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, 217 insertions, 0 deletions

diff --git a/fs/erofs/fileio.c b/fs/erofs/fileio.c
new file mode 100644
index 000000000..ebb81a7ff
--- /dev/null
+++ b/fs/erofs/fileio.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2024, Alibaba Cloud
+ */
+#include "internal.h"
+#include <trace/events/erofs.h>
+
+struct erofs_fileio_rq {
+	struct bio_vec bvecs[16];
+	struct bio bio;
+	struct kiocb iocb;
+	struct super_block *sb;
+	refcount_t ref;
+};
+
+struct erofs_fileio {
+	struct erofs_map_blocks map;
+	struct erofs_map_dev dev;
+	struct erofs_fileio_rq *rq;
+};
+
+static void erofs_fileio_ki_complete(struct kiocb *iocb, long ret)
+{
+	struct erofs_fileio_rq *rq =
+			container_of(iocb, struct erofs_fileio_rq, iocb);
+	struct folio_iter fi;
+
+	if (ret >= 0 && ret != rq->bio.bi_iter.bi_size)
+		ret = -EIO;
+	if (!rq->bio.bi_end_io) {
+		bio_for_each_folio_all(fi, &rq->bio) {
+			DBG_BUGON(folio_test_uptodate(fi.folio));
+			erofs_onlinefolio_end(fi.folio, ret < 0, false);
+		}
+	} else if (ret < 0 && !rq->bio.bi_status) {
+		rq->bio.bi_status = errno_to_blk_status(ret);
+	}
+	bio_endio(&rq->bio);
+	bio_uninit(&rq->bio);
+	if (refcount_dec_and_test(&rq->ref))
+		kfree(rq);
+}
+
+static void erofs_fileio_rq_submit(struct erofs_fileio_rq *rq)
+{
+	struct iov_iter iter;
+	ssize_t ret;
+
+	if (!rq)
+		return;
+	rq->iocb.ki_pos = rq->bio.bi_iter.bi_sector << SECTOR_SHIFT;
+	rq->iocb.ki_ioprio = get_current_ioprio();
+	rq->iocb.ki_complete = erofs_fileio_ki_complete;
+	if (test_opt(&EROFS_SB(rq->sb)->opt, DIRECT_IO) &&
+	    rq->iocb.ki_filp->f_mode & FMODE_CAN_ODIRECT)
+		rq->iocb.ki_flags = IOCB_DIRECT;
+	iov_iter_bvec(&iter, ITER_DEST, rq->bvecs, rq->bio.bi_vcnt,
+		      rq->bio.bi_iter.bi_size);
+	scoped_with_creds(rq->iocb.ki_filp->f_cred)
+		ret = vfs_iocb_iter_read(rq->iocb.ki_filp, &rq->iocb, &iter);
+	if (ret != -EIOCBQUEUED)
+		erofs_fileio_ki_complete(&rq->iocb, ret);
+	if (refcount_dec_and_test(&rq->ref))
+		kfree(rq);
+}
+
+static struct erofs_fileio_rq *erofs_fileio_rq_alloc(struct erofs_map_dev *mdev)
+{
+	struct erofs_fileio_rq *rq = kzalloc_obj(*rq, GFP_KERNEL | __GFP_NOFAIL);
+
+	bio_init(&rq->bio, NULL, rq->bvecs, ARRAY_SIZE(rq->bvecs), REQ_OP_READ);
+	rq->iocb.ki_filp = mdev->m_dif->file;
+	rq->sb = mdev->m_sb;
+	refcount_set(&rq->ref, 2);
+	return rq;
+}
+
+struct bio *erofs_fileio_bio_alloc(struct erofs_map_dev *mdev)
+{
+	return &erofs_fileio_rq_alloc(mdev)->bio;
+}
+
+void erofs_fileio_submit_bio(struct bio *bio)
+{
+	return erofs_fileio_rq_submit(container_of(bio, struct erofs_fileio_rq,
+						   bio));
+}
+
+static int erofs_fileio_scan_folio(struct erofs_fileio *io,
+				   struct inode *inode, struct folio *folio)
+{
+	struct erofs_map_blocks *map = &io->map;
+	unsigned int cur = 0, end = folio_size(folio), len, attached = 0;
+	loff_t pos = folio_pos(folio), ofs;
+	int err = 0;
+
+	erofs_onlinefolio_init(folio);
+	while (cur < end) {
+		if (!in_range(pos + cur, map->m_la, map->m_llen)) {
+			map->m_la = pos + cur;
+			map->m_llen = end - cur;
+			err = erofs_map_blocks(inode, map);
+			if (err)
+				break;
+		}
+
