Commit d4c157c7 authored by Boqun Feng's avatar Boqun Feng Committed by Peter Zijlstra
Browse files

locking/lockdep: Remove the unnecessary trace saving 



In print_bad_irq_dependency(), save_trace() is called to set the ->trace
for @prev_root as the current call trace, however @prev_root corresponds
to the the held lock, which may not be acquired in current call trace,
therefore it's wrong to use save_trace() to set ->trace of @prev_root.
Moreover, with our adjustment of printing backwards dependency path, the
->trace of @prev_root is unncessary, so remove it.

Reported-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210618170110.3699115-3-boqun.feng@gmail.com
parent 69c7a5fb

kernel/locking/lockdep.c

+0 −3
Original line number Diff line number Diff line
@@ -2550,9 +2550,6 @@ print_bad_irq_dependency(struct task_struct *curr, 
	lockdep_print_held_locks(curr);



	pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);

	prev_root->trace = save_trace();

	if (!prev_root->trace)

		return;

	print_shortest_lock_dependencies_backwards(backwards_entry, prev_root);



	pr_warn("\nthe dependencies between the lock to be acquired");