diff options
Diffstat (limited to 'include/linux/cleanup.h')
| -rw-r--r-- | include/linux/cleanup.h | 249 |
1 files changed, 208 insertions, 41 deletions
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h index ee2614adb785..b1b5698cbf1b 100644 --- a/include/linux/cleanup.h +++ b/include/linux/cleanup.h @@ -3,6 +3,8 @@ #define _LINUX_CLEANUP_H #include <linux/compiler.h> +#include <linux/err.h> +#include <linux/args.h> /** * DOC: scope-based cleanup helpers @@ -61,9 +63,20 @@ * Observe the lock is held for the remainder of the "if ()" block not * the remainder of "func()". * - * Now, when a function uses both __free() and guard(), or multiple - * instances of __free(), the LIFO order of variable definition order - * matters. GCC documentation says: + * The ACQUIRE() macro can be used in all places that guard() can be + * used and additionally support conditional locks:: + * + * DEFINE_GUARD_COND(pci_dev, _try, pci_dev_trylock(_T)) + * ... + * ACQUIRE(pci_dev_try, lock)(dev); + * rc = ACQUIRE_ERR(pci_dev_try, &lock); + * if (rc) + * return rc; + * // @lock is held + * + * Now, when a function uses both __free() and guard()/ACQUIRE(), or + * multiple instances of __free(), the LIFO order of variable definition + * order matters. GCC documentation says: * * "When multiple variables in the same scope have cleanup attributes, * at exit from the scope their associated cleanup functions are run in @@ -195,19 +208,19 @@ */ #define DEFINE_FREE(_name, _type, _free) \ - static inline void __free_##_name(void *p) { _type _T = *(_type *)p; _free; } + static __always_inline void __free_##_name(void *p) { _type _T = *(_type *)p; _free; } #define __free(_name) __cleanup(__free_##_name) -#define __get_and_null(p, nullvalue) \ +#define __get_and_null(p, nullvalue) \ ({ \ - __auto_type __ptr = &(p); \ - __auto_type __val = *__ptr; \ + auto __ptr = &(p); \ + auto __val = *__ptr; \ *__ptr = nullvalue; \ __val; \ }) -static inline __must_check +static __always_inline __must_check const volatile void * __must_check_fn(const volatile void *val) { return val; } @@ -216,6 +229,25 @@ const volatile void * __must_check_fn(const volatile void *val) #define return_ptr(p) return no_free_ptr(p) +/* + * Only for situations where an allocation is handed in to another function + * and consumed by that function on success. + * + * struct foo *f __free(kfree) = kzalloc(sizeof(*f), GFP_KERNEL); + * + * setup(f); + * if (some_condition) + * return -EINVAL; + * .... + * ret = bar(f); + * if (!ret) + * retain_and_null_ptr(f); + * return ret; + * + * After retain_and_null_ptr(f) the variable f is NULL and cannot be + * dereferenced anymore. + */ +#define retain_and_null_ptr(p) ((void)__get_and_null(p, NULL)) /* * DEFINE_CLASS(name, type, exit, init, init_args...): @@ -229,6 +261,10 @@ const volatile void * __must_check_fn(const volatile void *val) * CLASS(name, var)(args...): * declare the variable @var as an instance of the named class * + * CLASS_INIT(name, var, init_expr): + * declare the variable @var as an instance of the named class with + * custom initialization expression. + * * Ex. * * DEFINE_CLASS(fdget, struct fd, fdput(_T), fdget(fd), int fd) @@ -242,22 +278,42 @@ const volatile void * __must_check_fn(const volatile void *val) #define DEFINE_CLASS(_name, _type, _exit, _init, _init_args...) \ typedef _type class_##_name##_t; \ -static inline void class_##_name##_destructor(_type *p) \ +typedef _type lock_##_name##_t; \ +static __always_inline void class_##_name##_destructor(_type *p) \ + __no_context_analysis \ { _type _T = *p; _exit; } \ -static inline _type class_##_name##_constructor(_init_args) \ +static __always_inline _type class_##_name##_constructor(_init_args) \ + __no_context_analysis \ { _type t = _init; return t; } -#define EXTEND_CLASS(_name, ext, _init, _init_args...) \ +#define EXTEND_CLASS_COND(_name, ext, _cond, _init, _init_args...) \ +typedef lock_##_name##_t lock_##_name##ext##_t; \ typedef class_##_name##_t class_##_name##ext##_t; \ -static inline void class_##_name##ext##_destructor(class_##_name##_t *p)\ -{ class_##_name##_destructor(p); } \ -static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \ +static __always_inline void class_##_name##ext##_destructor(class_##_name##_t *_T) \ +{ if (_cond) return; class_##_name##_destructor(_T); } \ +static __always_inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \ + __no_context_analysis \ { class_##_name##_t t = _init; return t; } +#define EXTEND_CLASS(_name, ext, _init, _init_args...) \ + EXTEND_CLASS_COND(_name, ext, 0, _init, _init_args) + #define CLASS(_name, var) \ class_##_name##_t var __cleanup(class_##_name##_destructor) = \ class_##_name##_constructor +#define CLASS_INIT(_name, _var, _init_expr) \ + class_##_name##_t _var __cleanup(class_##_name##_destructor) = (_init_expr) + +#define __scoped_class(_name, var, _label, args...) \ + for (CLASS(_name, var)(args); ; ({ goto _label; })) \ + if (0) { \ +_label: \ + break; \ + } else + +#define scoped_class(_name, var, args...) \ + __scoped_class(_name, var, __UNIQUE_ID(label), args) /* * DEFINE_GUARD(name, type, lock, unlock): @@ -286,31 +342,93 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \ * acquire fails. * * Only for conditional locks. + * + * ACQUIRE(name, var): + * a named instance of the (guard) class, suitable for conditional + * locks when paired with ACQUIRE_ERR(). + * + * ACQUIRE_ERR(name, &var): + * a helper that is effectively a PTR_ERR() conversion of the guard + * pointer. Returns 0 when the lock was acquired and a negative + * error code otherwise. */ #define __DEFINE_CLASS_IS_CONDITIONAL(_name, _is_cond) \ static __maybe_unused const bool class_##_name##_is_conditional = _is_cond -#define DEFINE_GUARD(_name, _type, _lock, _unlock) \ - __DEFINE_CLASS_IS_CONDITIONAL(_name, false); \ - DEFINE_CLASS(_name, _type, if (_T) { _unlock; }, ({ _lock; _T; }), _type _T); \ +#define DEFINE_CLASS_IS_UNCONDITIONAL(_name) \ + __DEFINE_CLASS_IS_CONDITIONAL(_name, false); \ static inline void * class_##_name##_lock_ptr(class_##_name##_t *_T) \ - { return (void *)(__force unsigned long)*_T; } + { return (void *)1; } + +#define __GUARD_IS_ERR(_ptr) \ + ({ \ + unsigned long _rc = (__force unsigned long)(_ptr); \ + unlikely((_rc - 1) >= -MAX_ERRNO - 1); \ + }) + +#define __DEFINE_GUARD_LOCK_PTR(_name, _exp) \ + static __always_inline void *class_##_name##_lock_ptr(class_##_name##_t *_T) \ + { \ + void *_ptr = (void *)(__force unsigned long)*(_exp); \ + if (IS_ERR(_ptr)) { \ + _ptr = NULL; \ + } \ + return _ptr; \ + } \ + static __always_inline int class_##_name##_lock_err(class_##_name##_t *_T) \ + { \ + long _rc = (__force unsigned long)*(_exp); \ + if (!