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, 75 insertions, 0 deletions

diff --git a/drivers/hid/hid-evision.c b/drivers/hid/hid-evision.c
new file mode 100644
index 000000000..3e7f43ab8
--- /dev/null
+++ b/drivers/hid/hid-evision.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for EVision devices
+ *  For now, only ignore bogus consumer reports
+ *  sent after the keyboard has been configured
+ *
+ *  Copyright (c) 2022 Philippe Valembois
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+static int evision_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	/* mapping only applies to USB_DEVICE_ID_EVISION_ICL01 */
+	if (hdev->product != USB_DEVICE_ID_EVISION_ICL01)
+		return 0;
+
+	if ((usage->hid & HID_USAGE_PAGE) != HID_UP_CONSUMER)
+		return 0;
+
+	/* Ignore key down event */
+	if ((usage->hid & HID_USAGE) >> 8 == 0x05)
+		return -1;
+	/* Ignore key up event */
+	if ((usage->hid & HID_USAGE) >> 8 == 0x06)
+		return -1;
+
+	switch (usage->hid & HID_USAGE) {
+	/* Ignore configuration saved event */
+	case 0x0401: return -1;
+	/* Ignore reset event */
+	case 0x0402: return -1;
+	}
+	return 0;
+}
+
+#define REP_DSC_SIZE 236
+#define USAGE_MAX_INDEX 59
+
+static const __u8 *evision_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	if (hdev->product == USB_DEVICE_ID_EV_TELINK_RECEIVER &&
+	    *rsize == REP_DSC_SIZE && rdesc[USAGE_MAX_INDEX] == 0x29 &&
+	    rdesc[USAGE_MAX_INDEX + 1] == 3) {
+		hid_info(hdev, "fixing EVision:TeLink Receiver report descriptor\n");
+		rdesc[USAGE_MAX_INDEX + 1] = 5; // change usage max from 3 to 5
+	}
+	return rdesc;
+}
+
+static const struct hid_device_id evision_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_EVISION, USB_DEVICE_ID_EVISION_ICL01) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_EVISION, USB_DEVICE_ID_EV_TELINK_RECEIVER) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, evision_devices);
+
+static struct hid_driver evision_driver = {
+	.name = "evision",
+	.id_table = evision_devices,
+	.input_mapping = evision_input_mapping,
+	.report_fixup = evision_report_fixup,
+};
+module_hid_driver(evision_driver);
+
+MODULE_DESCRIPTION("HID driver for EVision devices");
+MODULE_LICENSE("GPL");