Re: [PATCH net-next v2 2/3] selftests: net: rds: add getsockopt() conversion test

[Allison Henderson <achender@kernel.org>]

On Fri, 2026-06-05 at 03:31 -0700, Breno Leitao wrote:
> Add a kselftest that exercises the RDS getsockopt() paths converted to
> the getsockopt_iter() / sockopt_t callback:
> 
> - RDS_RECVERR and SO_RDS_TRANSPORT, which return their int value through
>   copy_to_iter() and report the written length in opt->optlen.
> 
> - RDS_INFO_*, which obtains the userspace buffer pages with
>   iov_iter_extract_pages() (including a non-zero starting page offset)
>   and lets the info producers copy the snapshot in under a spinlock.
> 
> Signed-off-by: Breno Leitao <leitao@debian.org>
Hi Breno,

This looks great, thanks for the updates.  I noticed this morning though that this 
patch has a conflict in the Makefile on the latest net-next.  Commit 6d05d3cb44c5
renames run.sh to rds_run.sh. So you'll need to rebase for this patch to apply cleanly.  

Also, since the cover letter mentions vibe coding on this patch, I checked
Documentation/process/coding-assistants.rst for AI assisted patch procedures.
Per the documentation, this patch should carry an Assisted-By tag that identifies the
model, eg:

Assisted-by: <tool>:<model-version>

Other than that, this patch looks good to me.  With the above fixed, you can add
my RVB:

