[PATCH] selftests: Fix Makefile to run targets even the ones in SKIP_TARGETS

[I Viswanath <viswanathiyyappan@gmail.com>]

With the current Makefile, if the user tries something like

make TARGETS="bpf mm"

only mm is run and bpf is skipped, which is not intentional.

`bpf` and `sched_ext` are always filtered out even when TARGETS is set
explicitly due to how SKIP_TARGETS is implemented.

This default skip exists because these tests require newer LLVM/Clang
versions that may not be available on all systems.

Fix the SKIP_TARGETS logic so that bpf and sched_ext remain
skipped when TARGETS is taken from the Makefile but are included when
the user specifies them explicitly.

Signed-off-by: I Viswanath <viswanathiyyappan@gmail.com>
---
make --silent summary=1 TARGETS="bpf size" kselftest

make[3]: Entering directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/bpf'

Auto-detecting system features:
...                                    llvm: [ OFF ]

Makefile:127: tools/build/Makefile.feature: No such file or directory
make[4]: *** No rule to make target 'tools/build/Makefile.feature'.  Stop.
make[3]: *** [Makefile:344: /home/user/kernel-dev/linux-next/tools/testing/selftests/bpf/tools/sbin/bpftool] Error 2
make[3]: Leaving directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/bpf'
make[3]: Nothing to be done for 'all'.
make[3]: Entering directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/bpf'

Auto-detecting system features:
...                                    llvm: [ OFF ]

Makefile:127: tools/build/Makefile.feature: No such file or directory
make[4]: *** No rule to make target 'tools/build/Makefile.feature'.  Stop.
make[3]: *** [Makefile:344: /home/user/kernel-dev/linux-next/tools/testing/selftests/bpf/tools/sbin/bpftool] Error 2
make[3]: Leaving directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/bpf'
TAP version 13
1..1
# selftests: size: get_size
ok 1 selftests: size: get_size

make --silent summary=1 kselftest (bpf is between arm64 and breakpoints in TARGETS)

make[3]: Nothing to be done for 'all'.
make[3]: Entering directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/alsa'
make[3]: Nothing to be done for 'all'.
make[3]: Leaving directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/alsa'
make[3]: Entering directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/amd-pstate'
make[3]: Nothing to be done for 'all'.
make[3]: Leaving directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/amd-pstate'
make[3]: Entering directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/arm64'
make[3]: Leaving directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/arm64'
make[3]: Entering directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/breakpoints'
make[3]: Nothing to be done for 'all'.
make[3]: Leaving directory '/home/user/kernel-dev/linux-next/tools/testing/selftests/breakpoints'
make[3]: Nothing to be done for 'all'.

 tools/testing/selftests/Makefile | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index babed7b1c2d1..c6cedb09c372 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -145,7 +145,10 @@ endif
 # User can optionally provide a TARGETS skiplist. By default we skip
 # targets using BPF since it has cutting edge build time dependencies
 # which require more effort to install.
-SKIP_TARGETS ?= bpf sched_ext
+ifeq ($(origin TARGETS), file)
+        SKIP_TARGETS ?= bpf sched_ext
+endif
+
 ifneq ($(SKIP_TARGETS),)
 	TMP := $(filter-out $(SKIP_TARGETS), $(TARGETS))
 	override TARGETS := $(TMP)
-- 
2.47.3