kasan: Record work creation stack trace with interrupts enabled

Recording the work creation stack trace for KASAN reports in
call_rcu() is expensive, due to unwinding the stack, but also
due to acquiring depot_lock inside stackdepot (which may be contended).
Because calling kasan_record_aux_stack_noalloc() does not require
interrupts to already be disabled, this may unnecessarily extend
the time with interrupts disabled.

Therefore, move calling kasan_record_aux_stack() before the section
with interrupts disabled.

Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index f1bb7cc..ca8d7dd 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3060,8 +3060,8 @@ void call_rcu(struct rcu_head *head, rcu_callback_t func)
        }
        head->func = func;
        head->next = NULL;
-       local_irq_save(flags);
        kasan_record_aux_stack_noalloc(head);
+       local_irq_save(flags);
        rdp = this_cpu_ptr(&rcu_data);
 
        /* Add the callback to our list. */