+		ofs = folio_pos(folio) + cur - map->m_la;
+		len = min_t(loff_t, map->m_llen - ofs, end - cur);
+		if (map->m_flags & EROFS_MAP_META) {
+			struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
+			void *src;
+
+			src = erofs_read_metabuf(&buf, inode->i_sb,
+				map->m_pa + ofs, erofs_inode_in_metabox(inode));
+			if (IS_ERR(src)) {
+				err = PTR_ERR(src);
+				break;
+			}
+			memcpy_to_folio(folio, cur, src, len);
+			erofs_put_metabuf(&buf);
+		} else if (!(map->m_flags & EROFS_MAP_MAPPED)) {
+			folio_zero_segment(folio, cur, cur + len);
+			attached = 0;
+		} else {
+			if (io->rq && (map->m_pa + ofs != io->dev.m_pa ||
+				       map->m_deviceid != io->dev.m_deviceid)) {
+io_retry:
+				erofs_fileio_rq_submit(io->rq);
+				io->rq = NULL;
+			}
+
+			if (!io->rq) {
+				io->dev = (struct erofs_map_dev) {
+					.m_pa = io->map.m_pa + ofs,
+					.m_deviceid = io->map.m_deviceid,
+				};
+				err = erofs_map_dev(inode->i_sb, &io->dev);
+				if (err)
+					break;
+				io->rq = erofs_fileio_rq_alloc(&io->dev);
+				io->rq->bio.bi_iter.bi_sector =
+					(io->dev.m_dif->fsoff + io->dev.m_pa) >> 9;
+				attached = 0;
+			}
+			if (!bio_add_folio(&io->rq->bio, folio, len, cur))
+				goto io_retry;
+			if (!attached++)
+				erofs_onlinefolio_split(folio);
+			io->dev.m_pa += len;
+		}
+		cur += len;
+	}
+	erofs_onlinefolio_end(folio, err, false);
+	return err;
+}
+
+static int erofs_fileio_read_folio(struct file *file, struct folio *folio)
+{
+	bool need_iput;
+	struct inode *realinode = erofs_real_inode(folio_inode(folio), &need_iput);
+	struct erofs_fileio io = {};
+	int err;
+
+	trace_erofs_read_folio(realinode, folio, true);
+	err = erofs_fileio_scan_folio(&io, realinode, folio);
+	erofs_fileio_rq_submit(io.rq);
+	if (need_iput)
+		iput(realinode);
+	return err;
+}
+
+static void erofs_fileio_readahead(struct readahead_control *rac)
+{
+	bool need_iput;
+	struct inode *realinode = erofs_real_inode(rac->mapping->host, &need_iput);
+	struct erofs_fileio io = {};
+	struct folio *folio;
+	int err;
+
+	trace_erofs_readahead(realinode, readahead_index(rac),
+			      readahead_count(rac), true);
+	while ((folio = readahead_folio(rac))) {
+		err = erofs_fileio_scan_folio(&io, realinode, folio);
+		if (err && err != -EINTR)
+			erofs_err(realinode->i_sb, "readahead error at folio %lu @ nid %llu",
+				  folio->index, EROFS_I(realinode)->nid);
+	}
+	erofs_fileio_rq_submit(io.rq);
+	if (need_iput)
+		iput(realinode);
+}
+
+const struct address_space_operations erofs_fileio_aops = {
+	.read_folio = erofs_fileio_read_folio,
+	.readahead = erofs_fileio_readahead,
+};
+
+int erofs_read_meta_folio(struct file *file, struct folio *folio)
+{
+	struct erofs_fileio io = {
+		.dev = { .m_pa = folio_pos(folio), },
+	};
+	struct inode *inode = folio_inode(folio);
+	int err;
+
+	err = erofs_map_dev(inode->i_sb, &io.dev);
+	if (err)
+		return err;
+
+	io.rq = erofs_fileio_rq_alloc(&io.dev);
+	io.rq->bio.bi_iter.bi_sector =
+		(io.dev.m_dif->fsoff + io.dev.m_pa) >> 9;
+	erofs_onlinefolio_init(folio);
+	bio_add_folio_nofail(&io.rq->bio, folio, folio_size(folio), 0);
+	erofs_fileio_rq_submit(io.rq);
+	return 0;
+}