On Mon, Nov 29, 2021 at 07:35:54AM -1000, Tejun Heo wrote: >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. > That's interesting. Thanks. >Thanks. > >-- >tejun -- Wei Yang Help you, Help me
