Re: [PATCH v2 1/5] perf probe: Split add_perf_probe_events()

From: Wangnan (F)
Date: Sun Sep 06 2015 - 03:48:38 EST


Hi Namhyung,

Thanks for this patchset.

Could you plase have a look at patch 5/27 and 6/27 in my newest pull request?
These 2 patches utilize new probing API to create probe point and collect
probe_trace_events. I'm not very sure I fully understand your design principle,
especially the cleanup part, because I can see different functions dealing with
cleanup:

cleanup_perf_probe_events
del_perf_probe_events
clear_perf_probe_event
clear_probe_trace_event

But non of them works perfectly for me.

In bpf_prog_priv__clear() function of 6/27, I copied some code from
cleanup_perf_probe_events(), because I think when destroying bpf programs,
the probe_trace_events should also be cleanuped, but we don't need call
exit_symbol_maps() many times, because we are in 'perf record', and not
sure whether other parts of perf need symbol maps. Otherwise I think directly
calling cleanup_perf_probe_events() sould be better.

You can find patch from:

http://lkml.kernel.org/n/1441523623-152703-6-git-send-email-wangnan0@xxxxxxxxxx

http://lkml.kernel.org/n/1441523623-152703-7-git-send-email-wangnan0@xxxxxxxxxx

Thank you.

On 2015/9/4 20:15, Namhyung Kim wrote:
The add_perf_probe_events() does 3 things:

1. convert all perf events to trace events
2. add all trace events to kernel
3. cleanup all trace events

But sometimes we need to do something with the trace events. So split
the funtion into three, so that it can access intermediate trace events
via struct __event_package if needed.

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
tools/perf/util/probe-event.c | 39 +++++++++++++++++++++++++++++++++++----
1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index eb5f18b75402..2c762f41e7a5 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -2765,9 +2765,10 @@ struct __event_package {
int ntevs;
};
-int add_perf_probe_events(struct perf_probe_event *pevs, int npevs)
+static int convert_perf_probe_events(struct perf_probe_event *pevs, int npevs,
+ struct __event_package **ppkgs)
{
- int i, j, ret;
+ int i, ret;
struct __event_package *pkgs;
ret = 0;
@@ -2792,12 +2793,21 @@ int add_perf_probe_events(struct perf_probe_event *pevs, int npevs)
ret = convert_to_probe_trace_events(pkgs[i].pev,
&pkgs[i].tevs);
if (ret < 0)
- goto end;
+ return ret;
pkgs[i].ntevs = ret;
}
/* This just release blacklist only if allocated */
kprobe_blacklist__release();
+ *ppkgs = pkgs;
+
+ return 0;
+}
+
+static int apply_perf_probe_events(struct __event_package *pkgs, int npevs)
+{
+ int i, ret = 0;
+
/* Loop 2: add all events */
for (i = 0; i < npevs; i++) {
ret = __add_probe_trace_events(pkgs[i].pev, pkgs[i].tevs,
@@ -2806,7 +2816,16 @@ int add_perf_probe_events(struct perf_probe_event *pevs, int npevs)
if (ret < 0)
break;
}
-end:
+ return ret;
+}
+
+static void cleanup_perf_probe_events(struct __event_package *pkgs, int npevs)
+{
+ int i, j;
+
+ if (pkgs == NULL)
+ return;
+
/* Loop 3: cleanup and free trace events */
for (i = 0; i < npevs; i++) {
for (j = 0; j < pkgs[i].ntevs; j++)
@@ -2815,6 +2834,18 @@ end:
}
free(pkgs);
exit_symbol_maps();
+}
+
+int add_perf_probe_events(struct perf_probe_event *pevs, int npevs)
+{
+ int ret;
+ struct __event_package *pkgs = NULL;
+
+ ret = convert_perf_probe_events(pevs, npevs, &pkgs);
+ if (ret == 0)
+ ret = apply_perf_probe_events(pkgs, npevs);
+
+ cleanup_perf_probe_events(pkgs, npevs);
return ret;
}


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