From: Ingo Molnar Date: Tue, 4 Dec 2007 16:04:39 +0000 (+0100) Subject: sched: fix crash in sys_sched_rr_get_interval() X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=77034937dc45;p=linux-beck.git sched: fix crash in sys_sched_rr_get_interval() Luiz Fernando N. Capitulino reported that sched_rr_get_interval() crashes for SCHED_OTHER tasks that are on an idle runqueue. The fix is to return a 0 timeslice for tasks that are on an idle runqueue. (and which are not running, obviously) this also shrinks the code a bit: text data bss dec hex filename 47903 3934 336 52173 cbcd sched.o.before 47885 3934 336 52155 cbbb sched.o.after Reported-by: Luiz Fernando N. Capitulino Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched.c b/kernel/sched.c index 59ff6b140edb..b062856b946c 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4850,17 +4850,21 @@ long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval) if (retval) goto out_unlock; - if (p->policy == SCHED_FIFO) - time_slice = 0; - else if (p->policy == SCHED_RR) + /* + * Time slice is 0 for SCHED_FIFO tasks and for SCHED_OTHER + * tasks that are on an otherwise idle runqueue: + */ + time_slice = 0; + if (p->policy == SCHED_RR) { time_slice = DEF_TIMESLICE; - else { + } else { struct sched_entity *se = &p->se; unsigned long flags; struct rq *rq; rq = task_rq_lock(p, &flags); - time_slice = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se)); + if (rq->cfs.load.weight) + time_slice = NS_TO_JIFFIES(sched_slice(&rq->cfs, se)); task_rq_unlock(rq, &flags); } read_unlock(&tasklist_lock);