From: Peter Zijlstra peterz@infradead.org

commit 54da6a0924311c7cf5015533991e44fb8eb12773 upstream.

Use __attribute__((__cleanup__(func))) to build:

- simple auto-release pointers using __free()

- 'classes' with constructor and destructor semantics for scope-based resource management.

- lock guards based on the above classes.

Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Lukas Wunner lukas@wunner.de Link: https://lkml.kernel.org/r/20230612093537.614161713%40infradead.org --- include/linux/cleanup.h | 171 ++++++++++++++++++++++++++++ include/linux/compiler-clang.h | 9 ++ include/linux/compiler_attributes.h | 6 + include/linux/device.h | 7 ++ include/linux/file.h | 6 + include/linux/irqflags.h | 7 ++ include/linux/mutex.h | 4 + include/linux/percpu.h | 4 + include/linux/preempt.h | 5 + include/linux/rcupdate.h | 3 + include/linux/rwsem.h | 9 ++ include/linux/sched/task.h | 2 + include/linux/slab.h | 3 + include/linux/spinlock.h | 31 +++++ include/linux/srcu.h | 5 + scripts/checkpatch.pl | 2 +- 16 files changed, 273 insertions(+), 1 deletion(-) create mode 100644 include/linux/cleanup.h

diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h new file mode 100644 index 000000000000..53f1a7a932b0 --- /dev/null +++ b/include/linux/cleanup.h @@ -0,0 +1,171 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __LINUX_GUARDS_H +#define __LINUX_GUARDS_H + +#include <linux/compiler.h> + +/* + * DEFINE_FREE(name, type, free): + * simple helper macro that defines the required wrapper for a __free() + * based cleanup function. @free is an expression using '_T' to access + * the variable. + * + * __free(name): + * variable attribute to add a scoped based cleanup to the variable. + * + * no_free_ptr(var): + * like a non-atomic xchg(var, NULL), such that the cleanup function will + * be inhibited -- provided it sanely deals with a NULL value. + * + * return_ptr(p): + * returns p while inhibiting the __free(). + * + * Ex. + * + * DEFINE_FREE(kfree, void *, if (_T) kfree(_T)) + * + * struct obj *p __free(kfree) = kmalloc(...); + * if (!p) + * return NULL; + * + * if (!init_obj(p)) + * return NULL; + * + * return_ptr(p); + */ + +#define DEFINE_FREE(_name, _type, _free) \ + static inline void __free_##_name(void *p) { _type _T = *(_type *)p; _free; } + +#define __free(_name) __cleanup(__free_##_name) + +#define no_free_ptr(p) \ + ({ __auto_type __ptr = (p); (p) = NULL; __ptr; }) + +#define return_ptr(p) return no_free_ptr(p) + + +/* + * DEFINE_CLASS(name, type, exit, init, init_args...): + * helper to define the destructor and constructor for a type. + * @exit is an expression using '_T' -- similar to FREE above. + * @init is an expression in @init_args resulting in @type + * + * EXTEND_CLASS(name, ext, init, init_args...): + * extends class @name to @name@ext with the new constructor + * + * CLASS(name, var)(args...): + * declare the variable @var as an instance of the named class + * + * Ex. + * + * DEFINE_CLASS(fdget, struct fd, fdput(_T), fdget(fd), int fd) + * + * CLASS(fdget, f)(fd); + * if (!f.file) + * return -EBADF; + * + * // use 'f' without concern + */ + +#define DEFINE_CLASS(_name, _type, _exit, _init, _init_args...) \ +typedef _type class_##_name##_t; \ +static inline void class_##_name##_destructor(_type *p) \ +{ _type _T = *p; _exit; } \ +static inline _type class_##_name##_constructor(_init_args) \ +{ _type t = _init; return t; } + +#define EXTEND_CLASS(_name, ext, _init, _init_args...) \ +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) \ +{ class_##_name##_t t = _init; return t; } + +#define CLASS(_name, var) \ + class_##_name##_t var __cleanup(class_##_name##_destructor) = \ + class_##_name##_constructor + + +/* + * DEFINE_GUARD(name, type, lock, unlock): + * trivial wrapper around DEFINE_CLASS() above specifically + * for locks. + * + * guard(name): + * an anonymous instance of the (guard) class + * + * scoped_guard (name, args...) { }: + * similar to CLASS(name, scope)(args), except the variable (with the + * explicit name 'scope') is declard in a for-loop such that its scope is + * bound to the next (compound) statement. + * + */ + +#define DEFINE_GUARD(_name, _type, _lock, _unlock) \ + DEFINE_CLASS(_name, _type, _unlock, ({ _lock; _T; }), _type _T) + +#define guard(_name) \ + CLASS(_name, __UNIQUE_ID(guard)) + +#define scoped_guard(_name, args...) \ + for (CLASS(_name, scope)(args), \ + *done = NULL; !done; done = (void *)1) + +/* + * Additional helper macros for generating lock guards with types, either for + * locks that don't have a native type (eg. RCU, preempt) or those that need a + * 'fat' pointer (eg. spin_lock_irqsave). + * + * DEFINE_LOCK_GUARD_0(name, lock, unlock, ...) + * DEFINE_LOCK_GUARD_1(name, type, lock, unlock, ...) + * + * will result in the following type: + * + * typedef struct { + * type *lock; // 'type := void' for the _0 variant + * __VA_ARGS__; + * } class_##name##_t; + * + * As above, both _lock and _unlock are statements, except this time '_T' will + * be a pointer to the above struct. + */ + +#define __DEFINE_UNLOCK_GUARD(_name, _type, _unlock, ...) \ +typedef struct { \ + _type *lock; \ + __VA_ARGS__; \ +} class_##_name##_t; \ + \ +static inline void class_##_name##_destructor(class_##_name##_t *_T) \ +{ \ + if (_T->lock) { _unlock; } \ +} + + +#define __DEFINE_LOCK_GUARD_1(_name, _type, _lock) \ +static inline class_##_name##_t class_##_name##_constructor(_type *l) \ +{ \ + class_##_name##_t _t = { .lock = l }, *_T = &_t; \ + _lock; \ + return _t; \ +} + +#define __DEFINE_LOCK_GUARD_0(_name, _lock) \ +static inline class_##_name##_t class_##_name##_constructor(void) \ +{ \ + class_##_name##_t _t = { .lock = (void*)1 }, \ + *_T __maybe_unused = &_t; \ + _lock; \ + return _t; \ +} + +#define DEFINE_LOCK_GUARD_1(_name, _type, _lock, _unlock, ...) \ +__DEFINE_UNLOCK_GUARD(_name, _type, _unlock, __VA_ARGS__) \ +__DEFINE_LOCK_GUARD_1(_name, _type, _lock) + +#define DEFINE_LOCK_GUARD_0(_name, _lock, _unlock, ...) \ +__DEFINE_UNLOCK_GUARD(_name, void, _unlock, __VA_ARGS__) \ +__DEFINE_LOCK_GUARD_0(_name, _lock) + +#endif /* __LINUX_GUARDS_H */ diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index 9ba951e3a6c2..d1f6f594c508 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -15,6 +15,15 @@

