CODEWITHSUNDEEP
clinuxlinux-kernelkernellinux-device-driver
shd
shd

Reputation: 1129

linux kernel list_head vs empty entry that contains list_head

I'm trying to understand how this list works, by looking at the macro expansion of list_for_each_entry, the condition to exit the for is 

&pos->list_member != head

but I see code that written like this and works fine, I don't understand why it works

struct entry {
    int some_var;
    struct list_head list;
};

struct global {
    struct list_head entries_list;
};

struct global Global;
INIT_LIST_HEAD(&global.entries_list)
entry = kmalloc(new_entry..)
list_add_tail(&entry,&Global.entries_list);
list_for_each_entry(entry,&Global.entries_list,list) {

}

So by the end of the for, I should expect &entry->list == &Global.entries_list? How is this possible?

Upvotes: 0

Views: 528

Answers (1)

Tsyvarev
Tsyvarev

Reputation: 66298

So by the end of the for, I should expect &entry->list == &Global.entries_list?

Yes.

How is this possible?

Condition above means that entry is fake: it is not an element in the list, but just a raw pointer, which satisfies to given condition.

Upvotes: 1

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