[PATCH V2] rtla: Fix Makefile when called from -C tools/

[Daniel Bristot de Oliveira]

Sedat Dilek reported an error on rtla Makefile when running:

    $ make -C tools/ clean
    [...]
    make[2]: Entering directory
    '/home/dileks/src/linux-kernel/git/tools/tracing/rtla'
    [...]
    '/home/dileks/src/linux-kernel/git/Documentation/tools/rtla'
    /bin/sh: 1: test: rtla-make[2]:: unexpected operator    <------ The problem
    rm: cannot remove '/home/dileks/src/linux-kernel/git': Is a directory
    make[2]: *** [Makefile:120: clean] Error 1
    make[2]: Leaving directory

This occurred because the rtla calls kernel's Makefile to get the
version in silence mode, e.g.,

    $ make -sC ../../.. kernelversion
    5.19.0-rc4

But the -s is being ignored when rtla's makefile is called indirectly,
so the output looks like this:

    $ make -C ../../.. kernelversion
    make: Entering directory '/root/linux'
    5.19.0-rc4
    make: Leaving directory '/root/linux'

Using 'grep -v make' avoids this problem, e.g.,

    $ make -C ../../.. kernelversion | grep -v make
    5.19.0-rc4

Thus, add | grep -v make.

Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Fixes: 8619e32825fd ("rtla: Follow kernel version")
Reported-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
---
 tools/tracing/rtla/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile
index 3822f4ea5f49..1bea2d16d4c1 100644
--- a/tools/tracing/rtla/Makefile
+++ b/tools/tracing/rtla/Makefile
@@ -1,6 +1,6 @@
 NAME	:=	rtla
 # Follow the kernel version
-VERSION :=	$(shell cat VERSION 2> /dev/null || make -sC ../../.. kernelversion)
+VERSION :=	$(shell cat VERSION 2> /dev/null || make -sC ../../.. kernelversion | grep -v make)
 
 # From libtracefs:
 # Makefiles suck: This macro sets a default value of $(2) for the
-- 
2.32.0