diff --git a/kernel/sys.c b/kernel/sys.c index 85f358a5d5eb..2cfb829864c6 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1766,7 +1766,9 @@ void getrusage(struct task_struct *p, int who, struct rusage *r) unsigned long maxrss; struct mm_struct *mm; struct signal_struct *sig = p->signal; + unsigned int seq = 0; +retry: memset(r, 0, sizeof(*r)); utime = stime = 0; maxrss = 0; @@ -1778,8 +1780,7 @@ void getrusage(struct task_struct *p, int who, struct rusage *r) goto out_thread; } - if (!lock_task_sighand(p, &flags)) - return; + flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq); switch (who) { case RUSAGE_BOTH: @@ -1807,14 +1808,23 @@ void getrusage(struct task_struct *p, int who, struct rusage *r) r->ru_oublock += sig->oublock; if (maxrss < sig->maxrss) maxrss = sig->maxrss; + + rcu_read_lock(); __for_each_thread(sig, t) accumulate_thread_rusage(t, r); + rcu_read_unlock(); + break; default: BUG(); } - unlock_task_sighand(p, &flags); + + if (need_seqretry(&sig->stats_lock, seq)) { + seq = 1; + goto retry; + } + done_seqretry_irqrestore(&sig->stats_lock, seq, flags); if (who == RUSAGE_CHILDREN) goto out_children;