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, 105 insertions, 0 deletions

diff --git a/drivers/parisc/hppb.c b/drivers/parisc/hppb.c
new file mode 100644
index 000000000..33709eafe
--- /dev/null
+++ b/drivers/parisc/hppb.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+** hppb.c:
+**      HP-PB bus driver for the NOVA and K-Class systems.
+**
+**      (c) Copyright 2002 Ryan Bradetich
+**      (c) Copyright 2002 Hewlett-Packard Company
+**
+**
+*/
+
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/dma-mapping.h>
+#include <linux/ioport.h>
+
+#include <asm/io.h>
+#include <asm/hardware.h>
+#include <asm/parisc-device.h>
+
+#include "iommu.h"
+
+struct hppb_card {
+	unsigned long hpa;
+	struct resource mmio_region;
+	struct hppb_card *next;
+};
+
+static struct hppb_card hppb_card_head = {
+	.hpa = 0,
+	.next = NULL,
+};
+
+#define IO_IO_LOW  offsetof(struct bc_module, io_io_low)
+#define IO_IO_HIGH offsetof(struct bc_module, io_io_high)
+
+/**
+ * hppb_probe - Determine if the hppb driver should claim this device.
+ * @dev: The device which has been found
+ *
+ * Determine if hppb driver should claim this chip (return 0) or not 
+ * (return 1). If so, initialize the chip and tell other partners in crime 
+ * they have work to do.
+ */
+static int __init hppb_probe(struct parisc_device *dev)
+{
+	int status;
+	struct hppb_card *card = &hppb_card_head;
+
+	while(card->next) {
+		card = card->next;
+	}
+
+	if(card->hpa) {
+		card->next = kzalloc_obj(struct hppb_card);
+		if(!card->next) {
+			printk(KERN_ERR "HP-PB: Unable to allocate memory.\n");
+			return 1;
+		}
+		card = card->next;
+	}
+
+	card->hpa = dev->hpa.start;
+	card->mmio_region.name = "HP-PB Bus";
+	card->mmio_region.flags = IORESOURCE_MEM;
+
+	card->mmio_region.start = gsc_readl(dev->hpa.start + IO_IO_LOW);
+	card->mmio_region.end = gsc_readl(dev->hpa.start + IO_IO_HIGH) - 1;
+
+	status = ccio_request_resource(dev, &card->mmio_region);
+
+	pr_info("Found GeckoBoa at %pap, bus space %pR,%s claimed.\n",
+			&dev->hpa.start,
+			&card->mmio_region,
+			(status < 0) ? " not":"" );
+
+        return 0;
+}
+
+static const struct parisc_device_id hppb_tbl[] __initconst = {
+        { HPHW_BCPORT, HVERSION_REV_ANY_ID, 0x500, 0xc }, /* E25 and K */
+        { HPHW_BCPORT, 0x0, 0x501, 0xc }, /* E35 */
+        { HPHW_BCPORT, 0x0, 0x502, 0xc }, /* E45 */
+        { HPHW_BCPORT, 0x0, 0x503, 0xc }, /* E55 */
+        { 0, }
+};
+
+static struct parisc_driver hppb_driver __refdata = {
+        .name =         "gecko_boa",
+        .id_table =     hppb_tbl,
+	.probe =        hppb_probe,
+};
+
+/**
+ * hppb_init - HP-PB bus initialization procedure.
+ *
+ * Register this driver.
+ */
+static int __init hppb_init(void)
+{
+        return register_parisc_driver(&hppb_driver);
+}
+arch_initcall(hppb_init);