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, 51 insertions, 0 deletions

diff --git a/fs/jffs2/writev.c b/fs/jffs2/writev.c
new file mode 100644
index 000000000..a1bda9dab
--- /dev/null
+++ b/fs/jffs2/writev.c
@@ -0,0 +1,51 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2001-2007 Red Hat, Inc.
+ *
+ * Created by David Woodhouse <dwmw2@infradead.org>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/mtd/mtd.h>
+#include "nodelist.h"
+
+int jffs2_flash_direct_writev(struct jffs2_sb_info *c, const struct kvec *vecs,
+			      unsigned long count, loff_t to, size_t *retlen)
+{
+	if (!jffs2_is_writebuffered(c)) {
+		if (jffs2_sum_active()) {
+			int res;
+			res = jffs2_sum_add_kvec(c, vecs, count, (uint32_t) to);
+			if (res) {
+				return res;
+			}
+		}
+	}
+
+	return mtd_writev(c->mtd, vecs, count, to, retlen);
+}
+
+int jffs2_flash_direct_write(struct jffs2_sb_info *c, loff_t ofs, size_t len,
+			size_t *retlen, const u_char *buf)
+{
+	int ret;
+	ret = mtd_write(c->mtd, ofs, len, retlen, buf);
+
+	if (jffs2_sum_active()) {
+		struct kvec vecs[1];
+		int res;
+
+		vecs[0].iov_base = (unsigned char *) buf;
+		vecs[0].iov_len = len;
+
+		res = jffs2_sum_add_kvec(c, vecs, 1, (uint32_t) ofs);
+		if (res) {
+			return res;
+		}
+	}
+	return ret;
+}