You can then use the return pointer to configure other aspects of the virtual file, such as the function to call when a read is performed on the file.
然后就可以使用这个返回的指针来配置这个虚拟文件的其他参数，例如在对该文件执行读操作时应该调用的函数。
You use the access_ok function to check the validity of the pointer in user space that you intend to access.
您可以使用 access_ok 函数在您想要访问的用户空间检查指针的有效性。
Listing 8 is slightly more complex than the previous example because of the sigset function, which assigns a function pointer to a signal handler.
由于使用了sigset函数(它向信号处理程序分配一个函数指针)，清单8比前一个示例稍微复杂一点，。
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