[PATCH bpf-next v2 3/4] selftests/bpf: libarena: add explicit buddy_grow() call

[Emil Tsalapatis <emil@etsalapatis.com>]

Add an API call for explicitly growing the arena through
page allocation. Useful for programs that do not do so
implicitly through buddy_alloc().

Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
---
 .../bpf/libarena/include/libarena/buddy.h     |  1 +
 .../selftests/bpf/libarena/src/buddy.bpf.c    | 26 +++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/tools/testing/selftests/bpf/libarena/include/libarena/buddy.h b/tools/testing/selftests/bpf/libarena/include/libarena/buddy.h
index 958450fc5f9d..90674ac077df 100644
--- a/tools/testing/selftests/bpf/libarena/include/libarena/buddy.h
+++ b/tools/testing/selftests/bpf/libarena/include/libarena/buddy.h
@@ -78,5 +78,6 @@ int buddy_destroy(struct buddy __arena *buddy);
 int buddy_free(struct buddy __arena *buddy, void __arena *free);
 void __arena *buddy_alloc(struct buddy __arena *buddy, size_t size);
 void __arena *buddy_alloc_nogrow(struct buddy __arena *buddy, size_t size);
+int buddy_grow(struct buddy __arena *buddy, size_t nr_chunks);
 
 #endif /* __BPF__  */
diff --git a/tools/testing/selftests/bpf/libarena/src/buddy.bpf.c b/tools/testing/selftests/bpf/libarena/src/buddy.bpf.c
index ed359d4af1f4..d12c8924a0ad 100644
--- a/tools/testing/selftests/bpf/libarena/src/buddy.bpf.c
+++ b/tools/testing/selftests/bpf/libarena/src/buddy.bpf.c
@@ -812,6 +812,32 @@ void __arena *buddy_alloc_nogrow(struct buddy __arena *buddy, size_t size)
 	return buddy_alloc_maygrow(buddy, size, false);
 }
 
+__weak
+int buddy_grow(struct buddy __arena *buddy, size_t nr_chunks)
+{
+	struct buddy_chunk __arena *chunk;
+	unsigned long flags;
+	size_t chunk_index;
+
+	for (chunk_index = zero; chunk_index < nr_chunks && can_loop; chunk_index++) {
+		chunk = buddy_chunk_get(buddy);
+		if (!chunk)
+			return -ENOMEM;
+
+		if (buddy_lock(buddy, flags)) {
+			bpf_arena_free_pages(&arena, chunk, BUDDY_CHUNK_PAGES);
+			return -ENOMEM;
+		}
+
+		chunk->next = buddy->first_chunk;
+		buddy->first_chunk = chunk;
+
+		buddy_unlock(buddy, flags);
+	}
+
+	return 0;
+}
+
 static __always_inline int buddy_free_unlocked(struct buddy __arena *buddy, u64 addr)
 {
 	struct buddy_header __arena *header, *buddy_header;
-- 
2.52.0