Reviewed-by: Allison Henderson <achender@kernel.org>

Thanks!
Allison

> ---
>  tools/testing/selftests/net/rds/.gitignore   |   1 +
>  tools/testing/selftests/net/rds/Makefile     |   4 +
>  tools/testing/selftests/net/rds/getsockopt.c | 208 +++++++++++++++++++++++++++
>  3 files changed, 213 insertions(+)
> 
> diff --git a/tools/testing/selftests/net/rds/.gitignore b/tools/testing/selftests/net/rds/.gitignore
> index 1c6f04e2aa11..7ca4b1440f51 100644
> --- a/tools/testing/selftests/net/rds/.gitignore
> +++ b/tools/testing/selftests/net/rds/.gitignore
> @@ -1 +1,2 @@
>  include.sh
> +getsockopt
> diff --git a/tools/testing/selftests/net/rds/Makefile b/tools/testing/selftests/net/rds/Makefile
> index fe363be8e358..0700d8298eec 100644
> --- a/tools/testing/selftests/net/rds/Makefile
> +++ b/tools/testing/selftests/net/rds/Makefile
> @@ -5,6 +5,8 @@ all:
>  
>  TEST_PROGS := run.sh
>  
> +TEST_GEN_PROGS := getsockopt
> +
>  TEST_FILES := \
>  	include.sh \
>  	settings \
> @@ -16,4 +18,6 @@ EXTRA_CLEAN := \
>  	/tmp/rds_logs \
>  # end of EXTRA_CLEAN
>  
> +CFLAGS += $(KHDR_INCLUDES)
> +
>  include ../../lib.mk
> diff --git a/tools/testing/selftests/net/rds/getsockopt.c b/tools/testing/selftests/net/rds/getsockopt.c
> new file mode 100644
> index 000000000000..93ff252c69b8
> --- /dev/null
> +++ b/tools/testing/selftests/net/rds/getsockopt.c
> @@ -0,0 +1,208 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Exercise the RDS getsockopt() paths that were converted to the
> + * getsockopt_iter() / sockopt_t callback.
> + *
> + * Three distinct paths are covered:
> + *
> + *   - RDS_RECVERR and SO_RDS_TRANSPORT, which now return their int value
> + *     through copy_to_iter() and report the written length in opt->optlen.
> + *
> + *   - RDS_INFO_*, which pins the userspace buffer with
> + *     iov_iter_extract_pages() (including a non-zero starting page offset)
> + *     and lets the info producers memcpy the snapshot in under a spinlock.
> + *
> + * The kvec (in-kernel buffer) -> -EOPNOTSUPP path of rds_info_getsockopt()
> + * is not reachable from a userspace getsockopt() and so is not tested here.
> + */
> +#include <errno.h>
> +#include <stdint.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/mman.h>
> +#include <sys/socket.h>
> +#include <linux/rds.h>
> +
> +#include "../../kselftest_harness.h"
> +
> +#ifndef AF_RDS
> +#define AF_RDS 21
> +#endif
> +
> +FIXTURE(rds) {
> +	int fd;
> +};
> +
> +FIXTURE_SETUP(rds)
> +{
> +	self->fd = socket(AF_RDS, SOCK_SEQPACKET, 0);
> +	if (self->fd < 0)
> +		SKIP(return, "AF_RDS unavailable (errno %d) - load the rds module",
> +		     errno);
> +}
> +
> +FIXTURE_TEARDOWN(rds)
> +{
> +	if (self->fd >= 0)
> +		close(self->fd);
> +}
> +
> +/* RDS_RECVERR defaults to 0 and is reported back as a 4-byte int. */
> +TEST_F(rds, recverr_default)
> +{
> +	socklen_t len = sizeof(int);
> +	int val = 0xdeadbeef;
> +
> +	ASSERT_EQ(0, getsockopt(self->fd, SOL_RDS, RDS_RECVERR, &val, &len));
> +	EXPECT_EQ(sizeof(int), len);
> +	EXPECT_EQ(0, val);
> +}
> +
> +/* A value set via setsockopt() must be readable back unchanged. */
> +TEST_F(rds, recverr_set_get)
> +{
> +	socklen_t len = sizeof(int);
> +	int val = 1;
> +
> +	ASSERT_EQ(0, setsockopt(self->fd, SOL_RDS, RDS_RECVERR, &val, len));
> +
> +	val = 0;
> +	ASSERT_EQ(0, getsockopt(self->fd, SOL_RDS, RDS_RECVERR, &val, &len));
> +	EXPECT_EQ(sizeof(int), len);
> +	EXPECT_EQ(1, val);
> +}
> +
> +/* A buffer smaller than an int is rejected with EINVAL, not silently. */
> +TEST_F(rds, recverr_short_buffer)
> +{
> +	socklen_t len = sizeof(int) - 1;
> +	char buf[sizeof(int)];
> +
> +	EXPECT_EQ(-1, getsockopt(self->fd, SOL_RDS, RDS_RECVERR, buf, &len));
> +	EXPECT_EQ(EINVAL, errno);
> +}
> +
> +/* An unbound socket reports RDS_TRANS_NONE for SO_RDS_TRANSPORT. */
> +TEST_F(rds, transport_unbound)
