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Date: Thu, 15 Sep 2016 16:45:16 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: Andy Gospodarek <andy@...yhouse.net>
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
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.
>
>
>>
>> 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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