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@google.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
On Mon, Apr 28, 2025 at 11:03 AM T.J. Mercier tjmercier@google.com wrote:
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@google.com
Acked-by: Song Liu song@kernel.org
Hello,
On Mon, Apr 28, 2025 at 06:02:54PM +0000, T.J. Mercier wrote:
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@google.com
Oops, thanks for fixing this.
Acked-by: Namhyung Kim namhyung@kernel.org
Thanks, Namhyung
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
On Mon, Apr 28, 2025 at 1:06 PM Namhyung Kim namhyung@kernel.org wrote:
Hello,
On Mon, Apr 28, 2025 at 06:02:54PM +0000, T.J. Mercier wrote:
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@google.com
Oops, thanks for fixing this.
Acked-by: Namhyung Kim namhyung@kernel.org
Thanks, Namhyung
No worries, thanks! It's been helpful reading through this code.
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
Hello:
This patch was applied to bpf/bpf-next.git (master) by Martin KaFai Lau martin.lau@kernel.org:
On Mon, 28 Apr 2025 18:02:54 +0000 you wrote:
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
[...]
Here is the summary with links: - selftests/bpf: Fix kmem_cache iterator draining https://git.kernel.org/bpf/bpf-next/c/38d976c32d85
You are awesome, thank you!
linux-kselftest-mirror@lists.linaro.org
-
Namhyung Kim -
patchwork-bot+netdevbpf＠kernel.org -
Song Liu -
T.J. Mercier