From 984035ad7b247ccc62b06e113eea3fc673f114cc Mon Sep 17 00:00:00 2001
From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Date: Wed, 25 Sep 2019 16:48:20 -0700
Subject: [PATCH] ipc/sem.c: convert to use built-in RCU list checking

CONFIG_PROVE_RCU_LIST requires list_for_each_entry_rcu() to pass a lockdep
expression if using srcu or locking for protection.  It can only check
regular RCU protection, all other protection needs to be passed as lockdep
expression.

Link: http://lkml.kernel.org/r/20190830231817.76862-2-joel@joelfernandes.org
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Jonathan Derrick <jonathan.derrick@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 ipc/sem.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ipc/sem.c b/ipc/sem.c
index 7da4504bcc7c..ec97a7072413 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1852,7 +1852,8 @@ static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid)
 {
 	struct sem_undo *un;
 
-	list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) {
+	list_for_each_entry_rcu(un, &ulp->list_proc, list_proc,
+				spin_is_locked(&ulp->lock)) {
 		if (un->semid == semid)
 			return un;
 	}