KVM selftests will soon need to use some of the cgroup creation and
deletion functionality from cgroup_util.

Suggested-by: David Matlack <dmatlack@google.com>
Signed-off-by: James Houghton <jthoughton@google.com>
---
 tools/testing/selftests/cgroup/Makefile       | 21 ++++++++++---------
 .../selftests/cgroup/{ => lib}/cgroup_util.c  |  3 +--
 .../cgroup/{ => lib/include}/cgroup_util.h    |  4 ++--
 .../testing/selftests/cgroup/lib/libcgroup.mk | 12 +++++++++++
 4 files changed, 26 insertions(+), 14 deletions(-)
 rename tools/testing/selftests/cgroup/{ => lib}/cgroup_util.c (99%)
 rename tools/testing/selftests/cgroup/{ => lib/include}/cgroup_util.h (99%)
 create mode 100644 tools/testing/selftests/cgroup/lib/libcgroup.mk

diff --git a/tools/testing/selftests/cgroup/Makefile b/tools/testing/selftests/cgroup/Makefile
index 1b897152bab6e..e01584c2189ac 100644
--- a/tools/testing/selftests/cgroup/Makefile
+++ b/tools/testing/selftests/cgroup/Makefile
@@ -21,14 +21,15 @@ TEST_GEN_PROGS += test_zswap
 LOCAL_HDRS += $(selfdir)/clone3/clone3_selftests.h $(selfdir)/pidfd/pidfd.h
 
 include ../lib.mk
+include lib/libcgroup.mk
 
-$(OUTPUT)/test_core: cgroup_util.c
-$(OUTPUT)/test_cpu: cgroup_util.c
-$(OUTPUT)/test_cpuset: cgroup_util.c
-$(OUTPUT)/test_freezer: cgroup_util.c
-$(OUTPUT)/test_hugetlb_memcg: cgroup_util.c
-$(OUTPUT)/test_kill: cgroup_util.c
-$(OUTPUT)/test_kmem: cgroup_util.c
-$(OUTPUT)/test_memcontrol: cgroup_util.c
-$(OUTPUT)/test_pids: cgroup_util.c
-$(OUTPUT)/test_zswap: cgroup_util.c
+$(OUTPUT)/test_core: $(LIBCGROUP_O)
+$(OUTPUT)/test_cpu: $(LIBCGROUP_O)
+$(OUTPUT)/test_cpuset: $(LIBCGROUP_O)
+$(OUTPUT)/test_freezer: $(LIBCGROUP_O)
+$(OUTPUT)/test_hugetlb_memcg: $(LIBCGROUP_O)
+$(OUTPUT)/test_kill: $(LIBCGROUP_O)
+$(OUTPUT)/test_kmem: $(LIBCGROUP_O)
+$(OUTPUT)/test_memcontrol: $(LIBCGROUP_O)
+$(OUTPUT)/test_pids: $(LIBCGROUP_O)
+$(OUTPUT)/test_zswap: $(LIBCGROUP_O)
diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/lib/cgroup_util.c
similarity index 99%
rename from tools/testing/selftests/cgroup/cgroup_util.c
rename to tools/testing/selftests/cgroup/lib/cgroup_util.c
index 1e2d46636a0ca..d5649486a11df 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/lib/cgroup_util.c
@@ -16,8 +16,7 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
-#include "cgroup_util.h"
-#include "../clone3/clone3_selftests.h"
+#include <cgroup_util.h>
 
 /* Returns read len on success, or -errno on failure. */
 static ssize_t read_text(const char *path, char *buf, size_t max_len)
diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/lib/include/cgroup_util.h
similarity index 99%
rename from tools/testing/selftests/cgroup/cgroup_util.h
rename to tools/testing/selftests/cgroup/lib/include/cgroup_util.h
index 19b131ee77072..7a0441e5eb296 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.h
+++ b/tools/testing/selftests/cgroup/lib/include/cgroup_util.h
@@ -2,9 +2,9 @@
 #include <stdbool.h>
 #include <stdlib.h>
 
-#include "../kselftest.h"
-
+#ifndef PAGE_SIZE
 #define PAGE_SIZE 4096
+#endif
 
 #define MB(x) (x << 20)
 
diff --git a/tools/testing/selftests/cgroup/lib/libcgroup.mk b/tools/testing/selftests/cgroup/lib/libcgroup.mk
new file mode 100644
index 0000000000000..2cbf07337c23f
--- /dev/null
+++ b/tools/testing/selftests/cgroup/lib/libcgroup.mk
@@ -0,0 +1,12 @@
+CGROUP_DIR := $(selfdir)/cgroup
+
+LIBCGROUP_C := lib/cgroup_util.c
+
+LIBCGROUP_O := $(patsubst %.c, $(OUTPUT)/%.o, $(LIBCGROUP_C))
+
+CFLAGS += -I$(CGROUP_DIR)/lib/include
+
+$(LIBCGROUP_O): $(OUTPUT)/%.o : $(CGROUP_DIR)/%.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o $@
+
+EXTRA_CLEAN += $(LIBCGROUP_O)
-- 
2.49.0.395.g12beb8f557-goog

Hello James.

