Commit 1feb2cc8 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

lockdep: Explicitly flag likely false-positive report 



The reason that lockdep_rcu_suspicious() prints the value of debug_locks
is because a value of zero indicates a likely false positive.  This can
work, but is a bit obtuse.  This commit therefore explicitly calls out
the possibility of a false positive.

Reviewed-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 27ba76e1

kernel/locking/lockdep.c

+4 −2
Original line number Diff line number Diff line
@@ -6393,6 +6393,7 @@ asmlinkage __visible void lockdep_sys_exit(void) 
void lockdep_rcu_suspicious(const char *file, const int line, const char *s)

{

	struct task_struct *curr = current;

	int dl = READ_ONCE(debug_locks);



	/* Note: the following can be executed concurrently, so be careful. */

	pr_warn("\n");
@@ -6402,11 +6403,12 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s) 
	pr_warn("-----------------------------\n");

	pr_warn("%s:%d %s!\n", file, line, s);

	pr_warn("\nother info that might help us debug this:\n\n");

	pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",

	pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n%s",

	       !rcu_lockdep_current_cpu_online()

			? "RCU used illegally from offline CPU!\n"

			: "",

	       rcu_scheduler_active, debug_locks);

	       rcu_scheduler_active, dl,

	       dl ? "" : "Possible false positive due to lockdep disabling via debug_locks = 0\n");



	/*

	 * If a CPU is in the RCU-free window in idle (ie: in the section