Re: [PATCH bpf-next v1 5/8] selftests/bpf: Add test for io_uring BPF iterators

[Yonghong Song <yhs@fb.com>]

On 11/15/21 9:42 PM, Kumar Kartikeya Dwivedi wrote:
> This exercises the io_uring_buf and io_uring_file iterators, and tests
> sparse file sets as well.
> 
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: Pavel Begunkov <asml.silence@gmail.com>
> Cc: io-uring@vger.kernel.org
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> ---
>   .../selftests/bpf/prog_tests/bpf_iter.c       | 226 ++++++++++++++++++
>   .../selftests/bpf/progs/bpf_iter_io_uring.c   |  50 ++++
>   2 files changed, 276 insertions(+)
>   create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_io_uring.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> index 3e10abce3e5a..baf11fe2f88d 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> @@ -1,6 +1,9 @@
>   // SPDX-License-Identifier: GPL-2.0
>   /* Copyright (c) 2020 Facebook */
> +#include <sys/mman.h>
>   #include <test_progs.h>
> +#include <linux/io_uring.h>
> +
>   #include "bpf_iter_ipv6_route.skel.h"
>   #include "bpf_iter_netlink.skel.h"
>   #include "bpf_iter_bpf_map.skel.h"
> @@ -26,6 +29,7 @@
>   #include "bpf_iter_bpf_sk_storage_map.skel.h"
>   #include "bpf_iter_test_kern5.skel.h"
>   #include "bpf_iter_test_kern6.skel.h"
> +#include "bpf_iter_io_uring.skel.h"
>   
>   static int duration;
>   
> @@ -1239,6 +1243,224 @@ static void test_task_vma(void)
>   	bpf_iter_task_vma__destroy(skel);
>   }
>   
> +static int sys_io_uring_setup(u32 entries, struct io_uring_params *p)
> +{
> +	return syscall(__NR_io_uring_setup, entries, p);
> +}
> +
> +static int io_uring_register_bufs(int io_uring_fd, struct iovec *iovs, unsigned int nr)
> +{
> +	return syscall(__NR_io_uring_register, io_uring_fd,
> +		       IORING_REGISTER_BUFFERS, iovs, nr);
> +}
> +
> +static int io_uring_register_files(int io_uring_fd, int *fds, unsigned int nr)
> +{
> +	return syscall(__NR_io_uring_register, io_uring_fd,
> +		       IORING_REGISTER_FILES, fds, nr);
> +}
> +
> +static unsigned long long page_addr_to_pfn(unsigned long addr)
> +{
> +	int page_size = sysconf(_SC_PAGE_SIZE), fd, ret;
> +	unsigned long long pfn;
> +
> +	if (page_size < 0)
> +		return 0;
> +	fd = open("/proc/self/pagemap", O_RDONLY);
> +	if (fd < 0)
> +		return 0;
> +
> +	ret = pread(fd, &pfn, sizeof(pfn), (addr / page_size) * 8);
> +	close(fd);
> +	if (ret < 0)
> +		return 0;
> +	/* Bits 0-54 have PFN for non-swapped page */
> +	return pfn & 0x7fffffffffffff;
> +}
> +
> +void test_io_uring_buf(void)
> +{
> +	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
> +	char rbuf[4096], buf[4096] = "B\n";
> +	union bpf_iter_link_info linfo;
> +	struct bpf_iter_io_uring *skel;
> +	int ret, fd, i, len = 128;
> +	struct io_uring_params p;
> +	struct iovec iovs[8];
> +	int iter_fd;
> +	char *str;
> +
> +	opts.link_info = &linfo;
> +	opts.link_info_len = sizeof(linfo);
> +
> +	skel = bpf_iter_io_uring__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "bpf_iter_io_uring__open_and_load"))
> +		return;
> +
> +	for (i = 0; i < ARRAY_SIZE(iovs); i++) {
> +		iovs[i].iov_len	 = len;
> +		iovs[i].iov_base = mmap(NULL, len, PROT_READ | PROT_WRITE,
> +					MAP_ANONYMOUS | MAP_SHARED, -1, 0);
> +		if (iovs[i].iov_base == MAP_FAILED)
> +			goto end;
> +		len *= 2;
> +	}
> +
> +	memset(&p, 0, sizeof(p));
> +	fd = sys_io_uring_setup(1, &p);
> +	if (!ASSERT_GE(fd, 0, "io_uring_setup"))
> +		goto end;
> +
> +	linfo.io_uring.io_uring_fd = fd;
> +	skel->links.dump_io_uring_buf = bpf_program__attach_iter(skel->progs.dump_io_uring_buf,
> +								 &opts);
> +	if (!ASSERT_OK_PTR(skel->links.dump_io_uring_buf, "bpf_program__attach_iter"))
> +		goto end_close_fd;
> +
> +	ret = io_uring_register_bufs(fd, iovs, ARRAY_SIZE(iovs));
> +	if (!ASSERT_OK(ret, "io_uring_register_bufs"))
> +		goto end_close_fd;
> +
> +	/* "B\n" */
> +	len = 2;
> +	str = buf + len;
> +	for (int j = 0; j < ARRAY_SIZE(iovs); j++) {
> +		ret = snprintf(str, sizeof(buf) - len, "%d:0x%lx:%zu\n", j,
> +			       (unsigned long)iovs[j].iov_base,
> +			       iovs[j].iov_len);
> +		if (!ASSERT_GE(ret, 0, "snprintf") || !ASSERT_LT(ret, sizeof(buf) - len, "snprintf"))
> +			goto end_close_fd;
> +		len += ret;
> +		str += ret;
> +
> +		ret = snprintf(str, sizeof(buf) - len, "`-PFN for bvec[0]=%llu\n",
> +			       page_addr_to_pfn((unsigned long)iovs[j].iov_base));
> +		if (!ASSERT_GE(ret, 0, "snprintf") || !ASSERT_LT(ret, sizeof(buf) - len, "snprintf"))
> +			goto end_close_fd;
> +		len += ret;
> +		str += ret;
> +	}
> +
> +	ret = snprintf(str, sizeof(buf) - len, "E:%zu\n", ARRAY_SIZE(iovs));
> +	if (!ASSERT_GE(ret, 0, "snprintf") || !ASSERT_LT(ret, sizeof(buf) - len, "snprintf"))
> +		goto end_close_fd;
> +
> +	iter_fd = bpf_iter_create(bpf_link__fd(skel->links.dump_io_uring_buf));
> +	if (!ASSERT_GE(iter_fd, 0, "bpf_iter_create"))
> +		goto end_close_fd;
> +
> +	ret = read_fd_into_buffer(iter_fd, rbuf, sizeof(rbuf));
> +	if (!ASSERT_GT(ret, 0, "read_fd_into_buffer"))
> +		goto end_close_iter;
> +
> +	ASSERT_OK(strcmp(rbuf, buf), "compare iterator output");
> +
> +	puts("=== Expected Output ===");
> +	printf("%s", buf);
> +	puts("==== Actual Output ====");
> +	printf("%s", rbuf);
> +	puts("=======================");

