linuxkpi: Fix llist_entry

[manu]

Summary

llist_entry(NULL) must not return NULL, it needs to wrap around
and return NULL minus the offset.

the iterators stop when the offset added back to the result of
llist_entry() is NULL

they test that the first node is not NULL or that the next pointer
stored in a previous iteration of the loop is not NULL

OpenBSD commit: https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/sys/dev/pci/drm/include/linux/llist.h?rev=1.3&content-type=text/x-cvsweb-markup

Reported by: [e-mail]
Sponsored by: Beckhoff Automation GmbH & Co. KG

[• hselasky]

sys/compat/linuxkpi/common/include/linux/llist.h

91

Is it more clean to write:

(pos) != llist_entry(NULL, __typeof(*pos), member)

92

While at it change:

pos->member.next

into:

(pos)->member.next

97

Ditto?

[manu]

sys/compat/linuxkpi/common/include/linux/llist.h

91

Why that ?
I find your way more confusing.

[• hselasky]

sys/compat/linuxkpi/common/include/linux/llist.h

91

Because container_of() is doing some type checking at least, while (char *) is a pure cast.

I don't have any strong opinion here.