[ovs-dev] [patch v4 2/2] packets: ersapn_metadata header fixups.
William Tu
u9012063 at gmail.com
Fri May 25 00:22:37 UTC 2018
On Thu, May 24, 2018 at 2:16 PM, Ben Pfaff <blp at ovn.org> wrote:
> On Thu, May 24, 2018 at 12:08:31PM -0700, William Tu wrote:
>> On Thu, May 24, 2018 at 10:20 AM, Ben Pfaff <blp at ovn.org> wrote:
>> > On Thu, May 24, 2018 at 05:36:10AM -0700, William Tu wrote:
>> >> On Wed, May 23, 2018 at 7:13 PM, Darrell Ball <dlu998 at gmail.com> wrote:
>> >> > The struct erspan_metadata is updated to replace the 'version'
>> >> > placeholder with the erspan base hdr. Also, the erspan
>> >> > index is defined explicitly as ovs_16aligned_be32 to mirror
>> >> > its encoding.
>> >> > Changes to odp_util result from updating the erspan index
>> >> > type.
>> >> >
>> >> > CC: William Tu <u9012063 at gmail.com>
>> >> > Fixes: 068794b43f0e ("erspan: Add flow-based erspan options")
>> >> > Signed-off-by: Darrell Ball <dlu998 at gmail.com>
>> >> > ---
>> >> > lib/odp-util.c | 36 ++++++++++++++++++++----------------
>> >> > lib/packets.h | 6 +++---
>> >> > 2 files changed, 23 insertions(+), 19 deletions(-)
>> >> >
>> >> > diff --git a/lib/odp-util.c b/lib/odp-util.c
>> >> > index 105ac80..767281f 100644
>> >> > --- a/lib/odp-util.c
>> >> > +++ b/lib/odp-util.c
>> >> > @@ -2786,9 +2786,9 @@ odp_tun_key_from_attr__(const struct nlattr *attr, bool is_mask,
>> >> >
>> >> > memcpy(&opts, nl_attr_get(a), attr_len);
>> >> >
>> >> > - tun->erspan_ver = opts.version;
>> >> > + tun->erspan_ver = opts.bh.ver;
>> >> > if (tun->erspan_ver == 1) {
>> >> > - tun->erspan_idx = ntohl(opts.u.index);
>> >> > + tun->erspan_idx = ntohl(get_16aligned_be32(&opts.u.index));
>> >> > } else if (tun->erspan_ver == 2) {
>> >> > tun->erspan_dir = opts.u.md2.dir;
>> >> > tun->erspan_hwid = get_hwid(&opts.u.md2);
>> >> > @@ -2890,10 +2890,11 @@ tun_key_to_attr(struct ofpbuf *a, const struct flow_tnl *tun_key,
>> >> > !strcmp(tnl_type, "ip6erspan")) &&
>> >> > (tun_key->erspan_ver == 1 || tun_key->erspan_ver == 2)) {
>> >> > struct erspan_metadata opts;
>> >> > + memset(&opts, 0, sizeof opts);
>> >> >
>> >> > - opts.version = tun_key->erspan_ver;
>> >> > - if (opts.version == 1) {
>> >> > - opts.u.index = htonl(tun_key->erspan_idx);
>> >> > + opts.bh.ver = tun_key->erspan_ver;
>> >> > + if (opts.bh.ver == 1) {
>> >> > + put_16aligned_be32(&opts.u.index, htonl(tun_key->erspan_idx));
>> >> > } else {
>> >> > opts.u.md2.dir = tun_key->erspan_dir;
>> >> > set_hwid(&opts.u.md2, tun_key->erspan_hwid);
>> >> > @@ -3368,22 +3369,23 @@ format_odp_tun_erspan_opt(const struct nlattr *attr,
>> >> > opts = nl_attr_get(attr);
>> >> > mask = mask_attr ? nl_attr_get(mask_attr) : NULL;
>> >> >
>> >> > - ver = (uint8_t)opts->version;
>> >> > + ver = opts->bh.ver;
>> >> > if (mask) {
>> >> > - ver_ma = (uint8_t)mask->version;
>> >> > + ver_ma = mask->bh.ver;
>> >> > }
>> >> >
>> >> > format_u8u(ds, "ver", ver, mask ? &ver_ma : NULL, verbose);
>> >> >
>> >> > - if (opts->version == 1) {
>> >> > + if (opts->bh.ver == 1) {
>> >> > if (mask) {
>> >> > ds_put_format(ds, "idx=%#"PRIx32"/%#"PRIx32",",
>> >> > - ntohl(opts->u.index),
>> >> > - ntohl(mask->u.index));
>> >> > + ntohl(get_16aligned_be32(&opts->u.index)),
>> >> > + ntohl(get_16aligned_be32(&mask->u.index)));
>> >> > } else {
>> >> > - ds_put_format(ds, "idx=%#"PRIx32",", ntohl(opts->u.index));
>> >> > + ds_put_format(ds, "idx=%#"PRIx32",",
>> >> > + ntohl(get_16aligned_be32(&opts->u.index)));
>> >> > }
>> >> > - } else if (opts->version == 2) {
