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, 63 insertions, 0 deletions

diff --git a/drivers/video/fbdev/sbuslib.h b/drivers/video/fbdev/sbuslib.h
new file mode 100644
index 000000000..e9af2dc93
--- /dev/null
+++ b/drivers/video/fbdev/sbuslib.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* sbuslib.h: SBUS fb helper library interfaces */
+#ifndef _SBUSLIB_H
+#define _SBUSLIB_H
+
+struct device_node;
+struct fb_info;
+struct fb_var_screeninfo;
+struct vm_area_struct;
+
+struct sbus_mmap_map {
+	unsigned long voff;
+	unsigned long poff;
+	unsigned long size;
+};
+
+#define SBUS_MMAP_FBSIZE(n) (-n)
+#define SBUS_MMAP_EMPTY	0x80000000
+
+extern void sbusfb_fill_var(struct fb_var_screeninfo *var,
+			    struct device_node *dp, int bpp);
+extern int sbusfb_mmap_helper(const struct sbus_mmap_map *map,
+			      unsigned long physbase, unsigned long fbsize,
+			      unsigned long iospace,
+			      struct vm_area_struct *vma);
+int sbusfb_ioctl_helper(unsigned long cmd, unsigned long arg,
+			struct fb_info *info,
+			int type, int fb_depth, unsigned long fb_size);
+int sbusfb_compat_ioctl(struct fb_info *info, unsigned int cmd,
+			unsigned long arg);
+
+/*
+ * Initialize struct fb_ops for SBUS I/O.
+ */
+
+#define __FB_DEFAULT_SBUS_OPS_RDWR(__prefix) \
+	.fb_read	= fb_io_read, \
+	.fb_write	= fb_io_write
+
+#define __FB_DEFAULT_SBUS_OPS_DRAW(__prefix) \
+	.fb_fillrect	= cfb_fillrect, \
+	.fb_copyarea	= cfb_copyarea, \
+	.fb_imageblit	= cfb_imageblit
+
+#ifdef CONFIG_COMPAT
+#define __FB_DEFAULT_SBUS_OPS_IOCTL(__prefix) \
+	.fb_ioctl		= __prefix ## _sbusfb_ioctl, \
+	.fb_compat_ioctl	= sbusfb_compat_ioctl
+#else
+#define __FB_DEFAULT_SBUS_OPS_IOCTL(__prefix) \
+	.fb_ioctl	= __prefix ## _sbusfb_ioctl
+#endif
+
+#define __FB_DEFAULT_SBUS_OPS_MMAP(__prefix) \
+	.fb_mmap	= __prefix ## _sbusfb_mmap
+
+#define FB_DEFAULT_SBUS_OPS(__prefix) \
+	__FB_DEFAULT_SBUS_OPS_RDWR(__prefix), \
+	__FB_DEFAULT_SBUS_OPS_DRAW(__prefix), \
+	__FB_DEFAULT_SBUS_OPS_IOCTL(__prefix), \
+	__FB_DEFAULT_SBUS_OPS_MMAP(__prefix)
+
+#endif /* _SBUSLIB_H */