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@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Link: https://lore.kernel.org/r/20230821134428.2504912-1-willy@infradead.org

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 0014d3adaf8460b03b4ad2e4ccaf97b17b7a8884..9610bad018a39fb388ca9e27b226d11e9cf20510 100644 (file)
--- 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)