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-cache-policy.c | 174 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 174 insertions(+) create mode 100644 drivers/md/dm-cache-policy.c (limited to 'drivers/md/dm-cache-policy.c') diff --git a/drivers/md/dm-cache-policy.c b/drivers/md/dm-cache-policy.c new file mode 100644 index 000000000..9330d5748 --- /dev/null +++ b/drivers/md/dm-cache-policy.c @@ -0,0 +1,174 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2012 Red Hat. All rights reserved. + * + * This file is released under the GPL. + */ + +#include "dm-cache-policy-internal.h" +#include "dm.h" + +#include +#include + +/*----------------------------------------------------------------*/ + +#define DM_MSG_PREFIX "cache-policy" + +static DEFINE_SPINLOCK(register_lock); +static LIST_HEAD(register_list); + +static struct dm_cache_policy_type *__find_policy(const char *name) +{ + struct dm_cache_policy_type *t; + + list_for_each_entry(t, ®ister_list, list) + if (!strcmp(t->name, name)) + return t; + + return NULL; +} + +static struct dm_cache_policy_type *__get_policy_once(const char *name) +{ + struct dm_cache_policy_type *t = __find_policy(name); + + if (t && !try_module_get(t->owner)) { + DMWARN("couldn't get module %s", name); + t = ERR_PTR(-EINVAL); + } + + return t; +} + +static struct dm_cache_policy_type *get_policy_once(const char *name) +{ + struct dm_cache_policy_type *t; + + spin_lock(®ister_lock); + t = __get_policy_once(name); + spin_unlock(®ister_lock); + + return t; +} + +static struct dm_cache_policy_type *get_policy(const char *name) +{ + struct dm_cache_policy_type *t; + + t = get_policy_once(name); + if (IS_ERR(t)) + return NULL; + + if (t) + return t; + + request_module("dm-cache-%s", name); + + t = get_policy_once(name); + if (IS_ERR(t)) + return NULL; + + return t; +} + +static void put_policy(struct dm_cache_policy_type *t) +{ + module_put(t->owner); +} + +int dm_cache_policy_register(struct dm_cache_policy_type *type) +{ + int r; + + /* One size fits all for now */ + if (type->hint_size != 0 && type->hint_size != 4) { + DMWARN("hint size must be 0 or 4 but %llu supplied.", (unsigned long long) type->hint_size); + return -EINVAL; + } + + spin_lock(®ister_lock); + if (__find_policy(type->name)) { + DMWARN("attempt to register policy under duplicate name %s", type->name); + r = -EINVAL; + } else { + list_add(&type->list, ®ister_list); + r = 0; + } + spin_unlock(®ister_lock); + + return r; +} +EXPORT_SYMBOL_GPL(dm_cache_policy_register); + +void dm_cache_policy_unregister(struct dm_cache_policy_type *type) +{ + spin_lock(®ister_lock); + list_del_init(&type->list); + spin_unlock(®ister_lock); +} +EXPORT_SYMBOL_GPL(dm_cache_policy_unregister); + +struct dm_cache_policy *dm_cache_policy_create(const char *name, + dm_cblock_t cache_size, + sector_t origin_size, + sector_t cache_block_size) +{ + struct dm_cache_policy *p = NULL; + struct dm_cache_policy_type *type; + + type = get_policy(name); + if (!type) { + DMWARN("unknown policy type"); + return ERR_PTR(-EINVAL); + } + + p = type->create(cache_size, origin_size, cache_block_size); + if (!p) { + put_policy(type); + return ERR_PTR(-ENOMEM); + } + p->private = type; + + return p; +} +EXPORT_SYMBOL_GPL(dm_cache_policy_create); + +void dm_cache_policy_destroy(struct dm_cache_policy *p) +{ + struct dm_cache_policy_type *t = p->private; + + p->destroy(p); + put_policy(t); +} +EXPORT_SYMBOL_GPL(dm_cache_policy_destroy); + +const char *dm_cache_policy_get_name(struct dm_cache_policy *p) +{ + struct dm_cache_policy_type *t = p->private; + + /* if t->real is set then an alias was used (e.g. "default") */ + if (t->real) + return t->real->name; + + return t->name; +} +EXPORT_SYMBOL_GPL(dm_cache_policy_get_name); + +const unsigned int *dm_cache_policy_get_version(struct dm_cache_policy *p) +{ + struct dm_cache_policy_type *t = p->private; + + return t->version; +} +EXPORT_SYMBOL_GPL(dm_cache_policy_get_version); + +size_t dm_cache_policy_get_hint_size(struct dm_cache_policy *p) +{ + struct dm_cache_policy_type *t = p->private; + + return t->hint_size; +} +EXPORT_SYMBOL_GPL(dm_cache_policy_get_hint_size); + +/*----------------------------------------------------------------*/ -- cgit v1.3.1