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, 127 insertions, 0 deletions

diff --git a/block/bio-integrity-auto.c b/block/bio-integrity-auto.c
new file mode 100644
index 000000000..9456dcffd
--- /dev/null
+++ b/block/bio-integrity-auto.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007, 2008, 2009 Oracle Corporation
+ * Written by: Martin K. Petersen <martin.petersen@oracle.com>
+ *
+ * Automatically generate and verify integrity data on PI capable devices if the
+ * bio submitter didn't provide PI itself.  This ensures that kernel verifies
+ * data integrity even if the file system (or other user of the block device) is
+ * not aware of PI.
+ */
+#include <linux/blk-integrity.h>
+#include <linux/t10-pi.h>
+#include <linux/workqueue.h>
+#include "blk.h"
+
+struct bio_integrity_data {
+	struct bio			*bio;
+	struct bvec_iter		saved_bio_iter;
+	struct work_struct		work;
+	struct bio_integrity_payload	bip;
+	struct bio_vec			bvec;
+};
+
+static struct kmem_cache *bid_slab;
+static mempool_t bid_pool;
+static struct workqueue_struct *kintegrityd_wq;
+
+static void bio_integrity_finish(struct bio_integrity_data *bid)
+{
+	bid->bio->bi_integrity = NULL;
+	bid->bio->bi_opf &= ~REQ_INTEGRITY;
+	bio_integrity_free_buf(&bid->bip);
+	mempool_free(bid, &bid_pool);
+}
+
+static void bio_integrity_verify_fn(struct work_struct *work)
+{
+	struct bio_integrity_data *bid =
+		container_of(work, struct bio_integrity_data, work);
+	struct bio *bio = bid->bio;
+
+	bio->bi_status = bio_integrity_verify(bio, &bid->saved_bio_iter);
+	bio_integrity_finish(bid);
+	bio_endio(bio);
+}
+
+/**
+ * __bio_integrity_endio - Integrity I/O completion function
+ * @bio:	Protected bio
+ *
+ * Normally I/O completion is done in interrupt context.  However, verifying I/O
+ * integrity is a time-consuming task which must be run in process context.
+ *
+ * This function postpones completion accordingly.
+ */
+bool __bio_integrity_endio(struct bio *bio)
+{
+	struct bio_integrity_payload *bip = bio_integrity(bio);
+	struct bio_integrity_data *bid =
+		container_of(bip, struct bio_integrity_data, bip);
+
+	if (bio_op(bio) == REQ_OP_READ && !bio->bi_status &&
+	    (bip->bip_flags & BIP_CHECK_FLAGS)) {
+		INIT_WORK(&bid->work, bio_integrity_verify_fn);
+		queue_work(kintegrityd_wq, &bid->work);
+		return false;
+	}
+
+	bio_integrity_finish(bid);
+	return true;
+}
+
+/**
+ * bio_integrity_prep - Prepare bio for integrity I/O
+ * @bio:	bio to prepare
+ * @action:	preparation action needed (BI_ACT_*)
+ *
+ * Allocate the integrity payload.  For writes, generate the integrity metadata
+ * and for reads, setup the completion handler to verify the metadata.
+ *
+ * This is used for bios that do not have user integrity payloads attached.
+ */
+void bio_integrity_prep(struct bio *bio, unsigned int action)
+{
+	struct bio_integrity_data *bid;
+
+	bid = mempool_alloc(&bid_pool, GFP_NOIO);
+	bio_integrity_init(bio, &bid->bip, &bid->bvec, 1);
+	bid->bio = bio;
+	bid->bip.bip_flags |= BIP_BLOCK_INTEGRITY;
+	bio_integrity_alloc_buf(bio, GFP_NOIO, action & BI_ACT_ZERO);
+	if (action & BI_ACT_CHECK)
+		bio_integrity_setup_default(bio);
+
+	/* Auto-generate integrity metadata if this is a write */
+	if (bio_data_dir(bio) == WRITE && (bid->bip.bip_flags & BIP_CHECK_FLAGS))
+		bio_integrity_generate(bio);
+	else
+		bid->saved_bio_iter = bio->bi_iter;
+}
+EXPORT_SYMBOL(bio_integrity_prep);
+
+void blk_flush_integrity(void)
+{
+	flush_workqueue(kintegrityd_wq);
+}
+
+static int __init blk_integrity_auto_init(void)
+{
+	bid_slab = kmem_cache_create("bio_integrity_data",
+			sizeof(struct bio_integrity_data), 0,
+			SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
+
+	if (mempool_init_slab_pool(&bid_pool, BIO_POOL_SIZE, bid_slab))
+		panic("bio: can't create integrity pool\n");
+
+	/*
+	 * kintegrityd won't block much but may burn a lot of CPU cycles.
+	 * Make it highpri CPU intensive wq with max concurrency of 1.
+	 */
+	kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
+					 WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_PERCPU, 1);
+	if (!kintegrityd_wq)
+		panic("Failed to create kintegrityd\n");
+	return 0;
+}
+subsys_initcall(blk_integrity_auto_init);