diff options
Diffstat (limited to 'kernel/time/timer_migration.c')
| -rw-r--r-- | kernel/time/timer_migration.c | 33 |
1 files changed, 15 insertions, 18 deletions
diff --git a/kernel/time/timer_migration.c b/kernel/time/timer_migration.c index 84413114db..d91efe1dc3 100644 --- a/kernel/time/timer_migration.c +++ b/kernel/time/timer_migration.c @@ -507,7 +507,14 @@ static void walk_groups(up_f up, void *data, struct tmigr_cpu *tmc) * (get_next_timer_interrupt()) * @firstexp: Contains the first event expiry information when last * active CPU of hierarchy is on the way to idle to make - * sure CPU will be back in time. + * sure CPU will be back in time. It is updated in top + * level group only. Be aware, there could occur a new top + * level of the hierarchy between the 'top level call' in + * tmigr_update_events() and the check for the parent group + * in walk_groups(). Then @firstexp might contain a value + * != KTIME_MAX even if it was not the final top + * level. This is not a problem, as the worst outcome is a + * CPU which might wake up a little early. * @evt: Pointer to tmigr_event which needs to be queued (of idle * child group) * @childmask: childmask of child group @@ -649,7 +656,7 @@ static bool tmigr_active_up(struct tmigr_group *group, } while (!atomic_try_cmpxchg(&group->migr_state, &curstate.state, newstate.state)); - if ((walk_done == false) && group->parent) + if (walk_done == false) data->childmask = group->childmask; /* @@ -1317,20 +1324,9 @@ static bool tmigr_inactive_up(struct tmigr_group *group, /* Event Handling */ tmigr_update_events(group, child, data); - if (group->parent && (walk_done == false)) + if (walk_done == false) data->childmask = group->childmask; - /* - * data->firstexp was set by tmigr_update_events() and contains the - * expiry of the first global event which needs to be handled. It - * differs from KTIME_MAX if: - * - group is the top level group and - * - group is idle (which means CPU was the last active CPU in the - * hierarchy) and - * - there is a pending event in the hierarchy - */ - WARN_ON_ONCE(data->firstexp != KTIME_MAX && group->parent); - trace_tmigr_group_set_cpu_inactive(group, newstate, childmask); return walk_done; @@ -1552,10 +1548,11 @@ static void tmigr_connect_child_parent(struct tmigr_group *child, data.childmask = child->childmask; /* - * There is only one new level per time. When connecting the - * child and the parent and set the child active when the parent - * is inactive, the parent needs to be the uppermost - * level. Otherwise there went something wrong! + * There is only one new level per time (which is protected by + * tmigr_mutex). When connecting the child and the parent and + * set the child active when the parent is inactive, the parent + * needs to be the uppermost level. Otherwise there went + * something wrong! */ WARN_ON(!tmigr_active_up(parent, child, &data) && parent->parent); } |