_rc) { \ + _rc = -EBUSY; \ + } \ + if (!IS_ERR_VALUE(_rc)) { \ + _rc = 0; \ + } \ + return _rc; \ + } + +#define DEFINE_CLASS_IS_GUARD(_name) \ + __DEFINE_CLASS_IS_CONDITIONAL(_name, false); \ + __DEFINE_GUARD_LOCK_PTR(_name, _T) + +#define DEFINE_CLASS_IS_COND_GUARD(_name) \ + __DEFINE_CLASS_IS_CONDITIONAL(_name, true); \ + __DEFINE_GUARD_LOCK_PTR(_name, _T) -#define DEFINE_GUARD_COND(_name, _ext, _condlock) \ +#define DEFINE_GUARD(_name, _type, _lock, _unlock) \ + static __always_inline __nonnull_args(1) _type class_##_name##_constructor(_type _T); \ + DEFINE_CLASS(_name, _type, _unlock, ({ _lock; _T; }), _type _T); \ + DEFINE_CLASS_IS_GUARD(_name) + +#define DEFINE_GUARD_COND_4(_name, _ext, _lock, _cond) \ __DEFINE_CLASS_IS_CONDITIONAL(_name##_ext, true); \ - EXTEND_CLASS(_name, _ext, \ - ({ void *_t = _T; if (_T && !(_condlock)) _t = NULL; _t; }), \ + EXTEND_CLASS_COND(_name, _ext, __GUARD_IS_ERR(*_T), \ + ({ void *_t = _T; int _RET = (_lock); if (_T && !(_cond)) _t = ERR_PTR(_RET); _t; }), \ class_##_name##_t _T) \ - static inline void * class_##_name##_ext##_lock_ptr(class_##_name##_t *_T) \ - { return class_##_name##_lock_ptr(_T); } + static __always_inline void * class_##_name##_ext##_lock_ptr(class_##_name##_t *_T) \ + { return class_##_name##_lock_ptr(_T); } \ + static __always_inline int class_##_name##_ext##_lock_err(class_##_name##_t *_T) \ + { return class_##_name##_lock_err(_T); } + +/* + * Default binary condition; success on 'true'. + */ +#define DEFINE_GUARD_COND_3(_name, _ext, _lock) \ + DEFINE_GUARD_COND_4(_name, _ext, _lock, _RET) + +#define DEFINE_GUARD_COND(X...) CONCATENATE(DEFINE_GUARD_COND_, COUNT_ARGS(X))(X) #define guard(_name) \ CLASS(_name, __UNIQUE_ID(guard)) #define __guard_ptr(_name) class_##_name##_lock_ptr +#define __guard_err(_name) class_##_name##_lock_err #define __is_cond_ptr(_name) class_##_name##_is_conditional +#define ACQUIRE(_name, _var) CLASS(_name, _var) +#define ACQUIRE_ERR(_name, _var) __guard_err(_name)(_var) + /* * Helper macro for scoped_guard(). * @@ -365,39 +483,81 @@ _label: \ */ #define __DEFINE_UNLOCK_GUARD(_name, _type, _unlock, ...) \ +typedef _type lock_##_name##_t; \ typedef struct { \ _type *lock; \ __VA_ARGS__; \ } class_##_name##_t; \ \ -static inline void class_##_name##_destructor(class_##_name##_t *_T) \ +static __always_inline void class_##_name##_destructor(class_##_name##_t *_T) \ + __no_context_analysis \ { \ - if (_T->lock) { _unlock; } \ + _unlock; \ } \ \ -static inline void *class_##_name##_lock_ptr(class_##_name##_t *_T) \ -{ \ - return (void *)(__force unsigned long)_T->lock; \ -} - +__DEFINE_GUARD_LOCK_PTR(_name, &_T->lock) -#define __DEFINE_LOCK_GUARD_1(_name, _type, _lock) \ -static inline class_##_name##_t class_##_name##_constructor(_type *l) \ +#define __DEFINE_LOCK_GUARD_1(_name, _type, ...) \ +static __always_inline __nonnull_args(1) \ +class_##_name##_t class_##_name##_constructor(_type *l) \ + __no_context_analysis \ { \ class_##_name##_t _t = { .lock = l }, *_T = &_t; \ - _lock; \ + __VA_ARGS__; \ return _t; \ } -#define __DEFINE_LOCK_GUARD_0(_name, _lock) \ -static inline class_##_name##_t class_##_name##_constructor(void) \ +#define __DEFINE_LOCK_GUARD_0(_name, ...) \ +static __always_inline class_##_name##_t class_##_name##_constructor(void) \ + __no_context_analysis \ { \ class_##_name##_t _t = { .lock = (void*)1 }, \ *_T __maybe_unused = &_t; \ - _lock; \ + __VA_ARGS__; \ return _t; \ } +#define DECLARE_LOCK_GUARD_0_ATTRS(_name, _lock, _unlock) \ +static inline class_##_name##_t class_##_name##_constructor(void) _lock;\ +static inline void class_##_name##_destructor(class_##_name##_t *_T) _unlock; + +/* + * To support Context