linux-kernel - [PATCH] selftests/bpf: Fix kmem

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Message-ID: <20250428180256.1482899-1-tjmercier@google.com>
Date: Mon, 28 Apr 2025 18:02:54 +0000
From: "T.J. Mercier" <tjmercier@...gle.com>
To: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau <martin.lau@...ux.dev>, 
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
	Jiri Olsa <jolsa@...nel.org>, Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>, 
	Namhyung Kim <namhyung@...nel.org>
Cc: "T.J. Mercier" <tjmercier@...gle.com>, bpf@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] selftests/bpf: Fix kmem_cache iterator draining

The closing parentheses around the read syscall is misplaced, causing
single byte reads from the iterator instead of buf sized reads. While
the end result is the same, many more read calls than necessary are
performed.

$ tools/testing/selftests/bpf/vmtest.sh  "./test_progs -t kmem_cache_iter"
145/1   kmem_cache_iter/check_task_struct:OK
145/2   kmem_cache_iter/check_slabinfo:OK
145/3   kmem_cache_iter/open_coded_iter:OK
145     kmem_cache_iter:OK
Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED

Fixes: a496d0cdc84d ("selftests/bpf: Add a test for kmem_cache_iter")
Signed-off-by: T.J. Mercier <tjmercier@...gle.com>
---
 tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c
index 8e13a3416a21..1de14b111931 100644
--- a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c
@@ -104,7 +104,7 @@ void test_kmem_cache_iter(void)
 		goto destroy;
 
 	memset(buf, 0, sizeof(buf));
-	while (read(iter_fd, buf, sizeof(buf) > 0)) {
+	while (read(iter_fd, buf, sizeof(buf)) > 0) {
 		/* Read out all contents */
 		printf("%s", buf);
 	}

base-commit: b4432656b36e5cc1d50a1f2dc15357543add530e
-- 
2.49.0.906.g1f30a19c02-goog