lkml.org 
[lkml]   [2014]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/4] tracing/uprobes: Revert "Support mix of ftrace and perf"
(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




\
 
 \ /
  Last update: 2014-06-30 14:41    [W:0.255 / U:1.456 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site