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, 169 insertions, 0 deletions

diff --git a/drivers/auxdisplay/cfag12864bfb.c b/drivers/auxdisplay/cfag12864bfb.c
new file mode 100644
index 000000000..24baf6b2c
--- /dev/null
+++ b/drivers/auxdisplay/cfag12864bfb.c
@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *    Filename: cfag12864bfb.c
+ *     Version: 0.1.0
+ * Description: cfag12864b LCD framebuffer driver
+ *     Depends: cfag12864b
+ *
+ *      Author: Copyright (C) Miguel Ojeda <ojeda@kernel.org>
+ *        Date: 2006-10-31
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/fb.h>
+#include <linux/mm.h>
+#include <linux/platform_device.h>
+#include <linux/cfag12864b.h>
+
+#define CFAG12864BFB_NAME "cfag12864bfb"
+
+static const struct fb_fix_screeninfo cfag12864bfb_fix = {
+	.id = "cfag12864b",
+	.type = FB_TYPE_PACKED_PIXELS,
+	.visual = FB_VISUAL_MONO10,
+	.xpanstep = 0,
+	.ypanstep = 0,
+	.ywrapstep = 0,
+	.line_length = CFAG12864B_WIDTH / 8,
+	.accel = FB_ACCEL_NONE,
+};
+
+static const struct fb_var_screeninfo cfag12864bfb_var = {
+	.xres = CFAG12864B_WIDTH,
+	.yres = CFAG12864B_HEIGHT,
+	.xres_virtual = CFAG12864B_WIDTH,
+	.yres_virtual = CFAG12864B_HEIGHT,
+	.bits_per_pixel = 1,
+	.red = { 0, 1, 0 },
+	.green = { 0, 1, 0 },
+	.blue = { 0, 1, 0 },
+	.left_margin = 0,
+	.right_margin = 0,
+	.upper_margin = 0,
+	.lower_margin = 0,
+	.vmode = FB_VMODE_NONINTERLACED,
+};
+
+static int cfag12864bfb_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+	struct page *pages = virt_to_page(cfag12864b_buffer);
+
+	vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
+
+	return vm_map_pages_zero(vma, &pages, 1);
+}
+
+static const struct fb_ops cfag12864bfb_ops = {
+	.owner = THIS_MODULE,
+	__FB_DEFAULT_SYSMEM_OPS_RDWR,
+	__FB_DEFAULT_SYSMEM_OPS_DRAW,
+	.fb_mmap = cfag12864bfb_mmap,
+};
+
+static int cfag12864bfb_probe(struct platform_device *device)
+{
+	int ret = -EINVAL;
+	struct fb_info *info = framebuffer_alloc(0, &device->dev);
+
+	if (!info)
+		goto none;
+
+	info->flags = FBINFO_VIRTFB;
+	info->screen_buffer = cfag12864b_buffer;
+	info->screen_size = CFAG12864B_SIZE;
+	info->fbops = &cfag12864bfb_ops;
+	info->fix = cfag12864bfb_fix;
+	info->var = cfag12864bfb_var;
+	info->pseudo_palette = NULL;
+	info->par = NULL;
+
+	if (register_framebuffer(info) < 0)
+		goto fballoced;
+
+	platform_set_drvdata(device, info);
+
+	fb_info(info, "%s frame buffer device\n", info->fix.id);
+
+	return 0;
+
+fballoced:
+	framebuffer_release(info);
+
+none:
+	return ret;
+}
+
+static void cfag12864bfb_remove(struct platform_device *device)
+{
+	struct fb_info *info = platform_get_drvdata(device);
+
+	if (info) {
+		unregister_framebuffer(info);
+		framebuffer_release(info);
+	}
+}
+
+static struct platform_driver cfag12864bfb_driver = {
+	.probe	= cfag12864bfb_probe,
+	.remove = cfag12864bfb_remove,
+	.driver = {
+		.name	= CFAG12864BFB_NAME,
+	},
+};
+
+static struct platform_device *cfag12864bfb_device;
+
+static int __init cfag12864bfb_init(void)
+{
+	int ret = -EINVAL;
+
+	/* cfag12864b_init() must be called first */
+	if (!cfag12864b_isinited()) {
+		printk(KERN_ERR CFAG12864BFB_NAME ": ERROR: "
+			"cfag12864b is not initialized\n");
+		goto none;
+	}
+
+	if (cfag12864b_enable()) {
+		printk(KERN_ERR CFAG12864BFB_NAME ": ERROR: "
+			"can't enable cfag12864b refreshing (being used)\n");
+		return -ENODEV;
+	}
+
+	ret = platform_driver_register(&cfag12864bfb_driver);
+
+	if (!ret) {
+		cfag12864bfb_device =
+			platform_device_alloc(CFAG12864BFB_NAME, 0);
+
+		if (cfag12864bfb_device)
+			ret = platform_device_add(cfag12864bfb_device);
+		else
+			ret = -ENOMEM;
+
+		if (ret) {
+			platform_device_put(cfag12864bfb_device);
+			platform_driver_unregister(&cfag12864bfb_driver);
+		}
+	}
+
+none:
+	return ret;
+}
+
+static void __exit cfag12864bfb_exit(void)
+{
+	platform_device_unregister(cfag12864bfb_device);
+	platform_driver_unregister(&cfag12864bfb_driver);
+	cfag12864b_disable();
+}
+
+module_init(cfag12864bfb_init);
+module_exit(cfag12864bfb_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Miguel Ojeda <ojeda@kernel.org>");
+MODULE_DESCRIPTION("cfag12864b LCD framebuffer driver");