diff options
Diffstat (limited to 'kernel/time/timer_migration.c')
| -rw-r--r-- | kernel/time/timer_migration.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/kernel/time/timer_migration.c b/kernel/time/timer_migration.c index 371a62a749aa..066c9ddca4ec 100644 --- a/kernel/time/timer_migration.c +++ b/kernel/time/timer_migration.c @@ -569,7 +569,7 @@ static struct tmigr_event *tmigr_next_groupevt(struct tmigr_group *group) while ((node = timerqueue_getnext(&group->events))) { evt = container_of(node, struct tmigr_event, nextevt); - if (!evt->ignore) { + if (!READ_ONCE(evt->ignore)) { WRITE_ONCE(group->next_expiry, evt->nextevt.expires); return evt; } @@ -665,7 +665,7 @@ static bool tmigr_active_up(struct tmigr_group *group, * lock is held while updating the ignore flag in idle path. So this * state change will not be lost. */ - group->groupevt.ignore = true; + WRITE_ONCE(group->groupevt.ignore, true); return walk_done; } @@ -726,6 +726,7 @@ bool tmigr_update_events(struct tmigr_group *group, struct tmigr_group *child, union tmigr_state childstate, groupstate; bool remote = data->remote; bool walk_done = false; + bool ignore; u64 nextexp; if (child) { @@ -744,11 +745,19 @@ bool tmigr_update_events(struct tmigr_group *group, struct tmigr_group *child, nextexp = child->next_expiry; evt = &child->groupevt; - evt->ignore = (nextexp == KTIME_MAX) ? true : false; + /* + * This can race with concurrent idle exit (activate). + * If the current writer wins, a useless remote expiration may + * be scheduled. If the activate wins, the event is properly + * ignored. + */ + ignore = (nextexp == KTIME_MAX) ? true : false; + WRITE_ONCE(evt->ignore, ignore); } else { nextexp = data->nextexp; first_childevt = evt = data->evt; + ignore = evt->ignore; /* * Walking the hierarchy is required in any case when a @@ -774,7 +783,7 @@ bool tmigr_update_events(struct tmigr_group *group, struct tmigr_group *child, * first event information of the group is updated properly and * also handled properly, so skip this fast return path. */ - if (evt->ignore && !remote && group->parent) + if (ignore && !remote && group->parent) return true; raw_spin_lock(&group->lock); @@ -788,7 +797,7 @@ bool tmigr_update_events(struct tmigr_group *group, struct tmigr_group *child, * queue when the expiry time changed only or when it could be ignored. */ if (timerqueue_node_queued(&evt->nextevt)) { - if ((evt->nextevt.expires == nextexp) && !evt->ignore) { + if ((evt->nextevt.expires == nextexp) && !ignore) { /* Make sure not to miss a new CPU event with the same expiry */ evt->cpu = first_childevt->cpu; goto check_toplvl; @@ -798,7 +807,7 @@ bool tmigr_update_events(struct tmigr_group *group, struct tmigr_group *child, WRITE_ONCE(group->next_expiry, KTIME_MAX); } - if (evt->ignore) { + if (ignore) { /* * When the next child event could be ignored (nextexp is * KTIME_MAX) and there was no remote timer handling before or |