Hi Taeung, On Sun, 22 Mar 2020 23:06:20 +0900 Taeung Song <treeze.taeung@xxxxxxxxx> wrote: > Hi, > > After setting 'maxactive' for kretprobe, > how can I recheck the value of 'maxactive' ? > For example, in order to distinguish the difference > between two kretprobe events > (kmem_cache_alloc_node and kmem_cache_alloc_node10) > > $ cd /sys/kernel/debug/tracing > $ echo 'r:kmem_cache_alloc_node kmem_cache_alloc_node' >> kprobe_events > $ echo 'r10:kmem_cache_alloc_node10 kmem_cache_alloc_node' >> > kprobe_events > > $ cat kprobe_events > r:kprobes/kmem_cache_alloc_node kmem_cache_alloc_node > r:kprobes/kmem_cache_alloc_node10 kmem_cache_alloc_node Oops! good catch. That must be a bug, since the kprobe_events design policy is to support following operation. $ cat kprobe_events > /etc/event_setting (reboot) $ cat /etc/event_setting > kprobe_events What about below patch? >From 935ed56819f2bfb7ac977f5c63273c9a6e3dfb42 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Date: Mon, 23 Mar 2020 10:57:48 +0900 Subject: [PATCH] ftrace/kprobe: Show the maxactive number on kprobe_events Show maxactive parameter on kprobe_events. This allows user to save the current configuration and restore it without losing maxactive parameter. Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> --- kernel/trace/trace_kprobe.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 362cca52f5de..d0568af4a0ef 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1078,6 +1078,8 @@ static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev) int i; seq_putc(m, trace_kprobe_is_return(tk) ? 'r' : 'p'); + if (trace_kprobe_is_return(tk) && tk->rp.maxactive) + seq_printf(m, "%d", tk->rp.maxactive); seq_printf(m, ":%s/%s", trace_probe_group_name(&tk->tp), trace_probe_name(&tk->tp)); -- 2.20.1 Thank you, -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
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