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, 174 insertions, 0 deletions

diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c
new file mode 100644
index 000000000..2386d08bf
--- /dev/null
+++ b/drivers/md/bcache/io.c
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Some low level IO code, and hacks for various block layer limitations
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "bset.h"
+#include "debug.h"
+
+#include <linux/blkdev.h>
+
+/* Bios with headers */
+
+void bch_bbio_free(struct bio *bio, struct cache_set *c)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+
+	mempool_free(b, &c->bio_meta);
+}
+
+struct bio *bch_bbio_alloc(struct cache_set *c)
+{
+	struct bbio *b = mempool_alloc(&c->bio_meta, GFP_NOIO);
+	struct bio *bio = &b->bio;
+
+	bio_init_inline(bio, NULL, meta_bucket_pages(&c->cache->sb), 0);
+
+	return bio;
+}
+
+void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+
+	bio->bi_iter.bi_sector	= PTR_OFFSET(&b->key, 0);
+	bio_set_dev(bio, c->cache->bdev);
+
+	b->submit_time_us = local_clock_us();
+	closure_bio_submit(c, bio, bio->bi_private);
+}
+
+void bch_submit_bbio(struct bio *bio, struct cache_set *c,
+		     struct bkey *k, unsigned int ptr)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+
+	bch_bkey_copy_single_ptr(&b->key, k, ptr);
+	__bch_submit_bbio(bio, c);
+}
+
+/* IO errors */
+void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio)
+{
+	unsigned int errors;
+
+	WARN_ONCE(!dc, "NULL pointer of struct cached_dev");
+
+	/*
+	 * Read-ahead requests on a degrading and recovering md raid
+	 * (e.g. raid6) device might be failured immediately by md
+	 * raid code, which is not a real hardware media failure. So
+	 * we shouldn't count failed REQ_RAHEAD bio to dc->io_errors.
+	 */
+	if (bio->bi_opf & REQ_RAHEAD) {
+		pr_warn_ratelimited("%pg: Read-ahead I/O failed on backing device, ignore\n",
+				    dc->bdev);
+		return;
+	}
+
+	errors = atomic_add_return(1, &dc->io_errors);
+	if (errors < dc->error_limit)
+		pr_err("%pg: IO error on backing device, unrecoverable\n",
+			dc->bdev);
+	else
+		bch_cached_dev_error(dc);
+}
+
+void bch_count_io_errors(struct cache *ca,
+			 blk_status_t error,
+			 int is_read,
+			 const char *m)
+{
+	/*
+	 * The halflife of an error is:
+	 * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
+	 */
+
+	if (ca->set->error_decay) {
+		unsigned int count = atomic_inc_return(&ca->io_count);
+
+		while (count > ca->set->error_decay) {
+			unsigned int errors;
+			unsigned int old = count;
+			unsigned int new = count - ca->set->error_decay;
+
+			/*
+			 * First we subtract refresh from count; each time we
+			 * successfully do so, we rescale the errors once:
+			 */
+
+			count = atomic_cmpxchg(&ca->io_count, old, new);
+
+			if (count == old) {
+				count = new;
+
+				errors = atomic_read(&ca->io_errors);
+				do {
+					old = errors;
+					new = ((uint64_t) errors * 127) / 128;
+					errors = atomic_cmpxchg(&ca->io_errors,
+								old, new);
+				} while (old != errors);
+			}
+		}
+	}
+
+	if (error) {
+		unsigned int errors = atomic_add_return(1 << IO_ERROR_SHIFT,
+						    &ca->io_errors);
+		errors >>= IO_ERROR_SHIFT;
+
+		if (errors < ca->set->error_limit)
+			pr_err("%pg: IO error on %s%s\n",
+			       ca->bdev, m,
+			       is_read ? ", recovering." : ".");
+		else
+			bch_cache_set_error(ca->set,
+					    "%pg: too many IO errors %s\n",
+					    ca->bdev, m);
+	}
+}
+
+void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
+			      blk_status_t error, const char *m)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+	struct cache *ca = c->cache;
+	int is_read = (bio_data_dir(bio) == READ ? 1 : 0);
+
+	unsigned int threshold = op_is_write(bio_op(bio))
+		? c->congested_write_threshold_us
+		: c->congested_read_threshold_us;
+
+	if (threshold) {
+		unsigned int t = local_clock_us();
+		int us = t - b->submit_time_us;
+		int congested = atomic_read(&c->congested);
+
+		if (us > (int) threshold) {
+			int ms = us / 1024;
+
+			c->congested_last_us = t;
+
+			ms = min(ms, CONGESTED_MAX + congested);
+			atomic_sub(ms, &c->congested);
+		} else if (congested < 0)
+			atomic_inc(&c->congested);
+	}
+
+	bch_count_io_errors(ca, error, is_read, m);
+}
+
+void bch_bbio_endio(struct cache_set *c, struct bio *bio,
+		    blk_status_t error, const char *m)
+{
+	struct closure *cl = bio->bi_private;
+
+	bch_bbio_count_io_errors(c, bio, error, m);
+	bio_put(bio);
+	closure_put(cl);
+}