[PATCH v5 3/8] cleanup.h: Introduce DEFINE_INACTIVE_GUARD and activate_guard
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: 2024-06-27 15:23:10
Also in:
bpf, lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
To cover scenarios where the scope of the guard differs from the scope
of its activation, introduce DEFINE_INACTIVE_GUARD() and activate_guard().
Here is an example use for a conditionally activated guard variable:
void func(bool a)
{
DEFINE_INACTIVE_GUARD(preempt_notrace, myguard);
[...]
if (a) {
might_sleep();
activate_guard(preempt_notrace, myguard)();
}
[ protected code ]
}
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kees Cook <redacted>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Sean Christopherson <seanjc@google.com>
---
include/linux/cleanup.h | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index 04f03ad5f25d..d6a3d8099d77 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h@@ -146,12 +146,20 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \ * similar to scoped_guard(), except it does fail when the lock * acquire fails. * + * DEFINE_INACTIVE_GUARD(name, var): + * define an inactive guard variable in a given scope, initialized to NULL. + * + * activate_guard(name, var)(args...): + * activate a guard variable with its constructor, if it is not already + * activated. */ #define DECLARE_GUARD(_name, _type, _lock, _unlock) \ DECLARE_CLASS(_name, _type, if (_T) { _unlock; }, ({ _lock; _T; }), _type _T); \ static inline void * class_##_name##_lock_ptr(class_##_name##_t *_T) \ - { return *_T; } + { return *_T; } \ + static inline class_##_name##_t class_##_name##_null(void) \ + { return NULL; } #define DECLARE_GUARD_COND(_name, _ext, _condlock) \ EXTEND_CLASS(_name, _ext, \
@@ -175,6 +183,14 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \ if (!__guard_ptr(_name)(&scope)) _fail; \ else +#define DEFINE_INACTIVE_GUARD(_name, _var) \ + class_##_name##_t _var __cleanup(class_##_name##_destructor) = \ + class_##_name##_null() + +#define activate_guard(_name, _var) \ + if (!class_##_name##_lock_ptr(&(_var))) \ + _var = class_##_name##_constructor + /* * 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
@@ -209,6 +225,11 @@ static inline void class_##_name##_destructor(class_##_name##_t *_T) \ static inline void *class_##_name##_lock_ptr(class_##_name##_t *_T) \ { \ return _T->lock; \ +} \ +static inline class_##_name##_t class_##_name##_null(void) \ +{ \ + class_##_name##_t _t = { .lock = NULL }; \ + return _t; \ }
--
2.39.2