Maybe you can do an actual comparison and use ASSERT_* macros to check 
result?

> +
> +end_close_iter:
> +	close(iter_fd);
> +end_close_fd:
> +	close(fd);
> +end:
> +	while (i--)
> +		munmap(iovs[i].iov_base, iovs[i].iov_len);
> +	bpf_iter_io_uring__destroy(skel);
> +}
> +
> +void test_io_uring_file(void)
> +{
> +	int reg_files[] = { [0 ... 7] = -1 };
> +	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
> +	char buf[4096] = "B\n", rbuf[4096] = {}, *str;
> +	union bpf_iter_link_info linfo = {};
> +	struct bpf_iter_io_uring *skel;
> +	int iter_fd, fd, len = 0, ret;
> +	struct io_uring_params p;
> +
> +	opts.link_info = &linfo;
> +	opts.link_info_len = sizeof(linfo);
> +
> +	skel = bpf_iter_io_uring__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "bpf_iter_io_uring__open_and_load"))
> +		return;
> +
> +	/* "B\n" */
> +	len = 2;
> +	str = buf + len;
> +	ret = snprintf(str, sizeof(buf) - len, "B\n");
> +	for (int i = 0; i < ARRAY_SIZE(reg_files); i++) {
> +		char templ[] = "/tmp/io_uringXXXXXX";
> +		const char *name, *def = "<none>";
> +
> +		/* create sparse set */
> +		if (i & 1) {
> +			name = def;
> +		} else {
> +			reg_files[i] = mkstemp(templ);
> +			if (!ASSERT_GE(reg_files[i], 0, templ))
> +				goto end_close_reg_files;
> +			name = templ;
> +			ASSERT_OK(unlink(name), "unlink");
> +		}
> +		ret = snprintf(str, sizeof(buf) - len, "%d:%s%s\n", i, name, name != def ? " (deleted)" : "");
> +		if (!ASSERT_GE(ret, 0, "snprintf") || !ASSERT_LT(ret, sizeof(buf) - len, "snprintf"))
> +			goto end_close_reg_files;
> +		len += ret;
> +		str += ret;
> +	}
> +
> +	ret = snprintf(str, sizeof(buf) - len, "E:%zu\n", ARRAY_SIZE(reg_files));
> +	if (!ASSERT_GE(ret, 0, "snprintf") || !ASSERT_LT(ret, sizeof(buf) - len, "snprintf"))
> +		goto end_close_reg_files;
> +
> +	memset(&p, 0, sizeof(p));
> +	fd = sys_io_uring_setup(1, &p);
> +	if (!ASSERT_GE(fd, 0, "io_uring_setup"))
> +		goto end_close_reg_files;
> +
> +	linfo.io_uring.io_uring_fd = fd;
> +	skel->links.dump_io_uring_file = bpf_program__attach_iter(skel->progs.dump_io_uring_file,
> +								  &opts);
> +	if (!ASSERT_OK_PTR(skel->links.dump_io_uring_file, "bpf_program__attach_iter"))
> +		goto end_close_fd;
> +
> +	iter_fd = bpf_iter_create(bpf_link__fd(skel->links.dump_io_uring_file));
> +	if (!ASSERT_GE(iter_fd, 0, "bpf_iter_create"))
> +		goto end;
> +
> +	ret = io_uring_register_files(fd, reg_files, ARRAY_SIZE(reg_files));
> +	if (!ASSERT_OK(ret, "io_uring_register_files"))
> +		goto end_iter_fd;
> +
> +	ret = read_fd_into_buffer(iter_fd, rbuf, sizeof(rbuf));
> +	if (!ASSERT_GT(ret, 0, "read_fd_into_buffer(iterator_fd, buf)"))
> +		goto end_iter_fd;
> +
> +	ASSERT_OK(strcmp(rbuf, buf), "compare iterator output");
> +
> +	puts("=== Expected Output ===");
> +	printf("%s", buf);
> +	puts("==== Actual Output ====");
> +	printf("%s", rbuf);
> +	puts("=======================");

The same as above.

> +end_iter_fd:
> +	close(iter_fd);
> +end_close_fd:
> +	close(fd);
> +end_close_reg_files:
> +	for (int i = 0; i < ARRAY_SIZE(reg_files); i++) {
> +		if (reg_files[i] != -1)
> +			close(reg_files[i]);
> +	}
> +end:
> +	bpf_iter_io_uring__destroy(skel);
> +}
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