Re: [PATCH 1/2] ftrace: disable preemption on the testing of recursion
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2021-10-12 12:17:37
Also in:
linux-riscv, linuxppc-dev, lkml
On Tue, 12 Oct 2021 13:40:08 +0800 王贇 [off-list ref] wrote:
quoted hunk ↗ jump to hunk
@@ -52,11 +52,6 @@ static void notrace klp_ftrace_handler(unsigned long ip, bit = ftrace_test_recursion_trylock(ip, parent_ip); if (WARN_ON_ONCE(bit < 0)) return; - /* - * A variant of synchronize_rcu() is used to allow patching functions - * where RCU is not watching, see klp_synchronize_transition(). - */
I have to take a deeper look at this patch set, but do not remove this comment, as it explains the protection here, that is not obvious with the changes you made. -- Steve
- preempt_disable_notrace(); func = list_first_or_null_rcu(&ops->func_stack, struct klp_func, stack_node);