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, 246 insertions, 0 deletions

diff --git a/fs/hfsplus/bitmap.c b/fs/hfsplus/bitmap.c
new file mode 100644
index 000000000..1b3af8c87
--- /dev/null
+++ b/fs/hfsplus/bitmap.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/hfsplus/bitmap.c
+ *
+ * Copyright (C) 2001
+ * Brad Boyer (flar@allandria.com)
+ * (C) 2003 Ardis Technologies <roman@ardistech.com>
+ *
+ * Handling of allocation file
+ */
+
+#include <linux/pagemap.h>
+
+#include "hfsplus_fs.h"
+#include "hfsplus_raw.h"
+
+#define PAGE_CACHE_BITS	(PAGE_SIZE * 8)
+
+int hfsplus_block_allocate(struct super_block *sb, u32 size,
+		u32 offset, u32 *max)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+	struct page *page;
+	struct address_space *mapping;
+	__be32 *pptr, *curr, *end;
+	u32 mask, start, len, n;
+	__be32 val;
+	int i;
+
+	len = *max;
+	if (!len)
+		return size;
+
+	hfs_dbg("size %u, offset %u, len %u\n", size, offset, len);
+	mutex_lock(&sbi->alloc_mutex);
+	mapping = sbi->alloc_file->i_mapping;
+	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL);
+	if (IS_ERR(page)) {
+		start = size;
+		goto out;
+	}
+	pptr = kmap_local_page(page);
+	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
+	i = offset % 32;
+	offset &= ~(PAGE_CACHE_BITS - 1);
+	if ((size ^ offset) / PAGE_CACHE_BITS)
+		end = pptr + PAGE_CACHE_BITS / 32;
+	else
+		end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
+
+	/* scan the first partial u32 for zero bits */
+	val = *curr;
+	if (~val) {
+		n = be32_to_cpu(val);
+		mask = (1U << 31) >> i;
+		for (; i < 32; mask >>= 1, i++) {
+			if (!(n & mask))
+				goto found;
+		}
+	}
+	curr++;
+
+	/* scan complete u32s for the first zero bit */
+	while (1) {
+		while (curr < end) {
+			val = *curr;
+			if (~val) {
+				n = be32_to_cpu(val);
+				mask = 1 << 31;
+				for (i = 0; i < 32; mask >>= 1, i++) {
+					if (!(n & mask))
+						goto found;
+				}
+			}
+			curr++;
+		}
+		kunmap_local(pptr);
+		offset += PAGE_CACHE_BITS;
+		if (offset >= size)
+			break;
+		page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
+					 NULL);
+		if (IS_ERR(page)) {
+			start = size;
+			goto out;
+		}
+		curr = pptr = kmap_local_page(page);
+		if ((size ^ offset) / PAGE_CACHE_BITS)
+			end = pptr + PAGE_CACHE_BITS / 32;
+		else
+			end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
+	}
+	hfs_dbg("bitmap full\n");
+	start = size;
+	goto out;
+
+found:
+	start = offset + (curr - pptr) * 32 + i;
+	if (start >= size) {
+		hfs_dbg("bitmap full\n");
+		goto out;
+	}
+	/* do any partial u32 at the start */
+	len = min(size - start, len);
+	while (1) {
+		n |= mask;
+		if (++i >= 32)
+			break;
+		mask >>= 1;
+		if (!--len || n & mask)
+			goto done;
+	}
+	if (!--len)
+		goto done;
+	*curr++ = cpu_to_be32(n);
+	/* do full u32s */
+	while (1) {
+		while (curr < end) {
+			n = be32_to_cpu(*curr);
+			if (len < 32)
+				goto last;
+			if (n) {
+				len = 32;
+				goto last;
+			}
+			*curr++ = cpu_to_be32(0xffffffff);
+			len -= 32;
+		}
+		set_page_dirty(page);
+		kunmap_local(pptr);
+		offset += PAGE_CACHE_BITS;
+		page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
+					 NULL);
+		if (IS_ERR(page)) {
+			start = size;
+			goto out;
+		}
+		pptr = kmap_local_page(page);
+		curr = pptr;
+		end = pptr + PAGE_CACHE_BITS / 32;
+	}
+last:
+	/* do any partial u32 at end */
+	mask = 1U << 31;
+	for (i = 0; i < len; i++) {
+		if (n & mask)
+			break;
+		n |= mask;
+		mask >>= 1;
+	}
+done:
+	*curr = cpu_to_be32(n);
+	set_page_dirty(page);
+	kunmap_local(pptr);
+	*max = offset + (curr - pptr) * 32 + i - start;
+	sbi->free_blocks -= *max;
+	hfsplus_mark_mdb_dirty(sb);
+	hfs_dbg("start %u, max %u\n", start, *max);
+out:
+	mutex_unlock(&sbi->alloc_mutex);
+	return start;
+}
+
+int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+	struct page *page;
+	struct address_space *mapping;
+	__be32 *pptr, *curr, *end;
+	u32 mask, len, pnr;
+	int i;
+
+	/* is there any actual work to be done? */
+	if (!count)
+		return 0;
+
+	hfs_dbg("offset %u, count %u\n", offset, count);
+	/* are all of the bits in range? */
+	if ((offset + count) > sbi->total_blocks)
+		return -ENOENT;
+
+	mutex_lock(&sbi->alloc_mutex);
+	mapping = sbi->alloc_file->i_mapping;
+	pnr = offset / PAGE_CACHE_BITS;
+	page = read_mapping_page(mapping, pnr, NULL);
+	if (IS_ERR(page))
+		goto kaboom;
+	pptr = kmap_local_page(page);
+	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
+	end = pptr + PAGE_CACHE_BITS / 32;
+	len = count;
+
+	/* do any partial u32 at the start */
+	i = offset % 32;
+	if (i) {
+		int j = 32 - i;
+		mask = 0xffffffffU << j;
+		if (j > count) {
+			mask |= 0xffffffffU >> (i + count);
+			*curr++ &= cpu_to_be32(mask);
+			goto out;
+		}
+		*curr++ &= cpu_to_be32(mask);
+		count -= j;
+	}
+
+	/* do full u32s */
+	while (1) {
+		while (curr < end) {
+			if (count < 32)
+				goto done;
+			*curr++ = 0;
+			count -= 32;
+		}
+		if (!count)
+			break;
+		set_page_dirty(page);
+		kunmap_local(pptr);
+		page = read_mapping_page(mapping, ++pnr, NULL);
+		if (IS_ERR(page))
+			goto kaboom;
+		pptr = kmap_local_page(page);
+		curr = pptr;
+		end = pptr + PAGE_CACHE_BITS / 32;
+	}
+done:
+	/* do any partial u32 at end */
+	if (count) {
+		mask = 0xffffffffU >> count;
+		*curr &= cpu_to_be32(mask);
+	}
+out:
+	set_page_dirty(page);
+	kunmap_local(pptr);
+	sbi->free_blocks += len;
+	hfsplus_mark_mdb_dirty(sb);
+	mutex_unlock(&sbi->alloc_mutex);
+
+	return 0;
+
+kaboom:
+	pr_crit("unable to mark blocks free: error %ld\n", PTR_ERR(page));
+	mutex_unlock(&sbi->alloc_mutex);
+
+	return -EIO;
+}