函数逻辑报告

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:fs\notify\fanotify\fanotify_user.c Create Date:2022-07-29 10:50:16
Last Modify:2020-03-12 14:18:49 Copyright©Brick
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函数名称：fanotify_read

函数原型：static ssize_t fanotify_read(struct file *file, char __user *buf, size_t count, loff_t *pos)

返回类型：ssize_t

参数：

类型参数名称
struct file *file
char __user *buf
size_tcount
loff_t *pos
339  __user乘start
343  start等于buf
344  group等于 needed for tty driver, and maybe others
346  pr_debug("%s: group=%p\n", __func__, group)
348  add_wait_queue( & read() on the notification file blocks on this waitq , & wait)
349  当1循环
350  kevent等于Get an fsnotify notification event if one exists and is small* enough to fit in "count". Return an error pointer if the count* is not large enough. When permission event is dequeued, its state is* updated accordingly.
351  如果是错误则
352  ret等于错误
353  退出
356  如果非kevent则
357  ret等于负EAGAIN
358  如果f_flags按位与O_NONBLOCK则退出
361  ret等于负These should never be seen by user programs. To return one of ERESTART** codes, signal_pending() MUST be set. Note that ptrace can observe these* at syscall exit tracing, but they will never be left for the debugged user* process to see.
362  如果signal_pending(当前进程)则退出
365  如果start不等于buf则退出
368  DEFINE_WAIT_FUNC(wait, woken_wake_func);* add_wait_queue(&wq_head, &wait);* for (;;) {* if (condition)* break;* // in wait_woken() // in woken_wake_function()* p->state = mode; wq_entry->flags |= WQ_FLAG_WOKEN;* smp_mb(); // A try_to_wake_up():* if
369  继续下一循环
372  ret等于Copy an event to user space, returning how much we copied.* We already checked that the event size is smaller than the* buffer we had in "get_one_event()" above.
373  如果此条件成立可能性小(为编译器优化)(ret == - pen found a stale dentry )则
380  ret等于0
387  如果非fanotify_is_perm_event(mask)则
388  fsnotify_destroy_event(group, kevent)
389  否则
390  如果ret小于等于0则
395  否则
402  如果ret小于0则退出
404  buf加等于ret
405  count减等于ret
407  remove_wait_queue( & read() on the notification file blocks on this waitq , & wait)
409  如果start不等于buf且ret不等于负EFAULT则ret等于buf减start
411  返回:ret