Re: [PATCH v5 bpf-next 11/11] bpf: Test BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.

[Kuniyuki Iwashima]

From:   Martin KaFai Lau <kafai@xxxxxx>
Date:   Fri, 14 May 2021 19:05:15 -0700
> On Mon, May 10, 2021 at 12:44:33PM +0900, Kuniyuki Iwashima wrote:
> > diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
> > index 12ee40284da0..2060bc122c53 100644
> [ ... ]
> 
> > +static int setup_fastopen(char *buf, int size, int *saved_len, bool restore)
> > +{
> > +	int err = 0, fd, len;
> > +
> > +	fd = open("/proc/sys/net/ipv4/tcp_fastopen", O_RDWR);
> > +	if (!ASSERT_NEQ(fd, -1, "open"))
> > +		return -1;
> > +
> > +	if (restore) {
> > +		len = write(fd, buf, *saved_len);
> > +		if (!ASSERT_EQ(len, *saved_len, "write - restore"))
> > +			err = -1;
> > +	} else {
> > +		*saved_len = read(fd, buf, size);
> > +		if (!ASSERT_GE(*saved_len, 1, "read")) {
> > +			err = -1;
> > +			goto close;
> > +		}
> > +
> > +		err = lseek(fd, 0, SEEK_SET);
> > +		if (!ASSERT_OK(err, "lseek"))
> > +			goto close;
> > +
> > +		/* (TFO_CLIENT_ENABLE | TFO_SERVER_ENABLE) */
> > +		len = write(fd, "3", 1);
> > +		if (!ASSERT_EQ(len, 1, "write - setup"))
> Is it to trigger the tcp_try_fastopen() case?
> I am not sure it is enough.  At least, I think not for the
> very first connection before the cookie is saved.
> The second run of the test may be able to trigger it.
> 
> setsockopt(TCP_FASTOPEN_NO_COOKIE) or another value in the
> "/proc/sys/net/ipv4/tcp_fastopen" (ip-sysctl.rst) may be
> needed.

Ah, right. I missed that point while testing in the same host.
TFO should be always forced without cookies.


> 
> > +			err = -1;
> > +	}
> > +
> > +close:
> > +	close(fd);
> > +
> > +	return err;
> > +}
> > +
> [ ... ]
> 
> > diff --git a/tools/testing/selftests/bpf/progs/test_migrate_reuseport.c b/tools/testing/selftests/bpf/progs/test_migrate_reuseport.c
> > new file mode 100644
> > index 000000000000..72978b5d1fcb
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/test_migrate_reuseport.c
> > @@ -0,0 +1,67 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Check if we can migrate child sockets.
> > + *
> > + *   1. If reuse_md->migrating_sk is NULL (SYN packet),
> > + *        return SK_PASS without selecting a listener.
> > + *   2. If reuse_md->migrating_sk is not NULL (socket migration),
> > + *        select a listener (reuseport_map[migrate_map[cookie]])
> > + *
> > + * Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxxxx>
> > + */
> > +
> > +#include <stddef.h>
> > +#include <linux/bpf.h>
> > +#include <bpf/bpf_helpers.h>
> > +
> > +struct {
> > +	__uint(type, BPF_MAP_TYPE_REUSEPORT_SOCKARRAY);
> > +	__uint(max_entries, 256);
> > +	__type(key, int);
> > +	__type(value, __u64);
> > +} reuseport_map SEC(".maps");
> > +
> > +struct {
> > +	__uint(type, BPF_MAP_TYPE_HASH);
> > +	__uint(max_entries, 256);
> > +	__type(key, __u64);
> > +	__type(value, int);
> > +} migrate_map SEC(".maps");
> > +
> > +int migrated_at_close SEC(".data");
> > +int migrated_at_send_synack SEC(".data");
> > +int migrated_at_recv_ack SEC(".data");
> int migrated_at_close = 0;
> int migrated_at_send_synack = 0;
> int migrated_at_recv_ack = 0;
> 
> and then use skel->bss->migrated_at_* in migrate_reuseport.c.

I'll fix them.

Thank you.