1 files changed, 52 insertions, 39 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index 7a4ae6d5ae..f8e543f1e3 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1785,74 +1785,87 @@ void getrusage(struct task_struct *p, int who, struct rusage *r)
 	struct task_struct *t;
 	unsigned long flags;
 	u64 tgutime, tgstime, utime, stime;
-	unsigned long maxrss = 0;
+	unsigned long maxrss;
+	struct mm_struct *mm;
+	struct signal_struct *sig = p->signal;
+	unsigned int seq = 0;
 
-	memset((char *)r, 0, sizeof (*r));
+retry:
+	memset(r, 0, sizeof(*r));
 	utime = stime = 0;
+	maxrss = 0;
 
 	if (who == RUSAGE_THREAD) {
 		task_cputime_adjusted(current, &utime, &stime);
 		accumulate_thread_rusage(p, r);
-		maxrss = p->signal->maxrss;
-		goto out;
+		maxrss = sig->maxrss;
+		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:
 	case RUSAGE_CHILDREN:
-		utime = p->signal->cutime;
-		stime = p->signal->cstime;
-		r->ru_nvcsw = p->signal->cnvcsw;
-		r->ru_nivcsw = p->signal->cnivcsw;
-		r->ru_minflt = p->signal->cmin_flt;
-		r->ru_majflt = p->signal->cmaj_flt;
-		r->ru_inblock = p->signal->cinblock;
-		r->ru_oublock = p->signal->coublock;
-		maxrss = p->signal->cmaxrss;
+		utime = sig->cutime;
+		stime = sig->cstime;
+		r->ru_nvcsw = sig->cnvcsw;
+		r->ru_nivcsw = sig->cnivcsw;
+		r->ru_minflt = sig->cmin_flt;
+		r->ru_majflt = sig->cmaj_flt;
+		r->ru_inblock = sig->cinblock;
+		r->ru_oublock = sig->coublock;
+		maxrss = sig->cmaxrss;
 
 		if (who == RUSAGE_CHILDREN)
 			break;
 		fallthrough;
 
 	case RUSAGE_SELF:
-		thread_group_cputime_adjusted(p, &tgutime, &tgstime);
-		utime += tgutime;
-		stime += tgstime;
-		r->ru_nvcsw += p->signal->nvcsw;
-		r->ru_nivcsw += p->signal->nivcsw;
-		r->ru_minflt += p->signal->min_flt;
-		r->ru_majflt += p->signal->maj_flt;
-		r->ru_inblock += p->signal->inblock;
-		r->ru_oublock += p->signal->oublock;
-		if (maxrss < p->signal->maxrss)
-			maxrss = p->signal->maxrss;
-		t = p;
-		do {
+		r->ru_nvcsw += sig->nvcsw;
+		r->ru_nivcsw += sig->nivcsw;
+		r->ru_minflt += sig->min_flt;
+		r->ru_majflt += sig->maj_flt;
+		r->ru_inblock += sig->inblock;
+		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);
-		} while_each_thread(p, t);
+		rcu_read_unlock();
+
 		break;
 
 	default:
 		BUG();
 	}
-	unlock_task_sighand(p, &flags);
 
-out:
-	r->ru_utime = ns_to_kernel_old_timeval(utime);
-	r->ru_stime = ns_to_kernel_old_timeval(stime);
+	if (need_seqretry(&sig->stats_lock, seq)) {
+		seq = 1;
+		goto retry;
+	}
+	done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
 
-	if (who != RUSAGE_CHILDREN) {
-		struct mm_struct *mm = get_task_mm(p);
+	if (who == RUSAGE_CHILDREN)
+		goto out_children;
 
-		if (mm) {
-			setmax_mm_hiwater_rss(&maxrss, mm);
-			mmput(mm);
-		}
+	thread_group_cputime_adjusted(p, &tgutime, &tgstime);
+	utime += tgutime;
+	stime += tgstime;
+
+out_thread:
+	mm = get_task_mm(p);
+	if (mm) {
+		setmax_mm_hiwater_rss(&maxrss, mm);
+		mmput(mm);
 	}
+
+out_children:
 	r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */
+	r->ru_utime = ns_to_kernel_old_timeval(utime);
+	r->ru_stime = ns_to_kernel_old_timeval(stime);
 }
 
 SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)