/* Compiler specific definitions for Clang compiler */

+/* + * Clang prior to 17 is being silly and considers many __cleanup() variables + * as unused (because they are, their sole purpose is to go out of scope). + * + * https://reviews.llvm.org/D152180 + */ +#undef __cleanup +#define __cleanup(func) __maybe_unused __attribute__((__cleanup__(func))) + /* same as gcc, this was present in clang-2.6 so we can assume it works * with any version that can compile the kernel */ diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index 3982c2dc541e..089fd96378a7 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -93,6 +93,12 @@ */ #define __cold __attribute__((__cold__))

+/* + * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-cle... + * clang: https://clang.llvm.org/docs/AttributeReference.html#cleanup + */ +#define __cleanup(func) __attribute__((__cleanup__(func))) + /* * Note the long name. * diff --git a/include/linux/device.h b/include/linux/device.h index 9c9ce573c737..fb15f50894fa 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -30,6 +30,7 @@ #include <linux/device/bus.h> #include <linux/device/class.h> #include <linux/device/driver.h> +#include <linux/cleanup.h> #include <asm/device.h>

struct device; @@ -826,6 +827,9 @@ void device_unregister(struct device *dev); void device_initialize(struct device *dev); int __must_check device_add(struct device *dev); void device_del(struct device *dev); + +DEFINE_FREE(device_del, struct device *, if (_T) device_del(_T)) + int device_for_each_child(struct device *dev, void *data, int (*fn)(struct device *dev, void *data)); int device_for_each_child_reverse(struct device *dev, void *data, @@ -952,6 +956,9 @@ extern int (*platform_notify_remove)(struct device *dev); */ struct device *get_device(struct device *dev); void put_device(struct device *dev); + +DEFINE_FREE(put_device, struct device *, if (_T) put_device(_T)) + bool kill_device(struct device *dev);

#ifdef CONFIG_DEVTMPFS diff --git a/include/linux/file.h b/include/linux/file.h index 225982792fa2..5b4e31388648 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -10,6 +10,7 @@ #include <linux/types.h> #include <linux/posix_types.h> #include <linux/errno.h> +#include <linux/cleanup.h>

struct file;

