c - 如何理解void (*action)(struct softirq_action *)

Question

这是Linux内核中的软中断。如何理解void (*action)(struct softirq_action *);的定义？

struct softirq_action
{
    void (*action)(struct softirq_action *);
};

Answer 1

从最左边的标识符开始，然后逐步解决，记住以下规则:

T *a[N];   // a is an array of pointer to T
T (*a)[N]; // a is a pointer to an array of T
T *f();    // f is a function returning a pointer to T
T (*f)();  // f is a pointer to a function returning T

所以:

       action                                -- action
      *action                                -- is a pointer to
     (*action)(                       )      -- a function taking
     (*action)(                       )      --   unnamed parameter
     (*action)(                      *)      --   is a pointer to
     (*action)(struct softirq_action *)      --   struct softirq_action
void (*action)(struct softirq_action *);     -- and returning void