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, 94 insertions, 0 deletions

diff --git a/drivers/hid/hid-xiaomi.c b/drivers/hid/hid-xiaomi.c
new file mode 100644
index 000000000..ef6598550
--- /dev/null
+++ b/drivers/hid/hid-xiaomi.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HID driver for Xiaomi Mi Dual Mode Wireless Mouse Silent Edition
+ *
+ * Copyright (c) 2021 Ilya Skriblovsky
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/hid.h>
+
+#include "hid-ids.h"
+
+/* Fixed Mi Silent Mouse report descriptor */
+/* Button's Usage Maximum changed from 3 to 5 to make side buttons work */
+#define MI_SILENT_MOUSE_ORIG_RDESC_LENGTH   87
+static const __u8 mi_silent_mouse_rdesc_fixed[] = {
+	0x05, 0x01,         /*  Usage Page (Desktop),               */
+	0x09, 0x02,         /*  Usage (Mouse),                      */
+	0xA1, 0x01,         /*  Collection (Application),           */
+	0x85, 0x03,         /*      Report ID (3),                  */
+	0x09, 0x01,         /*      Usage (Pointer),                */
+	0xA1, 0x00,         /*      Collection (Physical),          */
+	0x05, 0x09,         /*          Usage Page (Button),        */
+	0x19, 0x01,         /*          Usage Minimum (01h),        */
+	0x29, 0x05, /* X */ /*          Usage Maximum (05h),        */
+	0x15, 0x00,         /*          Logical Minimum (0),        */
+	0x25, 0x01,         /*          Logical Maximum (1),        */
+	0x75, 0x01,         /*          Report Size (1),            */
+	0x95, 0x05,         /*          Report Count (5),           */
+	0x81, 0x02,         /*          Input (Variable),           */
+	0x75, 0x03,         /*          Report Size (3),            */
+	0x95, 0x01,         /*          Report Count (1),           */
+	0x81, 0x01,         /*          Input (Constant),           */
+	0x05, 0x01,         /*          Usage Page (Desktop),       */
+	0x09, 0x30,         /*          Usage (X),                  */
+	0x09, 0x31,         /*          Usage (Y),                  */
+	0x15, 0x81,         /*          Logical Minimum (-127),     */
+	0x25, 0x7F,         /*          Logical Maximum (127),      */
+	0x75, 0x08,         /*          Report Size (8),            */
+	0x95, 0x02,         /*          Report Count (2),           */
+	0x81, 0x06,         /*          Input (Variable, Relative), */
+	0x09, 0x38,         /*          Usage (Wheel),              */
+	0x15, 0x81,         /*          Logical Minimum (-127),     */
+	0x25, 0x7F,         /*          Logical Maximum (127),      */
+	0x75, 0x08,         /*          Report Size (8),            */
+	0x95, 0x01,         /*          Report Count (1),           */
+	0x81, 0x06,         /*          Input (Variable, Relative), */
+	0xC0,               /*      End Collection,                 */
+	0xC0,               /*  End Collection,                     */
+	0x06, 0x01, 0xFF,   /*  Usage Page (FF01h),                 */
+	0x09, 0x01,         /*  Usage (01h),                        */
+	0xA1, 0x01,         /*  Collection (Application),           */
+	0x85, 0x05,         /*      Report ID (5),                  */
+	0x09, 0x05,         /*      Usage (05h),                    */
+	0x15, 0x00,         /*      Logical Minimum (0),            */
+	0x26, 0xFF, 0x00,   /*      Logical Maximum (255),          */
+	0x75, 0x08,         /*      Report Size (8),                */
+	0x95, 0x04,         /*      Report Count (4),               */
+	0xB1, 0x02,         /*      Feature (Variable),             */
+	0xC0                /*  End Collection                      */
+};
+
+static const __u8 *xiaomi_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+				       unsigned int *rsize)
+{
+	switch (hdev->product) {
+	case USB_DEVICE_ID_MI_SILENT_MOUSE:
+		if (*rsize == MI_SILENT_MOUSE_ORIG_RDESC_LENGTH) {
+			hid_info(hdev, "fixing up Mi Silent Mouse report descriptor\n");
+			*rsize = sizeof(mi_silent_mouse_rdesc_fixed);
+			return mi_silent_mouse_rdesc_fixed;
+		}
+		break;
+	}
+	return rdesc;
+}
+
+static const struct hid_device_id xiaomi_devices[] = {
+	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_XIAOMI, USB_DEVICE_ID_MI_SILENT_MOUSE) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, xiaomi_devices);
+
+static struct hid_driver xiaomi_driver = {
+	.name = "xiaomi",
+	.id_table = xiaomi_devices,
+	.report_fixup = xiaomi_report_fixup,
+};
+module_hid_driver(xiaomi_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ilya Skriblovsky <IlyaSkriblovsky@gmail.com>");
+MODULE_DESCRIPTION("Fixing side buttons of Xiaomi Mi Silent Mouse");