Analysis, we need to allow the compiler to see the + * acquisition and release of the context lock. However, the "cleanup" helpers + * wrap the lock in a struct passed through separate helper functions, which + * hides the lock alias from the compiler (no inter-procedural analysis). + * + * To make it work, we introduce an explicit alias to the context lock instance + * that is "cleaned" up with a separate cleanup helper. This helper is a dummy + * function that does nothing at runtime, but has the "_unlock" attribute to + * tell the compiler what happens at the end of the scope. + * + * To generalize the pattern, the WITH_LOCK_GUARD_1_ATTRS() macro should be used + * to redefine the constructor, which then also creates the alias variable with + * the right "cleanup" attribute, *after* DECLARE_LOCK_GUARD_1_ATTRS() has been + * used. + * + * Example usage: + * + * DECLARE_LOCK_GUARD_1_ATTRS(mutex, __acquires(_T), __releases(*(struct mutex **)_T)) + * #define class_mutex_constructor(_T) WITH_LOCK_GUARD_1_ATTRS(mutex, _T) + * + * Note: To support the for-loop based scoped helpers, the auxiliary variable + * must be a pointer to the "class" type because it is defined in the same + * statement as the guard variable. However, we initialize it with the lock + * pointer (despite the type mismatch, the compiler's alias analysis still works + * as expected). The "_unlock" attribute receives a pointer to the auxiliary + * variable (a double pointer to the class type), and must be cast and + * dereferenced appropriately. + */ +#define DECLARE_LOCK_GUARD_1_ATTRS(_name, _lock, _unlock) \ +static inline class_##_name##_t class_##_name##_constructor(lock_##_name##_t *_T) _lock;\ +static __always_inline void __class_##_name##_cleanup_ctx(class_##_name##_t **_T) \ + __no_context_analysis _unlock { } +#define WITH_LOCK_GUARD_1_ATTRS(_name, _T) \ + class_##_name##_constructor(_T), \ + *__UNIQUE_ID(unlock) __cleanup(__class_##_name##_cleanup_ctx) = (void *)(unsigned long)(_T) + #define DEFINE_LOCK_GUARD_1(_name, _type, _lock, _unlock, ...) \ __DEFINE_CLASS_IS_CONDITIONAL(_name, false); \ __DEFINE_UNLOCK_GUARD(_name, _type, _unlock, __VA_ARGS__) \ @@ -408,15 +568,22 @@ __DEFINE_CLASS_IS_CONDITIONAL(_name, false); \ __DEFINE_UNLOCK_GUARD(_name, void, _unlock, __VA_ARGS__) \ __DEFINE_LOCK_GUARD_0(_name, _lock) -#define DEFINE_LOCK_GUARD_1_COND(_name, _ext, _condlock) \ +#define DEFINE_LOCK_GUARD_1_COND_4(_name, _ext, _lock, _cond) \ __DEFINE_CLASS_IS_CONDITIONAL(_name##_ext, true); \ - EXTEND_CLASS(_name, _ext, \ + EXTEND_CLASS_COND(_name, _ext, __GUARD_IS_ERR(_T->lock), \ ({ class_##_name##_t _t = { .lock = l }, *_T = &_t;\ - if (_T->lock && !(_condlock)) _T->lock = NULL; \ + int _RET = (_lock); \ + if (_T->lock && !(_cond)) _T->lock = ERR_PTR(_RET);\ _t; }), \ typeof_member(class_##_name##_t, lock) l) \ - static inline void * class_##_name##_ext##_lock_ptr(class_##_name##_t *_T) \ - { return class_##_name##_lock_ptr(_T); } + static __always_inline void * class_##_name##_ext##_lock_ptr(class_##_name##_t *_T) \ + { return class_##_name##_lock_ptr(_T); } \ + static __always_inline int class_##_name##_ext##_lock_err(class_##_name##_t *_T) \ + { return class_##_name##_lock_err(_T); } + +#define DEFINE_LOCK_GUARD_1_COND_3(_name, _ext, _lock) \ + DEFINE_LOCK_GUARD_1_COND_4(_name, _ext, _lock, _RET) +#define DEFINE_LOCK_GUARD_1_COND(X...) CONCATENATE(DEFINE_LOCK_GUARD_1_COND_, COUNT_ARGS(X))(X) #endif /* _LINUX_CLEANUP_H */ |