>> >> > + } else if (opts->bh.ver == 2) {
>> >> > dir = opts->u.md2.dir;
>> >> > hwid = opts->u.md2.hwid;
>> >> > if (mask) {
>> >> > @@ -4859,10 +4861,11 @@ scan_erspan_metadata(const char *s,
>> >> >
>> >> > if (!strncmp(s, ")", 1)) {
>> >> > s += 1;
>> >> > - key->version = ver;
>> >> > - key->u.index = htonl(idx);
>> >> > + memset(&key->bh, 0, sizeof key->bh);
>> >> > + key->bh.ver = ver;
>> >> > + put_16aligned_be32(&key->u.index, htonl(idx));
>> >> > if (mask) {
>> >> > - mask->u.index = htonl(idx_mask);
>> >> > + put_16aligned_be32(&mask->u.index, htonl(idx_mask));
>> >> > }
>> >> > }
>> >> > return s - s_base;
>> >> > @@ -4882,7 +4885,8 @@ scan_erspan_metadata(const char *s,
>> >> >
>> >> > if (!strncmp(s, ")", 1)) {
>> >> > s += 1;
>> >> > - key->version = ver;
>> >> > + memset(&key->bh, 0, sizeof key->bh);
>> >> > + key->bh.ver = ver;
>> >> > key->u.md2.hwid = hwid;
>> >> > key->u.md2.dir = dir;
>> >> > if (mask) {
>> >> > diff --git a/lib/packets.h b/lib/packets.h
>> >> > index 7645a9d..5c013a3 100644
>> >> > --- a/lib/packets.h
>> >> > +++ b/lib/packets.h
>> >> > @@ -1312,10 +1312,10 @@ struct erspan_md2 {
>> >> > };
>> >> >
>> >> > struct erspan_metadata {
>> >> > - int version;
>> >> > + struct erspan_base_hdr bh;
>> >> > union {
>> >> > - ovs_be32 index; /* Version 1 (type II)*/
>> >> > - struct erspan_md2 md2; /* Version 2 (type III) */
>> >> > + ovs_16aligned_be32 index; /* Version 1 (type II). */
>> >> > + struct erspan_md2 md2; /* Version 2 (type III). */
>> >> > } u;
>> >> > };
>> >> >
>> >> Thanks for the patch.
>> >>
>> >> We shouldn't change this header since struct erspan_metadata is exposed
>> >> from kernel's UAPI header. (see include/uapi/linux/erspan.h).
>> >> OVS kernel module expects this binary format.
>> >
>> > We often use different data structures in userspace and the kernel.
>> > This only changes the userspace one.
>> >
>> > It's a bad idea to use "int" for wire formats because its size can vary
>> > among platforms (although the Linux kernel does rely on it being 32
>> > bits, we don't make the same assumption in our userspace).
>> >
>>
>> the 'int version' here is not wire format. It is to determine version 1 or 2
>> so that the metadata mode tunnel device knows to whether use
>> ovs_be32 index or,
>> struct erspan_md2 md2 (which are wire format)
>>
>> > It's a bad idea to use "ovs_be32" in packet formats, in userspace,
>> > because packets aren't always aligned on 32-bit boundaries.
>>
>> I see. Then I think we should do:
>> @@ -1314,7 +1314,7 @@ struct erspan_md2 {
>> struct erspan_metadata {
>> int version;
>> union {
>> - ovs_be32 index; /* Version 1 (type II)*/
>> + ovs_16aligned_be32 index; /* Version 1 (type II)*/
>> struct erspan_md2 md2; /* Version 2 (type III) */
>> } u;
>> };
>
> OK, now I understand what's going on. This is only used to define the
> format of the OVS_TUNNEL_KEY_ATTR_ERSPAN_OPTS attribute. Since it's not
> a wire format at all, we don't need to use ovs_16aligned_be32 either,
> and an "int" is fine too.
>
> Since erspan_metadata is part of the kernel ABI, which is exposed via
> Netlink, it should normally be defined by including a kernel header
> rather than in packets.h, which normally just defines wire formats for
> things. Can we arrange for that to happen?
>
Sure.
> Thanks,
>
> Ben.
>
> Also, I guess that we could just use the data in-place:
>
Yes, thanks.
I will submit a separate patch to fix this.
William
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