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, 140 insertions, 0 deletions

diff --git a/drivers/parisc/wax.c b/drivers/parisc/wax.c
new file mode 100644
index 000000000..a82a5e88e
--- /dev/null
+++ b/drivers/parisc/wax.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	WAX Device Driver
+ *
+ *	(c) Copyright 2000 The Puffin Group Inc.
+ *
+ *	(c) 2000-2023 by Helge Deller <deller@gmx.de>
+ */
+
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#include <asm/io.h>
+#include <asm/hardware.h>
+
+#include "gsc.h"
+
+#define WAX_GSC_IRQ	7	/* Hardcoded Interrupt for GSC */
+
+static void wax_choose_irq(struct parisc_device *dev, void *ctrl)
+{
+	int irq;
+
+	switch (dev->id.sversion) {
+		case 0x73:	irq =  1; break; /* i8042 General */
+		case 0x8c:	irq =  6; break; /* Serial */
+		case 0x90:	irq = 10; break; /* EISA */
+		default:	return;		 /* Unknown */
+	}
+
+	gsc_asic_assign_irq(ctrl, irq, &dev->irq);
+
+	switch (dev->id.sversion) {
+		case 0x73:	irq =  2; break; /* i8042 High-priority */
+		case 0x90:	irq =  0; break; /* EISA NMI */
+		default:	return;		 /* No secondary IRQ */
+	}
+
+	gsc_asic_assign_irq(ctrl, irq, &dev->aux_irq);
+}
+
+static void __init
+wax_init_irq(struct gsc_asic *wax)
+{
+	unsigned long base = wax->hpa;
+
+	/* Wax-off */
+	gsc_writel(0x00000000, base+OFFSET_IMR);
+
+	/* clear pending interrupts */
+	gsc_readl(base+OFFSET_IRR);
+
+	/* We're not really convinced we want to reset the onboard
+         * devices. Firmware does it for us...
+	 */
+
+	/* Resets */
+//	gsc_writel(0xFFFFFFFF, base+0x1000); /* HIL */
+//	gsc_writel(0xFFFFFFFF, base+0x2000); /* RS232-B on Wax */
+}
+
+static int __init wax_init_chip(struct parisc_device *dev)
+{
+	struct gsc_asic *wax;
+	struct parisc_device *parent;
+	int ret;
+
+	wax = kzalloc_obj(*wax);
+	if (!wax)
+		return -ENOMEM;
+
+	wax->name = "wax";
+	wax->hpa = dev->hpa.start;
+
+	wax->version = 0;   /* gsc_readb(wax->hpa+WAX_VER); */
+	printk(KERN_INFO "%s at 0x%lx found.\n", wax->name, wax->hpa);
+
+	/* Stop wax hissing for a bit */
+	wax_init_irq(wax);
+
+	/* the IRQ wax should use */
+	dev->irq = gsc_claim_irq(&wax->gsc_irq, WAX_GSC_IRQ);
+	if (dev->irq < 0) {
+		printk(KERN_ERR "%s(): cannot get GSC irq\n",
+				__func__);
+		kfree(wax);
+		return -EBUSY;
+	}
+
+	wax->eim = ((u32) wax->gsc_irq.txn_addr) | wax->gsc_irq.txn_data;
+
+	ret = request_irq(wax->gsc_irq.irq, gsc_asic_intr, 0, "wax", wax);
+	if (ret < 0) {
+		kfree(wax);
+		return ret;
+	}
+
+	/* enable IRQ's for devices below WAX */
+	gsc_writel(wax->eim, wax->hpa + OFFSET_IAR);
+
+	/* Done init'ing, register this driver */
+	ret = gsc_common_setup(dev, wax);
+	if (ret) {
+		kfree(wax);
+		return ret;
+	}
+
+	gsc_fixup_irqs(dev, wax, wax_choose_irq);
+	/* On 715-class machines, Wax EISA is a sibling of Wax, not a child. */
+	parent = parisc_parent(dev);
+	if (parent->id.hw_type != HPHW_IOA) {
+		gsc_fixup_irqs(parent, wax, wax_choose_irq);
+	}
+
+	return ret;
+}
+
+static const struct parisc_device_id wax_tbl[] __initconst = {
+	{ HPHW_BA, HVERSION_REV_ANY_ID, HVERSION_ANY_ID, 0x0008e },
+	{ 0, }
+};
+
+MODULE_DEVICE_TABLE(parisc, wax_tbl);
+
+static struct parisc_driver wax_driver __refdata = {
+	.name =		"wax",
+	.id_table =	wax_tbl,
+	.probe =	wax_init_chip,
+};
+
+static int __init wax_init(void)
+{
+	return register_parisc_driver(&wax_driver);
+}
+arch_initcall(wax_init);