On 3/7/24 18:08, Eric Garver wrote:
> Kernel support has been added for this action. As such, we need to probe
> the datapath for support.
> 
> Signed-off-by: Eric Garver <[email protected]>
> ---
>  include/linux/openvswitch.h |  2 +-
>  lib/dpif.c                  |  6 ---
>  lib/dpif.h                  |  1 -
>  ofproto/ofproto-dpif.c      | 89 +++++++++++++++++++++++++++++++++++--
>  ofproto/ofproto-dpif.h      |  4 +-
>  5 files changed, 89 insertions(+), 13 deletions(-)

Not a full review, but a few comments inline.

This patch will need to remove the OVS_UNUSED mark.

> 
> diff --git a/include/linux/openvswitch.h b/include/linux/openvswitch.h
> index a265e05ad253..fce6456f47c8 100644
> --- a/include/linux/openvswitch.h
> +++ b/include/linux/openvswitch.h
> @@ -1086,11 +1086,11 @@ enum ovs_action_attr {
>       OVS_ACTION_ATTR_CHECK_PKT_LEN, /* Nested OVS_CHECK_PKT_LEN_ATTR_*. */
>       OVS_ACTION_ATTR_ADD_MPLS,     /* struct ovs_action_add_mpls. */
>       OVS_ACTION_ATTR_DEC_TTL,      /* Nested OVS_DEC_TTL_ATTR_*. */
> +     OVS_ACTION_ATTR_DROP,         /* u32 xlate_error. */
>  
>  #ifndef __KERNEL__
>       OVS_ACTION_ATTR_TUNNEL_PUSH,   /* struct ovs_action_push_tnl*/
>       OVS_ACTION_ATTR_TUNNEL_POP,    /* u32 port number. */
> -     OVS_ACTION_ATTR_DROP,          /* u32 xlate_error. */
>       OVS_ACTION_ATTR_LB_OUTPUT,     /* u32 bond-id. */
>  #endif
>       __OVS_ACTION_ATTR_MAX,        /* Nothing past this will be accepted
> diff --git a/lib/dpif.c b/lib/dpif.c
> index 0f480bec48d0..28fa40879655 100644
> --- a/lib/dpif.c
> +++ b/lib/dpif.c
> @@ -1934,12 +1934,6 @@ dpif_supports_tnl_push_pop(const struct dpif *dpif)
>      return dpif_is_netdev(dpif);
>  }
>  
> -bool
> -dpif_supports_explicit_drop_action(const struct dpif *dpif)
> -{
> -    return dpif_is_netdev(dpif);
> -}

I'm not sure if calling dpif_is_netdev() from ofproto-dpif layer
is a good idea.  Maybe add the hwol check into this function and
rename it into dpif_may_support_explicit_drop_action()?

And call this from two places in ofproto-dpif.c below.

What do you think?

> -
>  bool
>  dpif_supports_lb_output_action(const struct dpif *dpif)
>  {
> diff --git a/lib/dpif.h b/lib/dpif.h
> index 0f2dc2ef3c55..8dc5da45b3ef 100644
> --- a/lib/dpif.h
> +++ b/lib/dpif.h
> @@ -940,7 +940,6 @@ int dpif_get_pmds_for_port(const struct dpif * dpif, 
> odp_port_t port_no,
>  
>  char *dpif_get_dp_version(const struct dpif *);
>  bool dpif_supports_tnl_push_pop(const struct dpif *);
> -bool dpif_supports_explicit_drop_action(const struct dpif *);
>  bool dpif_synced_dp_layers(struct dpif *);
>  
>  /* Log functions. */
> diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
> index 4e22ee0e8045..b9d35d6efa62 100644
> --- a/ofproto/ofproto-dpif.c
> +++ b/ofproto/ofproto-dpif.c
> @@ -72,6 +72,8 @@
>  #include "util.h"
>  #include "uuid.h"
>  #include "vlan-bitmap.h"
> +#include "dpif-netdev.h"
> +#include "netdev-offload.h"

Moving the checks back to dpif.c will get rid of these strange
includes.

