[PATCH 1/4] perf: Enable libtracefs dynamic linking

[Ian Rogers]

Currently libtracefs isn't used by perf, but there are potential
improvements by using it as identified Steven Rostedt's e-mail:
https://lore.kernel.org/lkml/20210610154759.1ef958f0@xxxxxxxxxxxxxxxx/

This change is modelled on the dynamic libtraceevent patch by Michael
Petlan:
https://lore.kernel.org/linux-perf-users/20210428092023.4009-1-mpetlan@xxxxxxxxxx/

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/build/Makefile.feature | 1 +
 tools/build/feature/Makefile | 4 ++++
 tools/perf/Makefile.config   | 9 +++++++++
 tools/perf/Makefile.perf     | 2 ++
 4 files changed, 16 insertions(+)

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 04a8e3db8a54..c87e876b6dd7 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -53,6 +53,7 @@ FEATURE_TESTS_BASIC :=                  \
         libslang                        \
         libslang-include-subdir         \
         libtraceevent                   \
+        libtracefs                      \
         libcrypto                       \
         libunwind                       \
         pthread-attr-setaffinity-np     \
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index ec203e28407f..9488c4b4026e 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -37,6 +37,7 @@ FILES=                                          \
          test-libslang.bin                      \
          test-libslang-include-subdir.bin       \
          test-libtraceevent.bin                 \
+         test-libtracefs.bin                    \
          test-libcrypto.bin                     \
          test-libunwind.bin                     \
          test-libunwind-debug-frame.bin         \
@@ -200,6 +201,9 @@ $(OUTPUT)test-libslang-include-subdir.bin:
 $(OUTPUT)test-libtraceevent.bin:
 	$(BUILD) -ltraceevent
 
+$(OUTPUT)test-libtracefs.bin:
+	$(BUILD) -ltracefs
+
 $(OUTPUT)test-libcrypto.bin:
 	$(BUILD) -lcrypto
 
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index a62d09808fef..3a8a54b71654 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -1098,6 +1098,15 @@ ifdef LIBTRACEEVENT_DYNAMIC
   endif
 endif
 
+ifdef LIBTRACEFS_DYNAMIC
+  $(call feature_check,libtracefs)
+  ifeq ($(feature-libtracefs), 1)
+    EXTLIBS += -ltracefs
+  else
+    dummy := $(error Error: No libtracefs devel library found, please install libtracefs-dev);
+  endif
+endif
+
 # Among the variables below, these:
 #   perfexecdir
 #   perf_include_dir
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index e47f04e5b51e..b56e26b703ff 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -130,6 +130,8 @@ include ../scripts/utilities.mak
 #
 # Define LIBTRACEEVENT_DYNAMIC to enable libtraceevent dynamic linking
 #
+# Define LIBTRACEFS_DYNAMIC to enable libtracefs dynamic linking
+#
 
 # As per kernel Makefile, avoid funny character set dependencies
 unexport LC_ALL
-- 
2.32.0.288.g62a8d224e6-goog