On Thu, Mar 27, 2025 at 01:23:48AM +0000, James Houghton <jthoughton@google.com> wrote:
> KVM selftests will soon need to use some of the cgroup creation and
> deletion functionality from cgroup_util.

Thanks, I think cross-selftest sharing is better than duplicating
similar code. 

+Cc: Yafang as it may worth porting/unifying with
tools/testing/selftests/bpf/cgroup_helpers.h too

> --- a/tools/testing/selftests/cgroup/cgroup_util.c
> +++ b/tools/testing/selftests/cgroup/lib/cgroup_util.c
> @@ -16,8 +16,7 @@
>  #include <sys/wait.h>
>  #include <unistd.h>
>  
> -#include "cgroup_util.h"
> -#include "../clone3/clone3_selftests.h"
> +#include <cgroup_util.h>

The clone3_selftests.h header is not needed anymore?


Michal

On Thu, Mar 27, 2025 at 5:43 PM Michal Koutný <mkoutny@suse.com> wrote:
>
> Hello James.
>
> On Thu, Mar 27, 2025 at 01:23:48AM +0000, James Houghton <jthoughton@google.com> wrote:
> > KVM selftests will soon need to use some of the cgroup creation and
> > deletion functionality from cgroup_util.
>
> Thanks, I think cross-selftest sharing is better than duplicating
> similar code.
>
> +Cc: Yafang as it may worth porting/unifying with
> tools/testing/selftests/bpf/cgroup_helpers.h too

Thanks for pointing that out—that’s a good suggestion. We should also
consider migrating the bpf cgroup helpers into the new libcgroup.


--
Regards
Yafang

On Thu, Mar 27, 2025 at 2:43 AM Michal Koutný <mkoutny@suse.com> wrote:
>
> Hello James.
>
> On Thu, Mar 27, 2025 at 01:23:48AM +0000, James Houghton <jthoughton@google.com> wrote:
> > KVM selftests will soon need to use some of the cgroup creation and
> > deletion functionality from cgroup_util.
>
> Thanks, I think cross-selftest sharing is better than duplicating
> similar code.
>
> +Cc: Yafang as it may worth porting/unifying with
> tools/testing/selftests/bpf/cgroup_helpers.h too
>
> > --- a/tools/testing/selftests/cgroup/cgroup_util.c
> > +++ b/tools/testing/selftests/cgroup/lib/cgroup_util.c
> > @@ -16,8 +16,7 @@
> >  #include <sys/wait.h>
> >  #include <unistd.h>
> > 
> > -#include "cgroup_util.h"
> > -#include "../clone3/clone3_selftests.h"
> > +#include <cgroup_util.h>
>
> The clone3_selftests.h header is not needed anymore?

Ah, sorry.

We do indeed still reference `sys_clone3()` from cgroup_util.c, so it should
stay in (as "../../clone3/clone3_selftests.h"). I realize now that it compiled
just fine because the call to `sys_clone3()` is dropped entirely when
clone3_selftests.h is not included.

So I'll apply the following diff:

diff --git a/tools/testing/selftests/cgroup/lib/cgroup_util.c b/tools/testing/selftests/cgroup/lib/cgroup_util.c
index d5649486a11df..fe15541f3a07d 100644
--- a/tools/testing/selftests/cgroup/lib/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/lib/cgroup_util.c
@@ -18,6 +18,8 @@
 
 #include <cgroup_util.h>
 
+#include "../../clone3/clone3_selftests.h"
+
 /* Returns read len on success, or -errno on failure. */
 static ssize_t read_text(const char *path, char *buf, size_t max_len)
 {
diff --git a/tools/testing/selftests/cgroup/lib/libcgroup.mk b/tools/testing/selftests/cgroup/lib/libcgroup.mk
index 2cbf07337c23f..12323041a5ce6 100644
--- a/tools/testing/selftests/cgroup/lib/libcgroup.mk
+++ b/tools/testing/selftests/cgroup/lib/libcgroup.mk
@@ -6,7 +6,9 @@ LIBCGROUP_O := $(patsubst %.c, $(OUTPUT)/%.o, $(LIBCGROUP_C))
 
 CFLAGS += -I$(CGROUP_DIR)/lib/include
 
-$(LIBCGROUP_O): $(OUTPUT)/%.o : $(CGROUP_DIR)/%.c
+EXTRA_HDRS := $(selfdir)/clone3/clone3_selftests.h
+
+$(LIBCGROUP_O): $(OUTPUT)/%.o : $(CGROUP_DIR)/%.c $(EXTRA_HDRS)
 	$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o $@
 
 EXTRA_CLEAN += $(LIBCGROUP_O)