> +{
> +	socklen_t len = sizeof(int);
> +	int val = 0;
> +
> +	ASSERT_EQ(0, getsockopt(self->fd, SOL_RDS, SO_RDS_TRANSPORT, &val,
> +				&len));
> +	EXPECT_EQ(sizeof(int), len);
> +	EXPECT_EQ(RDS_TRANS_NONE, (unsigned int)val);
> +}
> +
> +TEST_F(rds, transport_short_buffer)
> +{
> +	socklen_t len = sizeof(int) - 1;
> +	char buf[sizeof(int)];
> +
> +	EXPECT_EQ(-1, getsockopt(self->fd, SOL_RDS, SO_RDS_TRANSPORT, buf,
> +				 &len));
> +	EXPECT_EQ(EINVAL, errno);
> +}
> +
> +/*
> + * RDS_INFO_COUNTERS with a zero-length buffer is the "probe" call: it must
> + * fail with ENOSPC and report the required snapshot size in optlen.
> + */
> +TEST_F(rds, info_counters_probe)
> +{
> +	socklen_t len = 0;
> +
> +	EXPECT_EQ(-1, getsockopt(self->fd, SOL_RDS, RDS_INFO_COUNTERS, NULL,
> +				 &len));
> +	EXPECT_EQ(ENOSPC, errno);
> +	EXPECT_GT(len, 0);
> +	/* The snapshot is an array of fixed-size counter records. */
> +	EXPECT_EQ(0, len % (socklen_t)sizeof(struct rds_info_counter));
> +}
> +
> +/*
> + * A real snapshot into an unaligned userspace buffer exercises the
> + * iov_iter_extract_pages() path, including the non-zero offset0 handling
> + * that the patch reworked. Place the buffer at a non-page-aligned address
> + * spanning into the next page to make sure multi-page pinning works too.
> + */
> +TEST_F(rds, info_counters_snapshot)
> +{
> +	struct rds_info_counter *ctr;
> +	socklen_t need = 0, len;
> +	long pagesz = sysconf(_SC_PAGESIZE);
> +	size_t offset, map_len;
> +	unsigned int i, n;
> +	char *region, *buf;
> +	int ret;
> +
> +	/* Probe for the required size. */
> +	getsockopt(self->fd, SOL_RDS, RDS_INFO_COUNTERS, NULL, &need);
> +	ASSERT_GT(need, 0);
> +
> +	/*
> +	 * Place the buffer at a non-page-aligned offset that runs past the
> +	 * first page boundary, and size the mapping from the probed length so
> +	 * the test keeps working if the counter set grows.
> +	 */
> +	offset = pagesz - 64;
> +	map_len = ((offset + need + pagesz - 1) / pagesz) * pagesz;
> +
> +	region = mmap(NULL, map_len, PROT_READ | PROT_WRITE,
> +		      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> +	ASSERT_NE(MAP_FAILED, region);
> +
> +	buf = region + offset;
> +
> +	/*
> +	 * On success the RDS_INFO path returns the positive per-element size
> +	 * (lens.each) rather than 0, and writes the full snapshot length back
> +	 * into optlen.
> +	 */
> +	len = need;
> +	ret = getsockopt(self->fd, SOL_RDS, RDS_INFO_COUNTERS, buf, &len);
> +	ASSERT_GE(ret, 0) {
> +		TH_LOG("getsockopt snapshot failed: errno %d", errno);
> +	}
> +	EXPECT_EQ(sizeof(struct rds_info_counter), ret);
> +	EXPECT_EQ(need, len);
> +
> +	/* The counter names must be NUL-terminated, non-empty strings. */
> +	ctr = (struct rds_info_counter *)buf;
> +	n = len / sizeof(*ctr);
> +	ASSERT_GT(n, 0);
> +	for (i = 0; i < n; i++) {
> +		size_t namelen = strnlen((char *)ctr[i].name,
> +					 sizeof(ctr[i].name));
> +
> +		EXPECT_GT(namelen, 0);
> +		EXPECT_LT(namelen, sizeof(ctr[i].name));
> +	}
> +
> +	munmap(region, map_len);
> +}
> +
> +/*
> + * A non-zero but too-small buffer must report ENOSPC and the full required
> + * length, without corrupting memory past the buffer.
> + */
> +TEST_F(rds, info_counters_short_buffer)
> +{
> +	socklen_t need = 0, len;
> +	char small[sizeof(struct rds_info_counter)];
> +
> +	getsockopt(self->fd, SOL_RDS, RDS_INFO_COUNTERS, NULL, &need);
> +	ASSERT_GT(need, 0);
> +
> +	/* Ask with a buffer guaranteed smaller than the full snapshot. */
> +	if (need <= (socklen_t)sizeof(small))
> +		SKIP(return, "snapshot fits in one record; nothing to test");
> +
> +	len = 1; /* < sizeof(struct rds_info_counter) */
> +	EXPECT_EQ(-1, getsockopt(self->fd, SOL_RDS, RDS_INFO_COUNTERS, small,
> +				 &len));
> +	EXPECT_EQ(ENOSPC, errno);
> +	EXPECT_EQ(need, len);
> +}
> +
> +TEST_HARNESS_MAIN
>