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Date: Thu, 15 Sep 2016 10:47:40 -0400
From: Andy Gospodarek <andy@...yhouse.net>
To: Jiri Pirko <jiri@...nulli.us>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
David Miller <davem@...emloft.net>, idosch@...lanox.com,
eladr@...lanox.com, yotamg@...lanox.com, nogahf@...lanox.com,
ogerlitz <ogerlitz@...lanox.com>,
Roopa Prabhu <roopa@...ulusnetworks.com>,
nikolay@...ulusnetworks.com,
John Linville <linville@...driver.com>,
Thomas Graf <tgraf@...g.ch>, Scott Feldman <sfeldma@...il.com>,
ast@...mgrid.com, Eric Dumazet <edumazet@...gle.com>,
hannes@...essinduktion.org,
Florian Fainelli <f.fainelli@...il.com>,
dsa@...ulusnetworks.com, Jamal Hadi Salim <jhs@...atatu.com>,
vivien.didelot@...oirfairelinux.com, john.fastabend@...el.com,
andrew@...n.ch, ivecera@...hat.com
Subject: Re: [net-next,RFC,1/2] fib: introduce fib notification infrastructure
On Thu, Sep 15, 2016 at 10:45 AM, Jiri Pirko <jiri@...nulli.us> wrote:
> Thu, Sep 15, 2016 at 04:41:20PM CEST, andy@...yhouse.net wrote:
>>On Tue, Sep 6, 2016 at 8:01 AM, Jiri Pirko
>><andrew.gospodarek@...adcom.com> wrote:
>>> From: Jiri Pirko <jiri@...lanox.com>
>>>
>>> This allows to pass information about added/deleted fib entries to
>>> whoever is interested. This is done in a very similar way as devinet
>>> notifies address additions/removals.
>>
>>(Sorry for the delayed response here...)
>>
>>I had tried a slightly different approach, but this one also seems
>>reasonable and possibly better -- especially if this can be made more
>>generic and shared between ipv4 and ipv6 despite their inherent
>>differences.
>>
>>What I did differently was make a more ipv4-specific change to start
>>with that did this:
>>
>>+#define RTNH_F_MODIFIED (1 << 7) /* used for
>>internal kernel tracking */
>>+
>>+#define RTNH_F_COMPARE_MASK (RTNH_F_DEAD | \
>>+ RTNH_F_LINKDOWN | \
>>+ RTNH_F_MODIFIED) /* used as mask for
>>route comparisons */
>>
>>Then in various cases where the route was modified (fib_sync_up, etc),
>>I added this:
>>
>>+ nexthop_nh->nh_flags |= RTNH_F_MODIFIED;
>>
>>Checking for the modified flag was then done in fib_table_update().
>>This new function was a rewrite of fib_table_flush() and checks for
>>RTNH_F_MODIFIED were done there before calling switchdev infra and
>>then announce new routes if routes changed.
>>
>>The main issue I see right now is that neither userspace nor switchdev
>>are notified when a route flag changes. This needs to be resolved.
>>
>>I think this RFC is along the proper path to provide notification, but
>>I'm not sure that notification will happen when flags change (most
>>notably the LNKDOWN flag) and there are some other corner cases that
>>could probably be covered as well.
>>
>>I need to forward-port my patch from where it was to the latest
>>net-next and see if these cases I was concerned about were still an
>>issue. I'm happy to do that and see if we can put this all together
>>to fix a few of the outstanding issues.
>
> I believe that "modify" can be easily another fib event. Drivers can
> react accordingly. I'm close to sending v1 (hopefully tomorrow). I
> believe you can base your patchset on top of mine which saves you lot of
> time.
>
Sounds good -- looking forward to it. If you add this email on the
cc-list rather than the other one, I'll see it more quickly this time.
