Messages in this thread | | | Date | Mon, 30 Jun 2014 20:52:21 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH 1/4] tracing/uprobes: Revert "Support mix of ftrace and perf" |
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(2014/06/28 2:01), Oleg Nesterov wrote: > This reverts commit 43fe98913c9f67e3b523615ee3316f9520a623e0. > > This patch is very wrong. Firstly, this change leads to unbalanced > uprobe_unregister(). Just for example, > > # perf probe -x /lib/libc.so.6 syscall > # echo 1 >> /sys/kernel/debug/tracing/events/probe_libc/enable > # perf record -e probe_libc:syscall whatever > > after that uprobe is dead (unregistered) but the user of ftrace/perf > can't know this, and it looks as if nobody hits this probe. > > This would be easy to fix, but there are other reasons why it is not > simple to mix ftrace and perf. If nothing else, they can't share the > same ->consumer.filter. This is fixable too, but probably we need to > fix the poorly designed uprobe_register() interface first. At least > "register" and "apply" should be clearly separated.
Hm, it should be a uprobes original issue. it's different from kprobes.
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Thank you,
> > Cc: stable@vger.kernel.org # v3.14 > Signed-off-by: Oleg Nesterov <oleg@redhat.com> > --- > kernel/trace/trace_uprobe.c | 9 ++++++++- > 1 files changed, 8 insertions(+), 1 deletions(-) > > diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c > index 04fdb5d..08e7970 100644 > --- a/kernel/trace/trace_uprobe.c > +++ b/kernel/trace/trace_uprobe.c > @@ -893,6 +893,9 @@ probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file, > int ret; > > if (file) { > + if (tu->tp.flags & TP_FLAG_PROFILE) > + return -EINTR; > + > link = kmalloc(sizeof(*link), GFP_KERNEL); > if (!link) > return -ENOMEM; > @@ -901,8 +904,12 @@ probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file, > list_add_tail_rcu(&link->list, &tu->tp.files); > > tu->tp.flags |= TP_FLAG_TRACE; > - } else > + } else { > + if (tu->tp.flags & TP_FLAG_TRACE) > + return -EINTR; > + > tu->tp.flags |= TP_FLAG_PROFILE; > + } > > ret = uprobe_buffer_enable(); > if (ret < 0) >
-- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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