Add a helper that returns the file descriptor and ensures that the old
variable contains a negative value. This makes it easy to rely on
CLASS(get_unused_fd).
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
include/linux/cleanup.h | 13 ++++++++-----
include/linux/file.h | 2 ++
2 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index c2d09bc4f976..80c4181e194a 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -63,17 +63,20 @@
#define __free(_name) __cleanup(__free_##_name)
-#define __get_and_null_ptr(p) \
- ({ __auto_type __ptr = &(p); \
- __auto_type __val = *__ptr; \
- *__ptr = NULL; __val; })
+#define __get_and_null(p, nullvalue) \
+ ({ \
+ __auto_type __ptr = &(p); \
+ __auto_type __val = *__ptr; \
+ *__ptr = nullvalue; \
+ __val; \
+ })
static inline __must_check
const volatile void * __must_check_fn(const volatile void *val)
{ return val; }
#define no_free_ptr(p) \
- ((typeof(p)) __must_check_fn(__get_and_null_ptr(p)))
+ ((typeof(p)) __must_check_fn(__get_and_null(p, NULL)))
#define return_ptr(p) return no_free_ptr(p)
diff --git a/include/linux/file.h b/include/linux/file.h
index 45d0f4800abd..3ea7f2452f20 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -97,6 +97,8 @@ 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)
+#define take_fd(fd) __get_and_null(fd, -EBADF)
+
extern void fd_install(unsigned int fd, struct file *file);
int receive_fd(struct file *file, int __user *ufd, unsigned int o_flags);
--
2.43.0
