From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops 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 --- drivers/md/dm-snap-transient.c | 158 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 158 insertions(+) create mode 100644 drivers/md/dm-snap-transient.c (limited to 'drivers/md/dm-snap-transient.c') diff --git a/drivers/md/dm-snap-transient.c b/drivers/md/dm-snap-transient.c new file mode 100644 index 000000000..8680d38cd --- /dev/null +++ b/drivers/md/dm-snap-transient.c @@ -0,0 +1,158 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2001-2002 Sistina Software (UK) Limited. + * Copyright (C) 2006-2008 Red Hat GmbH + * + * This file is released under the GPL. + */ + +#include "dm-exception-store.h" + +#include +#include +#include +#include +#include +#include + +#define DM_MSG_PREFIX "transient snapshot" + +/* + *--------------------------------------------------------------- + * Implementation of the store for non-persistent snapshots. + *--------------------------------------------------------------- + */ +struct transient_c { + sector_t next_free; +}; + +static void transient_dtr(struct dm_exception_store *store) +{ + kfree(store->context); +} + +static int transient_read_metadata(struct dm_exception_store *store, + int (*callback)(void *callback_context, + chunk_t old, chunk_t new), + void *callback_context) +{ + return 0; +} + +static int transient_prepare_exception(struct dm_exception_store *store, + struct dm_exception *e) +{ + struct transient_c *tc = store->context; + sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev); + + if (size < (tc->next_free + store->chunk_size)) + return -1; + + e->new_chunk = sector_to_chunk(store, tc->next_free); + tc->next_free += store->chunk_size; + + return 0; +} + +static void transient_commit_exception(struct dm_exception_store *store, + struct dm_exception *e, int valid, + void (*callback)(void *, int success), + void *callback_context) +{ + /* Just succeed */ + callback(callback_context, valid); +} + +static void transient_usage(struct dm_exception_store *store, + sector_t *total_sectors, + sector_t *sectors_allocated, + sector_t *metadata_sectors) +{ + *sectors_allocated = ((struct transient_c *) store->context)->next_free; + *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev); + *metadata_sectors = 0; +} + +static int transient_ctr(struct dm_exception_store *store, char *options) +{ + struct transient_c *tc; + + tc = kmalloc_obj(struct transient_c); + if (!tc) + return -ENOMEM; + + tc->next_free = 0; + store->context = tc; + + return 0; +} + +static unsigned int transient_status(struct dm_exception_store *store, + status_type_t status, char *result, + unsigned int maxlen) +{ + unsigned int sz = 0; + + switch (status) { + case STATUSTYPE_INFO: + break; + case STATUSTYPE_TABLE: + DMEMIT(" N %llu", (unsigned long long)store->chunk_size); + break; + case STATUSTYPE_IMA: + *result = '\0'; + break; + } + + return sz; +} + +static struct dm_exception_store_type _transient_type = { + .name = "transient", + .module = THIS_MODULE, + .ctr = transient_ctr, + .dtr = transient_dtr, + .read_metadata = transient_read_metadata, + .prepare_exception = transient_prepare_exception, + .commit_exception = transient_commit_exception, + .usage = transient_usage, + .status = transient_status, +}; + +static struct dm_exception_store_type _transient_compat_type = { + .name = "N", + .module = THIS_MODULE, + .ctr = transient_ctr, + .dtr = transient_dtr, + .read_metadata = transient_read_metadata, + .prepare_exception = transient_prepare_exception, + .commit_exception = transient_commit_exception, + .usage = transient_usage, + .status = transient_status, +}; + +int dm_transient_snapshot_init(void) +{ + int r; + + r = dm_exception_store_type_register(&_transient_type); + if (r) { + DMWARN("Unable to register transient exception store type"); + return r; + } + + r = dm_exception_store_type_register(&_transient_compat_type); + if (r) { + DMWARN("Unable to register old-style transient exception store type"); + dm_exception_store_type_unregister(&_transient_type); + return r; + } + + return r; +} + +void dm_transient_snapshot_exit(void) +{ + dm_exception_store_type_unregister(&_transient_type); + dm_exception_store_type_unregister(&_transient_compat_type); +} -- cgit v1.3.1