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, 168 insertions, 0 deletions

diff --git a/fs/smb/client/fscache.c b/fs/smb/client/fscache.c
new file mode 100644
index 000000000..9f66bbcd3
--- /dev/null
+++ b/fs/smb/client/fscache.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ *   CIFS filesystem cache interface
+ *
+ *   Copyright (c) 2010 Novell, Inc.
+ *   Author(s): Suresh Jayaraman <sjayaraman@suse.de>
+ *
+ */
+#include "fscache.h"
+#include "cifsglob.h"
+#include "cifs_debug.h"
+#include "cifs_fs_sb.h"
+#include "cifsproto.h"
+
+/*
+ * Key for fscache inode.  [!] Contents must match comparisons in cifs_find_inode().
+ */
+struct cifs_fscache_inode_key {
+
+	__le64  uniqueid;	/* server inode number */
+	__le64  createtime;	/* creation time on server */
+	u8	type;		/* S_IFMT file type */
+} __packed;
+
+static void cifs_fscache_fill_volume_coherency(
+	struct cifs_tcon *tcon,
+	struct cifs_fscache_volume_coherency_data *cd)
+{
+	memset(cd, 0, sizeof(*cd));
+	cd->resource_id		= cpu_to_le64(tcon->resource_id);
+	cd->vol_create_time	= tcon->vol_create_time;
+	cd->vol_serial_number	= cpu_to_le32(tcon->vol_serial_number);
+}
+
+int cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
+{
+	struct cifs_fscache_volume_coherency_data cd;
+	struct TCP_Server_Info *server = tcon->ses->server;
+	struct fscache_volume *vcookie;
+	const struct sockaddr *sa = (struct sockaddr *)&server->dstaddr;
+	char *sharename;
+	char *key;
+	int ret = -ENOMEM;
+
+	if (tcon->fscache_acquired)
+		return 0;
+
+	mutex_lock(&tcon->fscache_lock);
+	if (tcon->fscache_acquired) {
+		mutex_unlock(&tcon->fscache_lock);
+		return 0;
+	}
+	tcon->fscache_acquired = true;
+
+	tcon->fscache = NULL;
+	switch (sa->sa_family) {
+	case AF_INET:
+	case AF_INET6:
+		break;
+	default:
+		mutex_unlock(&tcon->fscache_lock);
+		cifs_dbg(VFS, "Unknown network family '%d'\n", sa->sa_family);
+		return -EINVAL;
+	}
+
+	memset(&key, 0, sizeof(key));
+
+	sharename = extract_sharename(tcon->tree_name);
+	if (IS_ERR(sharename)) {
+		mutex_unlock(&tcon->fscache_lock);
+		cifs_dbg(FYI, "%s: couldn't extract sharename\n", __func__);
+		return PTR_ERR(sharename);
+	}
+
+	strreplace(sharename, '/', ';');
+
+	key = kasprintf(GFP_KERNEL, "cifs,%pISpc,%s", sa, sharename);
+	if (!key)
+		goto out;
+
+	cifs_fscache_fill_volume_coherency(tcon, &cd);
+	vcookie = fscache_acquire_volume(key,
+					 NULL, /* preferred_cache */
+					 &cd, sizeof(cd));
+	cifs_dbg(FYI, "%s: (%s/0x%p)\n", __func__, key, vcookie);
+	if (IS_ERR(vcookie)) {
+		if (vcookie != ERR_PTR(-EBUSY)) {
+			ret = PTR_ERR(vcookie);
+			goto out_2;
+		}
+		pr_err("Cache volume key already in use (%s)\n", key);
+		vcookie = NULL;
+		trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
+				    netfs_trace_tcon_ref_see_fscache_collision);
+	} else {
+		trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
+				    netfs_trace_tcon_ref_see_fscache_okay);
+	}
+
+	tcon->fscache = vcookie;
+	ret = 0;
+out_2:
+	kfree(key);
+out:
+	kfree(sharename);
+	mutex_unlock(&tcon->fscache_lock);
+	return ret;
+}
+
+void cifs_fscache_release_super_cookie(struct cifs_tcon *tcon)
+{
+	struct cifs_fscache_volume_coherency_data cd;
+
+	cifs_dbg(FYI, "%s: (0x%p)\n", __func__, tcon->fscache);
+
+	cifs_fscache_fill_volume_coherency(tcon, &cd);
+	fscache_relinquish_volume(tcon->fscache, &cd, false);
+	tcon->fscache = NULL;
+	trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
+			    netfs_trace_tcon_ref_see_fscache_relinq);
+}
+
+void cifs_fscache_get_inode_cookie(struct inode *inode)
+{
+	struct cifs_fscache_inode_coherency_data cd;
+	struct cifs_fscache_inode_key key;
+	struct cifsInodeInfo *cifsi = CIFS_I(inode);
+	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
+	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+
+	key.uniqueid	= cpu_to_le64(cifsi->uniqueid);
+	key.createtime	= cpu_to_le64(cifsi->createtime);
+	key.type	= (inode->i_mode & S_IFMT) >> 12;
+	cifs_fscache_fill_coherency(&cifsi->netfs.inode, &cd);
+
+	cifsi->netfs.cache =
+		fscache_acquire_cookie(tcon->fscache, 0,
+				       &key, sizeof(key),
+				       &cd, sizeof(cd),
+				       i_size_read(&cifsi->netfs.inode));
+	if (cifsi->netfs.cache)
+		mapping_set_release_always(inode->i_mapping);
+}
+
+void cifs_fscache_unuse_inode_cookie(struct inode *inode, bool update)
+{
+	if (update) {
+		struct cifs_fscache_inode_coherency_data cd;
+		loff_t i_size = i_size_read(inode);
+
+		cifs_fscache_fill_coherency(inode, &cd);
+		fscache_unuse_cookie(cifs_inode_cookie(inode), &cd, &i_size);
+	} else {
+		fscache_unuse_cookie(cifs_inode_cookie(inode), NULL, NULL);
+	}
+}
+
+void cifs_fscache_release_inode_cookie(struct inode *inode)
+{
+	struct cifsInodeInfo *cifsi = CIFS_I(inode);
+	struct fscache_cookie *cookie = cifs_inode_cookie(inode);
+
+	if (cookie) {
+		cifs_dbg(FYI, "%s: (0x%p)\n", __func__, cookie);
+		fscache_relinquish_cookie(cookie, false);
+		cifsi->netfs.cache = NULL;
+	}
+}