FAILED: patch "[PATCH] tracing/uprobes: Revert "Support mix of ftrace and perf"" failed to apply to 3.14-stable tree

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The patch below does not apply to the 3.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 48212542067a7ff6cbe829dbae279c2ff7557b44 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Date: Fri, 27 Jun 2014 19:01:36 +0200
Subject: [PATCH] tracing/uprobes: Revert "Support mix of ftrace and perf"

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>
Cc: stable@xxxxxxxxxxxxxxx # v3.14
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>

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 04fdb5de823c..08e7970bf3f9 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)

--
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