[tip: sched/core] sched: Assert for_each_thread() is properly locked

[tip-bot2 for Matthew Wilcox (Oracle)]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     4de7b17fd05d03fa919e8c47fc66122bd24d7b6c
Gitweb:        https://git.kernel.org/tip/4de7b17fd05d03fa919e8c47fc66122bd24d7b6c
Author:        Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
AuthorDate:    Mon, 21 Aug 2023 14:44:28 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 15 Sep 2023 10:33:29 +02:00

sched: Assert for_each_thread() is properly locked

list_for_each_entry_rcu() takes an optional fourth argument which
allows RCU to assert that the correct lock is held.  Several callers
of for_each_thread() rely on their caller to be holding the appropriate
lock, so this is a useful assertion to include.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230821134428.2504912-1-willy@xxxxxxxxxxxxx
---
 include/linux/sched/signal.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 0014d3a..9610bad 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -656,7 +656,8 @@ extern bool current_is_single_threaded(void);
 	while ((t = next_thread(t)) != g)
 
 #define __for_each_thread(signal, t)	\
-	list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
+	list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node, \
+		lockdep_is_held(&tasklist_lock))
 
 #define for_each_thread(p, t)		\
 	__for_each_thread((p)->signal, t)