Patch "perf probe: Use existing routine to look for a kernel module by dso->short_name" has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    perf probe: Use existing routine to look for a kernel module by dso->short_name

to the 4.2-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:
     perf-probe-use-existing-routine-to-look-for-a-kernel-module-by-dso-short_name.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 266fa2b22294909ddf6e7d2f8acfe07adf9fd978 Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Thu, 24 Sep 2015 11:24:18 -0300
Subject: perf probe: Use existing routine to look for a kernel module by dso->short_name

From: Arnaldo Carvalho de Melo <acme@redhat.com>

commit 266fa2b22294909ddf6e7d2f8acfe07adf9fd978 upstream.

We have map_groups__find_by_name() to look at the list of modules that
are in place for a given machine, so use it instead of traversing the
machine dso list, which also includes DSOs for userspace.

When merging the user and kernel DSO lists a bug was introduced where
'perf probe' stopped being able to add probes to modules using its short
name:

  # perf probe -m usbnet --add usbnet_start_xmit
  usbnet_start_xmit is out of .text, skip it.
    Error: Failed to add events.
  #

With this fix it works again:

  # perf probe -m usbnet --add usbnet_start_xmit
  Added new event:
    probe:usbnet_start_xmit (on usbnet_start_xmit in usbnet)

  You can now use it in all perf tools, such as:

  	perf record -e probe:usbnet_start_xmit -aR sleep 1
  #

Reported-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Fixes: 3d39ac538629 ("perf machine: No need to have two DSOs lists")
Link: http://lkml.kernel.org/r/20150924015008.GE1897@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 tools/perf/util/probe-event.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -274,12 +274,13 @@ static int kernel_get_module_dso(const c
 	int ret = 0;
 
 	if (module) {
-		list_for_each_entry(dso, &host_machine->dsos.head, node) {
-			if (!dso->kernel)
-				continue;
-			if (strncmp(dso->short_name + 1, module,
-				    dso->short_name_len - 2) == 0)
-				goto found;
+		char module_name[128];
+
+		snprintf(module_name, sizeof(module_name), "[%s]", module);
+		map = map_groups__find_by_name(&host_machine->kmaps, MAP__FUNCTION, module_name);
+		if (map) {
+			dso = map->dso;
+			goto found;
 		}
 		pr_debug("Failed to find module %s.\n", module);
 		return -ENOENT;


Patches currently in stable-queue which might be from acme@redhat.com are

queue-4.2/perf-tools-add-empty-build-files-for-architectures-lacking-them.patch
queue-4.2/perf-stat-get-correct-cpu-id-for-print_aggr.patch
queue-4.2/perf-probe-use-existing-routine-to-look-for-a-kernel-module-by-dso-short_name.patch
queue-4.2/perf-tools-add-missing-forward-declaration-of-struct-map-to-probe-event.h.patch
queue-4.2/perf-tools-fix-copying-of-proc-kcore.patch
queue-4.2/perf-hists-update-the-column-width-for-the-srcline-sort-key.patch
queue-4.2/perf-tools-fix-parse_events_add_pmu-caller.patch
queue-4.2/perf-header-fixup-reading-of-header_nrcpus-feature.patch