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, 223 insertions, 0 deletions

diff --git a/fs/ufs/util.c b/fs/ufs/util.c
new file mode 100644
index 000000000..dff6f7461
--- /dev/null
+++ b/fs/ufs/util.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/ufs/util.c
+ *
+ * Copyright (C) 1998
+ * Daniel Pirkl <daniel.pirkl@email.cz>
+ * Charles University, Faculty of Mathematics and Physics
+ */
+ 
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/buffer_head.h>
+
+#include "ufs_fs.h"
+#include "ufs.h"
+#include "swab.h"
+#include "util.h"
+
+struct ufs_buffer_head * _ubh_bread_ (struct ufs_sb_private_info * uspi,
+	struct super_block *sb, u64 fragment, u64 size)
+{
+	struct ufs_buffer_head * ubh;
+	unsigned i, j ;
+	u64  count = 0;
+	if (size & ~uspi->s_fmask)
+		return NULL;
+	count = size >> uspi->s_fshift;
+	if (count > UFS_MAXFRAG)
+		return NULL;
+	ubh = kmalloc_obj(struct ufs_buffer_head, GFP_NOFS);
+	if (!ubh)
+		return NULL;
+	ubh->fragment = fragment;
+	ubh->count = count;
+	for (i = 0; i < count; i++)
+		if (!(ubh->bh[i] = sb_bread(sb, fragment + i)))
+			goto failed;
+	for (; i < UFS_MAXFRAG; i++)
+		ubh->bh[i] = NULL;
+	return ubh;
+failed:
+	for (j = 0; j < i; j++)
+		brelse (ubh->bh[j]);
+	kfree(ubh);
+	return NULL;
+}
+
+struct ufs_buffer_head * ubh_bread_uspi (struct ufs_sb_private_info * uspi,
+	struct super_block *sb, u64 fragment, u64 size)
+{
+	unsigned i, j;
+	u64 count = 0;
+	if (size & ~uspi->s_fmask)
+		return NULL;
+	count = size >> uspi->s_fshift;
+	if (count <= 0 || count > UFS_MAXFRAG)
+		return NULL;
+	USPI_UBH(uspi)->fragment = fragment;
+	USPI_UBH(uspi)->count = count;
+	for (i = 0; i < count; i++)
+		if (!(USPI_UBH(uspi)->bh[i] = sb_bread(sb, fragment + i)))
+			goto failed;
+	for (; i < UFS_MAXFRAG; i++)
+		USPI_UBH(uspi)->bh[i] = NULL;
+	return USPI_UBH(uspi);
+failed:
+	for (j = 0; j < i; j++)
+		brelse (USPI_UBH(uspi)->bh[j]);
+	return NULL;
+}
+
+void ubh_brelse (struct ufs_buffer_head * ubh)
+{
+	unsigned i;
+	if (!ubh)
+		return;
+	for (i = 0; i < ubh->count; i++)
+		brelse (ubh->bh[i]);
+	kfree (ubh);
+}
+
+void ubh_brelse_uspi (struct ufs_sb_private_info * uspi)
+{
+	unsigned i;
+	if (!USPI_UBH(uspi))
+		return;
+	for ( i = 0; i < USPI_UBH(uspi)->count; i++ ) {
+		brelse (USPI_UBH(uspi)->bh[i]);
+		USPI_UBH(uspi)->bh[i] = NULL;
+	}
+}
+
+void ubh_mark_buffer_dirty (struct ufs_buffer_head * ubh)
+{
+	unsigned i;
+	if (!ubh)
+		return;
+	for ( i = 0; i < ubh->count; i++ )
+		mark_buffer_dirty (ubh->bh[i]);
+}
+
+void ubh_sync_block(struct ufs_buffer_head *ubh)
+{
+	if (ubh) {
+		unsigned i;
+
+		for (i = 0; i < ubh->count; i++)
+			write_dirty_buffer(ubh->bh[i], 0);
+
+		for (i = 0; i < ubh->count; i++)
