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, 179 insertions, 0 deletions

diff --git a/fs/coda/cnode.c b/fs/coda/cnode.c
new file mode 100644
index 000000000..70bb0579b
--- /dev/null
+++ b/fs/coda/cnode.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0
+/* cnode related routines for the coda kernel code
+   (C) 1996 Peter Braam
+   */
+
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/time.h>
+
+#include <linux/coda.h>
+#include <linux/pagemap.h>
+#include "coda_psdev.h"
+#include "coda_linux.h"
+
+static inline int coda_fideq(struct CodaFid *fid1, struct CodaFid *fid2)
+{
+	return memcmp(fid1, fid2, sizeof(*fid1)) == 0;
+}
+
+static const struct inode_operations coda_symlink_inode_operations = {
+	.get_link	= page_get_link,
+	.setattr	= coda_setattr,
+};
+
+/* cnode.c */
+static void coda_fill_inode(struct inode *inode, struct coda_vattr *attr)
+{
+        coda_vattr_to_iattr(inode, attr);
+
+        if (S_ISREG(inode->i_mode)) {
+                inode->i_op = &coda_file_inode_operations;
+                inode->i_fop = &coda_file_operations;
+        } else if (S_ISDIR(inode->i_mode)) {
+                inode->i_op = &coda_dir_inode_operations;
+                inode->i_fop = &coda_dir_operations;
+        } else if (S_ISLNK(inode->i_mode)) {
+		inode->i_op = &coda_symlink_inode_operations;
+		inode_nohighmem(inode);
+		inode->i_data.a_ops = &coda_symlink_aops;
+		inode->i_mapping = &inode->i_data;
+	} else
+                init_special_inode(inode, inode->i_mode, huge_decode_dev(attr->va_rdev));
+}
+
+static int coda_test_inode(struct inode *inode, void *data)
+{
+	struct CodaFid *fid = (struct CodaFid *)data;
+	struct coda_inode_info *cii = ITOC(inode);
+	return coda_fideq(&cii->c_fid, fid);
+}
+
+static int coda_set_inode(struct inode *inode, void *data)
+{
+	struct CodaFid *fid = (struct CodaFid *)data;
+	struct coda_inode_info *cii = ITOC(inode);
+	cii->c_fid = *fid;
+	return 0;
+}
+
+struct inode * coda_iget(struct super_block * sb, struct CodaFid * fid,
+			 struct coda_vattr * attr)
+{
+	struct inode *inode;
+	struct coda_inode_info *cii;
+	unsigned long hash = coda_f2i(fid);
+	umode_t inode_type = coda_inode_type(attr);
+
+retry:
+	inode = iget5_locked(sb, hash, coda_test_inode, coda_set_inode, fid);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	if (inode_state_read_once(inode) & I_NEW) {
+		cii = ITOC(inode);
+		/* we still need to set i_ino for things like stat(2) */
+		inode->i_ino = hash;
+		/* inode is locked and unique, no need to grab cii->c_lock */
+		cii->c_mapcount = 0;
+		coda_fill_inode(inode, attr);
+		unlock_new_inode(inode);
+	} else if ((inode->i_mode & S_IFMT) != inode_type) {
+		/* Inode has changed type, mark bad and grab a new one */
+		remove_inode_hash(inode);
+		coda_flag_inode(inode, C_PURGE);
+		iput(inode);
+		goto retry;
+	}
+	return inode;
+}
+
+/* this is effectively coda_iget:
+   - get attributes (might be cached)
+   - get the inode for the fid using vfs iget
+   - link the two up if this is needed
+   - fill in the attributes
+*/
+struct inode *coda_cnode_make(struct CodaFid *fid, struct super_block *sb)
+{
+        struct coda_vattr attr;
+	struct inode *inode;
+        int error;
+        
+	/* We get inode numbers from Venus -- see venus source */
+	error = venus_getattr(sb, fid, &attr);
+	if (error)
+		return ERR_PTR(error);
+
+	inode = coda_iget(sb, fid, &attr);
+	if (IS_ERR(inode))
+		pr_warn("%s: coda_iget failed\n", __func__);
+	return inode;
+}
+
+
+/* Although we treat Coda file identifiers as immutable, there is one
+ * special case for files created during a disconnection where they may
+ * not be globally unique. When an identifier collision is detected we
+ * first try to flush the cached inode from the kernel and finally
+ * resort to renaming/rehashing in-place. Userspace remembers both old
+ * and new values of the identifier to handle any in-flight upcalls.
+ * The real solution is to use globally unique UUIDs as identifiers, but
+ * retrofitting the existing userspace code for this is non-trivial. */
+void coda_replace_fid(struct inode *inode, struct CodaFid *oldfid, 
+		      struct CodaFid *newfid)
+{
+	struct coda_inode_info *cii = ITOC(inode);
+	unsigned long hash = coda_f2i(newfid);
+	
+	BUG_ON(!coda_fideq(&cii->c_fid, oldfid));
+
+	/* replace fid and rehash inode */
+	/* XXX we probably need to hold some lock here! */
+	remove_inode_hash(inode);
+	cii->c_fid = *newfid;
+	inode->i_ino = hash;
+	__insert_inode_hash(inode, hash);
+}
+
+/* convert a fid to an inode. */
+struct inode *coda_fid_to_inode(struct CodaFid *fid, struct super_block *sb) 
+{
+	struct inode *inode;
+	unsigned long hash = coda_f2i(fid);
+
+	inode = ilookup5(sb, hash, coda_test_inode, fid);
+	if ( !inode )
+		return NULL;
+
+	/* we should never see newly created inodes because we intentionally
+	 * fail in the initialization callback */
+	BUG_ON(inode_state_read_once(inode) & I_NEW);
+
+	return inode;
+}
+
+struct coda_file_info *coda_ftoc(struct file *file)
+{
+	struct coda_file_info *cfi = file->private_data;
+
+	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
+
+	return cfi;
+
+}
+
+/* the CONTROL inode is made without asking attributes from Venus */
+struct inode *coda_cnode_makectl(struct super_block *sb)
+{
+	struct inode *inode = new_inode(sb);
+	if (inode) {
+		inode->i_ino = CTL_INO;
+		inode->i_op = &coda_ioctl_inode_operations;
+		inode->i_fop = &coda_ioctl_operations;
+		inode->i_mode = 0444;
+		return inode;
+	}
+	return ERR_PTR(-ENOMEM);
+}
+