+
+	TP_printk("%s: %lx -> %lx ret=%d", __entry->name, __entry->hpa,
+			__entry->ua, __entry->ret)
+);
+
+TRACE_EVENT(vfio_pci_nvgpu_mmap,
+	TP_PROTO(struct pci_dev *pdev, unsigned long hpa, unsigned long ua,
+			unsigned long size, int ret),
+	TP_ARGS(pdev, hpa, ua, size, ret),
+
+	TP_STRUCT__entry(
+		__field(const char *, name)
+		__field(unsigned long, hpa)
+		__field(unsigned long, ua)
+		__field(unsigned long, size)
+		__field(int, ret)
+	),
+
+	TP_fast_assign(
+		__entry->name = dev_name(&pdev->dev),
+		__entry->hpa = hpa;
+		__entry->ua = ua;
+		__entry->size = size;
+		__entry->ret = ret;
+	),
+
+	TP_printk("%s: %lx -> %lx size=%lx ret=%d", __entry->name, __entry->hpa,
+			__entry->ua, __entry->size, __entry->ret)
+);
+
+TRACE_EVENT(vfio_pci_npu2_mmap,
+	TP_PROTO(struct pci_dev *pdev, unsigned long hpa, unsigned long ua,
+			unsigned long size, int ret),
+	TP_ARGS(pdev, hpa, ua, size, ret),
+
+	TP_STRUCT__entry(
+		__field(const char *, name)
+		__field(unsigned long, hpa)
+		__field(unsigned long, ua)
+		__field(unsigned long, size)
+		__field(int, ret)
+	),
+
+	TP_fast_assign(
+		__entry->name = dev_name(&pdev->dev),
+		__entry->hpa = hpa;
+		__entry->ua = ua;
+		__entry->size = size;
+		__entry->ret = ret;
+	),
+
+	TP_printk("%s: %lx -> %lx size=%lx ret=%d", __entry->name, __entry->hpa,
+			__entry->ua, __entry->size, __entry->ret)
+);
+
+#endif /* _TRACE_VFIO_PCI_H */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH ../../drivers/vfio/pci
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>