>  
>  VLOG_DEFINE_THIS_MODULE(ofproto_dpif);
>  
> @@ -221,6 +223,8 @@ static void ct_zone_config_init(struct dpif_backer 
> *backer);
>  static void ct_zone_config_uninit(struct dpif_backer *backer);
>  static void ct_zone_timeout_policy_sweep(struct dpif_backer *backer);
>  static void ct_zone_limits_commit(struct dpif_backer *backer);
> +static bool check_drop_action(struct dpif_backer *backer);
> +static bool recheck_support_explicit_drop_action(struct dpif_backer *backer);
>  
>  static inline struct ofproto_dpif *
>  ofproto_dpif_cast(const struct ofproto *ofproto)
> @@ -391,6 +395,10 @@ type_run(const char *type)
>          udpif_set_threads(backer->udpif, n_handlers, n_revalidators);
>      }
>  
> +    if (recheck_support_explicit_drop_action(backer)) {
> +        backer->need_revalidate = REV_RECONFIGURE;
> +    }
> +
>      if (backer->need_revalidate) {
>          struct ofproto_dpif *ofproto;
>          struct simap_node *node;
> @@ -807,6 +815,7 @@ open_dpif_backer(const char *type, struct dpif_backer 
> **backerp)
>  
>      shash_add(&all_dpif_backers, type, backer);
>  
> +    atomic_init(&backer->rt_support.explicit_drop_action, false);
>      check_support(backer);
>      atomic_count_init(&backer->tnl_count, 0);
>  
> @@ -855,7 +864,10 @@ ovs_native_tunneling_is_on(struct ofproto_dpif *ofproto)
>  bool
>  ovs_explicit_drop_action_supported(struct ofproto_dpif *ofproto)
>  {
> -    return ofproto->backer->rt_support.explicit_drop_action;
> +    bool value;
> +    atomic_read_relaxed(&ofproto->backer->rt_support.explicit_drop_action,
> +                        &value);
> +    return value;
>  }
>  
>  bool
> @@ -1379,6 +1391,43 @@ check_ct_timeout_policy(struct dpif_backer *backer)
>      return !error;
>  }
>  
> +/* Tests whether backer's datapath supports the OVS_ACTION_ATTR_DROP action. 
> */
> +static bool
> +check_drop_action(struct dpif_backer *backer)
> +{
> +    struct odputil_keybuf keybuf;
> +    uint8_t actbuf[NL_A_U32_SIZE];
> +    struct ofpbuf actions;
> +    struct ofpbuf key;
> +    struct flow flow;
> +    bool supported;
> +    bool hw_offload;
> +
> +    struct odp_flow_key_parms odp_parms = {
> +        .flow = &flow,
> +        .probe = true,
> +    };
> +
> +    memset(&flow, 0, sizeof flow);
> +    ofpbuf_use_stack(&key, &keybuf, sizeof keybuf);
> +    odp_flow_key_from_flow(&odp_parms, &key);
> +
> +    ofpbuf_use_stack(&actions, &actbuf, sizeof actbuf);
> +    nl_msg_put_u32(&actions, OVS_ACTION_ATTR_DROP, XLATE_OK);
> +
> +    supported = dpif_probe_feature(backer->dpif, "drop", &key, &actions, 
> NULL);
> +
> +    /* TC does not support offloading this action. */
> +    hw_offload = netdev_is_flow_api_enabled() && 
> !dpif_is_netdev(backer->dpif);
> +
> +    VLOG_INFO("%s: Datapath %s drop action%s", dpif_name(backer->dpif),

s/drop action/explicit drop action/

Otherwise it may look misleading in the log as flow dumps do show
'drop' actions.

> +              (supported) ? "supports" : "does not support",
> +              (hw_offload) ? ", but not enabled due to hardware offload 
> being "
> +                             "enabled" : "");

May skip the 'being enabled' part.

> +
> +    return supported && !hw_offload;
> +}
> +
>  /* Tests whether 'backer''s datapath supports the all-zero SNAT case. */
>  static bool
>  dpif_supports_ct_zero_snat(struct dpif_backer *backer)
> @@ -1647,8 +1696,8 @@ check_support(struct dpif_backer *backer)
>      backer->rt_support.max_hash_alg = check_max_dp_hash_alg(backer);
>      backer->rt_support.check_pkt_len = check_check_pkt_len(backer);
>      backer->rt_support.ct_timeout = check_ct_timeout_policy(backer);
> -    backer->rt_support.explicit_drop_action =
> -        dpif_supports_explicit_drop_action(backer->dpif);
> +    atomic_store_relaxed(&backer->rt_support.explicit_drop_action,
> +                         check_drop_action(backer));
>      backer->rt_support.lb_output_action =
>          dpif_supports_lb_output_action(backer->dpif);
>      backer->rt_support.ct_zero_snat = dpif_supports_ct_zero_snat(backer);
> @@ -1665,6 +1714,36 @@ check_support(struct dpif_backer *backer)
>      backer->rt_support.odp.nd_ext = check_nd_extensions(backer);
>  }
>  
> +/* For TC, if vswitchd started with other_config:hw-offload set to "false", 
> and
> + * the configuration is now "true", then we need to re-probe datapath support
> + * for the "drop" action. */
> +static bool
> +recheck_support_explicit_drop_action(struct dpif_backer *backer) {

'{' should be on a new line.

