On Sat, Nov 27, 2021 at 02:59:18PM +0000, Wei Yang wrote: > When the check, (ssid) < CGROUP_SUBSYS_COUNT, passed, it means > cgroup_subsys[ssid] is defined to its proper value. It is not > necessary to use a true to enter the loop. ... > #define for_each_subsys(ss, ssid) \ > for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ > - (((ss) = cgroup_subsys[ssid]) || true); (ssid)++) > + ((ss) = cgroup_subsys[ssid]); (ssid)++) So, now the compiler has to test whether ss is NULL or not before each iteration even though we know that it's never NULL. The whole point of that "|| true" is telling the compiler that the pointer is never NULL. Thanks. -- tejun
