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, 47 insertions, 0 deletions

diff --git a/drivers/parisc/gsc.h b/drivers/parisc/gsc.h
new file mode 100644
index 000000000..73cbd0bb1
--- /dev/null
+++ b/drivers/parisc/gsc.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * drivers/parisc/gsc.h
+ * Declarations for functions in gsc.c
+ * Copyright (c) 2000-2002 Helge Deller, Matthew Wilcox
+ */
+
+#include <linux/interrupt.h>
+#include <asm/hardware.h>
+#include <asm/parisc-device.h>
+
+#define OFFSET_IRR 0x0000   /* Interrupt request register */
+#define OFFSET_IMR 0x0004   /* Interrupt mask register */
+#define OFFSET_IPR 0x0008   /* Interrupt pending register */
+#define OFFSET_ICR 0x000C   /* Interrupt control register */
+#define OFFSET_IAR 0x0010   /* Interrupt address register */
+
+/* PA I/O Architected devices support at least 5 bits in the EIM register. */
+#define GSC_EIM_WIDTH 5
+
+struct gsc_irq {
+	unsigned long txn_addr;	/* IRQ "target" */
+	int txn_data;		/* HW "IRQ" */
+	int irq;		/* virtual IRQ */
+};
+
+struct gsc_asic {
+	struct parisc_device *gsc;
+	unsigned long hpa;
+	char *name;
+	int version;
+	int type;
+	int eim;
+	struct gsc_irq gsc_irq;
+	int global_irq[32];
+};
+
+int gsc_common_setup(struct parisc_device *parent, struct gsc_asic *gsc_asic);
+int gsc_alloc_irq(struct gsc_irq *dev);			/* dev needs an irq */
+int gsc_claim_irq(struct gsc_irq *dev, int irq);	/* dev needs this irq */
+int gsc_assign_irq(struct irq_chip *type, void *data);
+int gsc_find_local_irq(unsigned int irq, int *global_irq, int limit);
+void gsc_fixup_irqs(struct parisc_device *parent, void *ctrl,
+		void (*choose)(struct parisc_device *child, void *ctrl));
+void gsc_asic_assign_irq(struct gsc_asic *asic, int local_irq, int *irqp);
+
+irqreturn_t gsc_asic_intr(int irq, void *dev);