This is a note to let you know that I've just added the patch titled
tracing/uprobes: Revert "Support mix of ftrace and perf"
to the 3.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-uprobes-revert-support-mix-of-ftrace-and-perf.patch
and it can be found in the queue-3.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 48212542067a7ff6cbe829dbae279c2ff7557b44 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Date: Fri, 27 Jun 2014 19:01:36 +0200
Subject: tracing/uprobes: Revert "Support mix of ftrace and perf"
From: Oleg Nesterov <oleg@xxxxxxxxxx>
commit 48212542067a7ff6cbe829dbae279c2ff7557b44 upstream.
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.
Link: http://lkml.kernel.org/p/20140627170136.GA18319@xxxxxxxxxx
Cc: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
Cc: "zhangwei(Jovi)" <jovi.zhangwei@xxxxxxxxxx>
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Acked-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace_uprobe.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -893,6 +893,9 @@ probe_event_enable(struct trace_uprobe *
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 *
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)
Patches currently in stable-queue which might be from oleg@xxxxxxxxxx are
queue-3.15/tracing-uprobes-fix-the-usage-of-uprobe_buffer_enable-in-probe_event_enable.patch
queue-3.15/tracing-uprobes-revert-support-mix-of-ftrace-and-perf.patch
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