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

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 <[email protected]> know about it.

From: Arnaldo Carvalho de Melo <[email protected]>
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 <[email protected]>

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
#

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

@@ -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 [email protected] 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