> +    bool explicit_drop_action;
> +
> +    atomic_read_relaxed(&backer->rt_support.explicit_drop_action,
> +                        &explicit_drop_action);
> +
> +    if (explicit_drop_action
> +        && netdev_is_flow_api_enabled() && !dpif_is_netdev(backer->dpif)) {
> +        bool new_explicit_drop_action = check_drop_action(backer);
> +
> +        if (!new_explicit_drop_action) {
> +            atomic_compare_exchange_strong_relaxed(
> +                                   &backer->rt_support.explicit_drop_action,
> +                                   &explicit_drop_action,
> +                                   new_explicit_drop_action);
> +            /* If the cmpx fails, it means the value changed to false in a
> +             * different thread. As such, we still want to trigger a
> +             * reconfigure.
> +             */

This function should not be called in parallel, so atomic exchange
may be unnecessary.  It should be fine to just write it unconditionally
and return the new value.

> +            return true;
> +        }
> +    }
> +
> +    return false;
> +}
> +
>  static int
>  construct(struct ofproto *ofproto_)
>  {
> @@ -5706,6 +5785,7 @@ ct_zone_limit_protection_update(const char 
> *datapath_type, bool protected)
>  static void
>  get_datapath_cap(const char *datapath_type, struct smap *cap)
>  {
> +    bool explicit_drop_action;
>      struct dpif_backer_support *s;
>      struct dpif_backer *backer = shash_find_data(&all_dpif_backers,
>                                                   datapath_type);
> @@ -5741,8 +5821,9 @@ get_datapath_cap(const char *datapath_type, struct smap 
> *cap)
>      smap_add_format(cap, "max_hash_alg", "%"PRIuSIZE, s->max_hash_alg);
>      smap_add(cap, "check_pkt_len", s->check_pkt_len ? "true" : "false");
>      smap_add(cap, "ct_timeout", s->ct_timeout ? "true" : "false");
> +    atomic_read_relaxed(&s->explicit_drop_action, &explicit_drop_action);
>      smap_add(cap, "explicit_drop_action",
> -             s->explicit_drop_action ? "true" :"false");
> +             explicit_drop_action ? "true" :"false");
>      smap_add(cap, "lb_output_action", s->lb_output_action ? "true" : 
> "false");
>      smap_add(cap, "ct_zero_snat", s->ct_zero_snat ? "true" : "false");
>      smap_add(cap, "add_mpls", s->add_mpls ? "true" : "false");
> diff --git a/ofproto/ofproto-dpif.h b/ofproto/ofproto-dpif.h
> index 92d33aa64709..d33f73df8aed 100644
> --- a/ofproto/ofproto-dpif.h
> +++ b/ofproto/ofproto-dpif.h
> @@ -51,6 +51,7 @@
>  #include "hmapx.h"
>  #include "odp-util.h"
>  #include "id-pool.h"
> +#include "ovs-atomic.h"
>  #include "ovs-thread.h"
>  #include "ofproto-provider.h"
>  #include "util.h"
> @@ -202,7 +203,8 @@ struct group_dpif *group_dpif_lookup(struct ofproto_dpif 
> *,
>      DPIF_SUPPORT_FIELD(bool, ct_timeout, "Conntrack timeout policy")        \
>                                                                              \
>      /* True if the datapath supports explicit drop action. */               \
> -    DPIF_SUPPORT_FIELD(bool, explicit_drop_action, "Explicit Drop action")  \
> +    DPIF_SUPPORT_FIELD(atomic_bool, explicit_drop_action,                   \
> +                       "Explicit Drop action")                              \
>                                                                              \
>      /* True if the datapath supports balance_tcp optimization */            \
>      DPIF_SUPPORT_FIELD(bool, lb_output_action, "Optimized Balance TCP mode")\

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