perf tools: Handle --version string generation on machines without git

If git is installed we'll have a 'perf --version' output of this form:

$ make -j8 -C tools/perf/ O=/home/acme/git/build/perf install
$ perf --version
perf version 3.7.rc3.g3afad6

Now on a machine without git installed:

$ mv  /home/acme/bin/git /home/acme/bin/git.OFF
$ make -j8 -C tools/perf/ O=/home/acme/git/build/perf install
$ perf --version
perf version 3.7.0-rc2

That is, no error message due to git not being installed will appear on the
screen and instead the version string in the top level Makefile will be
used.

Requested-by: Ingo Molnar <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/tools/perf/util/PERF-VERSION-GEN b/tools/perf/util/PERF-VERSION-GEN
index ac418a1255e6..6aa34e5afdcf 100755
--- a/tools/perf/util/PERF-VERSION-GEN
+++ b/tools/perf/util/PERF-VERSION-GEN
@@ -14,8 +14,9 @@ LF='
 # otherwise try to get the version from the kernel Makefile
 #
 if test -d ../../.git -o -f ../../.git &&
-	VN=$(echo $(git tag -l "v[0-9].[0-9]*" | tail -1)"-g"$(git log -1 --abbrev=4 --pretty=format:"%h" HEAD) 2>/dev/null)
+	VN=$(git tag 2>/dev/null | tail -1 | grep -E "v[0-9].[0-9]*")
 then
+	VN=$(echo $VN"-g"$(git log -1 --abbrev=4 --pretty=format:"%h" HEAD))
 	VN=$(echo "$VN" | sed -e 's/-/./g');
 else
 	VN=$(MAKEFLAGS= make -sC ../.. kernelversion)