fasync_helper

函数名称：async_helper() is used by almost all character device drivers* to set up the fasync queue, and for regular files by the file* lease code. It returns negative on error, 0 if it did no changes* and positive if it added/deleted the entry.

函数原型：int fasync_helper(int fd, struct file *filp, int on, struct fasync_struct **fapp)

返回类型：int

参数：

类型	参数	名称
int	fd
struct file *	filp
int	on
struct fasync_struct **	fapp

980

如果非on则返回:Remove a fasync entry. If successfully removed, return* positive and clear the FASYNC flag. If no entry exists,* do nothing and return 0.* NOTE! It is very important that the FASYNC flag always* match the state "is the filp on a fasync list".

982

返回:Add a fasync entry. Return negative on error, positive if* added, and zero if did nothing but change an existing one.

**调用者**
名称	描述
pipe_fasync
fsnotify_fasync
io_uring_fasync
lease_modify	We already had a lease on this file; just change its type
perf_fasync

源代码转换工具开放的插件接口	X
支持：c/c++/esqlc/java Oracle/Informix/Mysql 插件可实现：逻辑报告代码生成和批量转换代码

函数逻辑报告