linux-kernel - [PATCH][GIT PULL][v2.6.35] perf/tracing: Fix regression of perf losing kprobe events

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Date:	Thu, 10 Jun 2010 20:58:39 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Subject: [PATCH][GIT PULL][v2.6.35] perf/tracing: Fix regression of perf
 losing kprobe events


Ingo,

Please pull the latest tip/perf/urgent tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/perf/urgent


Steven Rostedt (1):
      perf/tracing: Fix regression of perf losing kprobe events

----
 kernel/trace/trace_event_perf.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---------------------------
commit a8fb2608053547bc3152ea61a5ec7cdfce5d942c
Author: Steven Rostedt <srostedt@...hat.com>
Date:   Thu Jun 10 14:53:16 2010 -0400

    perf/tracing: Fix regression of perf losing kprobe events
    
    With the addition of the code to shrink the kernel tracepoint
    infrastructure, we lost kprobes being traced by perf. The reason
    is that I tested if the "tp_event->class->perf_probe" existed before
    enabling it. This prevents "ftrace only" events (like the function
    trace events) from being enabled by perf.
    
    Unfortunately, kprobe events do not use perf_probe. This causes
    kprobes to be missed by perf. To fix this, we add the test to
    see if "tp_event->class->reg" exists as well as perf_probe.
    
    Normal trace events have only "perf_probe" but no "reg" function,
    and kprobes and syscalls have the "reg" but no "perf_probe".
    The ftrace unique events do not have either, so this is a valid
    test. If a kprobe or syscall is not to be probed by perf, the
    "reg" function is called anyway, and will return a failure and
    prevent perf from probing it.
    
    Reported-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
    Tested-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
    Acked-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
    Signed-off-by: Steven Rostedt <rostedt@...dmis.org>

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index e6f6588..8a2b73f 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -96,7 +96,9 @@ int perf_trace_init(struct perf_event *p_event)
 	mutex_lock(&event_mutex);
 	list_for_each_entry(tp_event, &ftrace_events, list) {
 		if (tp_event->event.type == event_id &&
-		    tp_event->class && tp_event->class->perf_probe &&
+		    tp_event->class &&
+		    (tp_event->class->perf_probe ||
+		     tp_event->class->reg) &&
 		    try_module_get(tp_event->mod)) {
 			ret = perf_trace_event_init(tp_event, p_event);
 			break;


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