list_entry(), page 21

logicman112 · March 18th, 2009, 01:11 AM

The explanation of list_entry() macro is not clear. What does it return?

wlm · March 19th, 2009, 03:56 AM

list_entry returns a pointer to the container data structure. In the
example on p. 21/22, this would be a pointer to struct task_struct.
Unfortunately, the pointer declaration is missing. Correctly, the example
statement should read

Code:

struct task_struct *tsk = list_entry(ptr, struct task_struct, run_list);

Here we assume that ptr points to a list_head instance embedded in
task_struct (this was indeed the case for the O(1) scheduler):

Code:

struct task_struct {
...
    struct list_head run_list;
...
}