@@ -82,6 +83,8 @@ static inline void fdput_pos(struct fd f) fdput(f); }

+DEFINE_CLASS(fd, struct fd, fdput(_T), fdget(fd), int fd) + extern int f_dupfd(unsigned int from, struct file *file, unsigned flags); extern int replace_fd(unsigned fd, struct file *file, unsigned flags); extern void set_close_on_exec(unsigned int fd, int flag); @@ -90,6 +93,9 @@ extern int __get_unused_fd_flags(unsigned flags, unsigned long nofile); extern int get_unused_fd_flags(unsigned flags); extern void put_unused_fd(unsigned int fd);

+DEFINE_CLASS(get_unused_fd, int, if (_T >= 0) put_unused_fd(_T), + get_unused_fd_flags(flags), unsigned flags) + extern void fd_install(unsigned int fd, struct file *file);

extern int __receive_fd(int fd, struct file *file, int __user *ufd, diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h index a53adf4316a5..9beebc188fd4 100644 --- a/include/linux/irqflags.h +++ b/include/linux/irqflags.h @@ -13,6 +13,7 @@ #define _LINUX_TRACE_IRQFLAGS_H

#include <linux/typecheck.h> +#include <linux/cleanup.h> #include <asm/irqflags.h> #include <asm/percpu.h>

@@ -248,4 +249,10 @@ do { \

#define irqs_disabled_flags(flags) raw_irqs_disabled_flags(flags)

+DEFINE_LOCK_GUARD_0(irq, local_irq_disable(), local_irq_enable()) +DEFINE_LOCK_GUARD_0(irqsave, + local_irq_save(_T->flags), + local_irq_restore(_T->flags), + unsigned long flags) + #endif diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 4d671fba3cab..386f436e5148 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -19,6 +19,7 @@ #include <asm/processor.h> #include <linux/osq_lock.h> #include <linux/debug_locks.h> +#include <linux/cleanup.h>

struct ww_acquire_ctx;

@@ -199,6 +200,9 @@ extern void mutex_unlock(struct mutex *lock);

extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);

+DEFINE_GUARD(mutex, struct mutex *, mutex_lock(_T), mutex_unlock(_T)) +DEFINE_FREE(mutex, struct mutex *, if (_T) mutex_unlock(_T)) + /* * These values are chosen such that FAIL and SUCCESS match the * values of the regular mutex_trylock(). diff --git a/include/linux/percpu.h b/include/linux/percpu.h index 5e76af742c80..c9a84532bb79 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -9,6 +9,7 @@ #include <linux/printk.h> #include <linux/pfn.h> #include <linux/init.h> +#include <linux/cleanup.h>

#include <asm/percpu.h>

@@ -134,6 +135,9 @@ extern void __init setup_per_cpu_areas(void); extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp); extern void __percpu *__alloc_percpu(size_t size, size_t align); extern void free_percpu(void __percpu *__pdata); + +DEFINE_FREE(free_percpu, void __percpu *, free_percpu(_T)) + extern phys_addr_t per_cpu_ptr_to_phys(void *addr);

#define alloc_percpu_gfp(type, gfp) \ diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 7d9c1c0e149c..9a70e1e315d3 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -8,6 +8,7 @@ */

#include <linux/linkage.h> +#include <linux/cleanup.h> #include <linux/list.h>

/* @@ -352,4 +353,8 @@ static __always_inline void migrate_enable(void) preempt_enable(); }

+DEFINE_LOCK_GUARD_0(preempt, preempt_disable(), preempt_enable()) +DEFINE_LOCK_GUARD_0(preempt_notrace, preempt_disable_notrace(), preempt_enable_notrace()) +DEFINE_LOCK_GUARD_0(migrate, migrate_disable(), migrate_enable()) + #endif /* __LINUX_PREEMPT_H */ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 9db6710e6ee7..7c7c3fce6bb2 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -27,6 +27,7 @@ #include <linux/preempt.h> #include <linux/bottom_half.h> #include <linux/lockdep.h> +#include <linux/cleanup.h> #include <asm/processor.h> #include <linux/cpumask.h>

@@ -1055,4 +1056,6 @@ rcu_head_after_call_rcu(struct rcu_head *rhp, rcu_callback_t f) extern int rcu_expedited; extern int rcu_normal;