:-)
>
>>
>>
>>>
>>> Signed-off-by: Jiri Pirko <jiri@...lanox.com>
>>> ---
>>> include/net/ip_fib.h | 19 +++++++++++++++++++
>>> net/ipv4/fib_trie.c | 43 +++++++++++++++++++++++++++++++++++++++++++
>>> 2 files changed, 62 insertions(+)
>>>
>>> diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
>>> index 4079fc1..9ad7ba9 100644
>>> --- a/include/net/ip_fib.h
>>> +++ b/include/net/ip_fib.h
>>> @@ -22,6 +22,7 @@
>>> #include <net/fib_rules.h>
>>> #include <net/inetpeer.h>
>>> #include <linux/percpu.h>
>>> +#include <linux/notifier.h>
>>>
>>> struct fib_config {
>>> u8 fc_dst_len;
>>> @@ -184,6 +185,24 @@ __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh);
>>> #define FIB_RES_PREFSRC(net, res) ((res).fi->fib_prefsrc ? : \
>>> FIB_RES_SADDR(net, res))
>>>
>>> +struct fib_notifier_info {
>>> + u32 dst;
>>> + int dst_len;
>>> + struct fib_info *fi;
>>> + u8 tos;
>>> + u8 type;
>>> + u32 tb_id;
>>> + u32 nlflags;
>>> +};
>>> +
>>> +enum fib_event_type {
>>> + FIB_EVENT_TYPE_ADD,
>>> + FIB_EVENT_TYPE_DEL,
>>> +};
>>> +
>>> +int register_fib_notifier(struct notifier_block *nb);
>>> +int unregister_fib_notifier(struct notifier_block *nb);
>>> +
>>> struct fib_table {
>>> struct hlist_node tb_hlist;
>>> u32 tb_id;
>>> diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
>>> index e2ffc2a..19ec471 100644
>>> --- a/net/ipv4/fib_trie.c
>>> +++ b/net/ipv4/fib_trie.c
>>> @@ -73,6 +73,7 @@
>>> #include <linux/slab.h>
>>> #include <linux/export.h>
>>> #include <linux/vmalloc.h>
>>> +#include <linux/notifier.h>
>>> #include <net/net_namespace.h>
>>> #include <net/ip.h>
>>> #include <net/protocol.h>
>>> @@ -84,6 +85,36 @@
>>> #include <trace/events/fib.h>
>>> #include "fib_lookup.h"
>>>
>>> +static BLOCKING_NOTIFIER_HEAD(fib_chain);
>>> +
>>> +int register_fib_notifier(struct notifier_block *nb)
>>> +{
>>> + return blocking_notifier_chain_register(&fib_chain, nb);
>>> +}
>>> +EXPORT_SYMBOL(register_fib_notifier);
>>> +
>>> +int unregister_fib_notifier(struct notifier_block *nb)
>>> +{
>>> + return blocking_notifier_chain_unregister(&fib_chain, nb);
>>> +}
>>> +EXPORT_SYMBOL(unregister_fib_notifier);
>>> +
>>> +static int call_fib_notifiers(enum fib_event_type event_type, u32 dst,
>>> + int dst_len, struct fib_info *fi,
>>> + u8 tos, u8 type, u32 tb_id, u32 nlflags)
>>> +{
>>> + struct fib_notifier_info info = {
>>> + .dst = dst,
>>> + .dst_len = dst_len,
>>> + .fi = fi,
>>> + .tos = tos,
>>> + .type = type,
>>> + .tb_id = tb_id,
>>> + .nlflags = nlflags,
>>> + };
>>> + return blocking_notifier_call_chain(&fib_chain, event_type, &info);
>>> +}
>>> +
>>> #define MAX_STAT_DEPTH 32
>>>
>>> #define KEYLENGTH (8*sizeof(t_key))
>>> @@ -1190,6 +1221,10 @@ int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
>>> fib_release_info(fi_drop);
>>> if (state & FA_S_ACCESSED)
>>> rt_cache_flush(cfg->fc_nlinfo.nl_net);
>>> +
>>> + call_fib_notifiers(FIB_EVENT_TYPE_ADD, key, plen, fi,
>>> + new_fa->fa_tos, cfg->fc_type,
>>> + tb->tb_id, cfg->fc_nlflags);
>>> rtmsg_fib(RTM_NEWROUTE, htonl(key), new_fa, plen,
>>> tb->tb_id, &cfg->fc_nlinfo, NLM_F_REPLACE);
>>>
>>> @@ -1241,6 +1276,8 @@ int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
>>> tb->tb_num_default++;
>>>
>>> rt_cache_flush(cfg->fc_nlinfo.nl_net);
>>> + call_fib_notifiers(FIB_EVENT_TYPE_ADD, key, plen, fi, tos,
>>> + cfg->fc_type, tb->tb_id, cfg->fc_nlflags);
>>> rtmsg_fib(RTM_NEWROUTE, htonl(key), new_fa, plen, new_fa->tb_id,
>>> &cfg->fc_nlinfo, nlflags);
>>> succeeded:
>>> @@ -1542,6 +1579,8 @@ int fib_table_delete(struct fib_table *tb, struct fib_config *cfg)
>>> switchdev_fib_ipv4_del(key, plen, fa_to_delete->fa_info, tos,
>>> cfg->fc_type, tb->tb_id);
>>>
>>> + call_fib_notifiers(FIB_EVENT_TYPE_DEL, key, plen, fa_to_delete->fa_info,
>>> + tos, cfg->fc_type, tb->tb_id, 0);
>>> rtmsg_fib(RTM_DELROUTE, htonl(key), fa_to_delete, plen, tb->tb_id,
>>> &cfg->fc_nlinfo, 0);
>>>
>>> @@ -1857,6 +1896,10 @@ int fib_table_flush(struct fib_table *tb)
>>> switchdev_fib_ipv4_del(n->key, KEYLENGTH - fa->fa_slen,
>>> fi, fa->fa_tos, fa->fa_type,
>>> tb->tb_id);
>>> + call_fib_notifiers(FIB_EVENT_TYPE_DEL, n->key,
>>> + KEYLENGTH - fa->fa_slen,
>>> + fi, fa->fa_tos, fa->fa_type,
>>> + tb->tb_id, 0);
>>> hlist_del_rcu(&fa->fa_list);
>>> fib_release_info(fa->fa_info);
>>> alias_free_mem_rcu(fa);
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