From e1bf58e6469ec6eda6720bfeb4bbd09a0b8e6226 Mon Sep 17 00:00:00 2001 From: Kui-Feng Lee Date: Mon, 1 Apr 2024 12:16:21 -0700 Subject: [PATCH] rethook: Remove warning messages printed for finding return address of a frame. rethook_find_ret_addr() prints a warning message and returns 0 when the target task is running and not the "current" task to prevent returning an incorrect return address. However, this check is incomplete as the target task can still transition to the running state when finding the return address, although it is safe with RCU. The issue we encounter is that the kernel frequently prints warning messages when BPF profiling programs call to bpf_get_task_stack() on running tasks. The callers should be aware and willing to take the risk of receiving an incorrect return address from a task that is currently running other than the "current" one. A warning is not needed here as the callers are intent on it. Signed-off-by: Kui-Feng Lee Acked-by: Andrii Nakryiko --- kernel/trace/rethook.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c index fa03094e9e698..4297a132a7ae2 100644 --- a/kernel/trace/rethook.c +++ b/kernel/trace/rethook.c @@ -248,7 +248,7 @@ unsigned long rethook_find_ret_addr(struct task_struct *tsk, unsigned long frame if (WARN_ON_ONCE(!cur)) return 0; - if (WARN_ON_ONCE(tsk != current && task_is_running(tsk))) + if (tsk != current && task_is_running(tsk)) return 0; do {