+			wait_on_buffer(ubh->bh[i]);
+	}
+}
+
+void ubh_bforget (struct ufs_buffer_head * ubh)
+{
+	unsigned i;
+	if (!ubh) 
+		return;
+	for ( i = 0; i < ubh->count; i++ ) if ( ubh->bh[i] ) 
+		bforget (ubh->bh[i]);
+}
+ 
+int ubh_buffer_dirty (struct ufs_buffer_head * ubh)
+{
+	unsigned i;
+	unsigned result = 0;
+	if (!ubh)
+		return 0;
+	for ( i = 0; i < ubh->count; i++ )
+		result |= buffer_dirty(ubh->bh[i]);
+	return result;
+}
+
+dev_t
+ufs_get_inode_dev(struct super_block *sb, struct ufs_inode_info *ufsi)
+{
+	__u32 fs32;
+	dev_t dev;
+
+	if ((UFS_SB(sb)->s_flags & UFS_ST_MASK) == UFS_ST_SUNx86)
+		fs32 = fs32_to_cpu(sb, ufsi->i_u1.i_data[1]);
+	else
+		fs32 = fs32_to_cpu(sb, ufsi->i_u1.i_data[0]);
+	switch (UFS_SB(sb)->s_flags & UFS_ST_MASK) {
+	case UFS_ST_SUNx86:
+	case UFS_ST_SUN:
+		if ((fs32 & 0xffff0000) == 0 ||
+		    (fs32 & 0xffff0000) == 0xffff0000)
+			dev = old_decode_dev(fs32 & 0x7fff);
+		else
+			dev = MKDEV(sysv_major(fs32), sysv_minor(fs32));
+		break;
+
+	default:
+		dev = old_decode_dev(fs32);
+		break;
+	}
+	return dev;
+}
+
+void
+ufs_set_inode_dev(struct super_block *sb, struct ufs_inode_info *ufsi, dev_t dev)
+{
+	__u32 fs32;
+
+	switch (UFS_SB(sb)->s_flags & UFS_ST_MASK) {
+	case UFS_ST_SUNx86:
+	case UFS_ST_SUN:
+		fs32 = sysv_encode_dev(dev);
+		if ((fs32 & 0xffff8000) == 0) {
+			fs32 = old_encode_dev(dev);
+		}
+		break;
+
+	default:
+		fs32 = old_encode_dev(dev);
+		break;
+	}
+	if ((UFS_SB(sb)->s_flags & UFS_ST_MASK) == UFS_ST_SUNx86)
+		ufsi->i_u1.i_data[1] = cpu_to_fs32(sb, fs32);
+	else
+		ufsi->i_u1.i_data[0] = cpu_to_fs32(sb, fs32);
+}
+
+/**
+ * ufs_get_locked_folio() - locate, pin and lock a pagecache folio, if not exist
+ * read it from disk.
+ * @mapping: the address_space to search
+ * @index: the page index
+ *
+ * Locates the desired pagecache folio, if not exist we'll read it,
+ * locks it, increments its reference
+ * count and returns its address.
+ *
+ */
+struct folio *ufs_get_locked_folio(struct address_space *mapping,
+				 pgoff_t index)
+{
+	struct inode *inode = mapping->host;
+	struct folio *folio = filemap_lock_folio(mapping, index);
+	if (IS_ERR(folio)) {
+		folio = read_mapping_folio(mapping, index, NULL);
+
+		if (IS_ERR(folio)) {
+			printk(KERN_ERR "ufs_change_blocknr: read_mapping_folio error: ino %llu, index: %lu\n",
+			       mapping->host->i_ino, index);
+			return folio;
+		}
+
+		folio_lock(folio);
+
+		if (unlikely(folio->mapping == NULL)) {
+			/* Truncate got there first */
+			folio_unlock(folio);
+			folio_put(folio);
+			return NULL;
+		}
+	}
+	if (!folio_buffers(folio))
+		create_empty_buffers(folio, 1 << inode->i_blkbits, 0);
+	return folio;
+}