+DEFINE_LOCK_GUARD_0(rcu, rcu_read_lock(), rcu_read_unlock()) + #endif /* __LINUX_RCUPDATE_H */ diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index 4c715be48717..debdd9c3a5e5 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -16,6 +16,8 @@ #include <linux/spinlock.h> #include <linux/atomic.h> #include <linux/err.h> +#include <linux/cleanup.h> + #ifdef CONFIG_RWSEM_SPIN_ON_OWNER #include <linux/osq_lock.h> #endif @@ -152,6 +154,13 @@ extern void up_read(struct rw_semaphore *sem); */ extern void up_write(struct rw_semaphore *sem);

+DEFINE_GUARD(rwsem_read, struct rw_semaphore *, down_read(_T), up_read(_T)) +DEFINE_GUARD(rwsem_write, struct rw_semaphore *, down_write(_T), up_write(_T)) + +DEFINE_FREE(up_read, struct rw_semaphore *, if (_T) up_read(_T)) +DEFINE_FREE(up_write, struct rw_semaphore *, if (_T) up_write(_T)) + + /* * downgrade write lock to read lock */ diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index de21a45a4ee7..10545f5f6bb5 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -143,6 +143,8 @@ static inline void put_task_struct(struct task_struct *t) __put_task_struct(t); }

+DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T)) + static inline void put_task_struct_many(struct task_struct *t, int nr) { if (refcount_sub_and_test(nr, &t->usage)) diff --git a/include/linux/slab.h b/include/linux/slab.h index dd6897f62010..dac1c1decf76 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -17,6 +17,7 @@ #include <linux/types.h> #include <linux/workqueue.h> #include <linux/percpu-refcount.h> +#include <linux/cleanup.h>

/* @@ -187,6 +188,8 @@ void kfree_sensitive(const void *); size_t __ksize(const void *); size_t ksize(const void *);

+DEFINE_FREE(kfree, void *, if (_T) kfree(_T)) + #ifdef CONFIG_HAVE_HARDENED_USERCOPY_ALLOCATOR void __check_heap_object(const void *ptr, unsigned long n, struct page *page, bool to_user); diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 79897841a2cc..9aea8c4e2d7c 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -57,6 +57,7 @@ #include <linux/stringify.h> #include <linux/bottom_half.h> #include <linux/lockdep.h> +#include <linux/cleanup.h> #include <asm/barrier.h> #include <asm/mmiowb.h>

@@ -493,4 +494,34 @@ int __alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *lock_mask,

void free_bucket_spinlocks(spinlock_t *locks);

+DEFINE_LOCK_GUARD_1(raw_spinlock, raw_spinlock_t, + raw_spin_lock(_T->lock), + raw_spin_unlock(_T->lock)) + +DEFINE_LOCK_GUARD_1(raw_spinlock_nested, raw_spinlock_t, + raw_spin_lock_nested(_T->lock, SINGLE_DEPTH_NESTING), + raw_spin_unlock(_T->lock)) + +DEFINE_LOCK_GUARD_1(raw_spinlock_irq, raw_spinlock_t, + raw_spin_lock_irq(_T->lock), + raw_spin_unlock_irq(_T->lock)) + +DEFINE_LOCK_GUARD_1(raw_spinlock_irqsave, raw_spinlock_t, + raw_spin_lock_irqsave(_T->lock, _T->flags), + raw_spin_unlock_irqrestore(_T->lock, _T->flags), + unsigned long flags) + +DEFINE_LOCK_GUARD_1(spinlock, spinlock_t, + spin_lock(_T->lock), + spin_unlock(_T->lock)) + +DEFINE_LOCK_GUARD_1(spinlock_irq, spinlock_t, + spin_lock_irq(_T->lock), + spin_unlock_irq(_T->lock)) + +DEFINE_LOCK_GUARD_1(spinlock_irqsave, spinlock_t, + spin_lock_irqsave(_T->lock, _T->flags), + spin_unlock_irqrestore(_T->lock, _T->flags), + unsigned long flags) + #endif /* __LINUX_SPINLOCK_H */ diff --git a/include/linux/srcu.h b/include/linux/srcu.h index a0895bbf71ce..e35168e0b952 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -205,4 +205,9 @@ static inline void smp_mb__after_srcu_read_unlock(void) /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */ }

+DEFINE_LOCK_GUARD_1(srcu, struct srcu_struct, + _T->idx = srcu_read_lock(_T->lock), + srcu_read_unlock(_T->lock, _T->idx), + int idx) + #endif diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 0ad235ee96f9..9a1c5ac4ba07 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -4522,7 +4522,7 @@ sub process { if|for|while|switch|return|case| volatile|__volatile__| __attribute__|format|__extension__| - asm|__asm__)$/x) + asm|__asm__|scoped_guard)$/x) { # cpp #define statements have non-optional spaces, ie # if there is a space between the name and the open