netdev - Re: [patch net-next v2 06/12] net: mroute: Check if rule is a default rule

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Date:   Mon, 25 Sep 2017 11:45:08 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Yunsheng Lin <linyunsheng@...wei.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, yotamg@...lanox.com,
        idosch@...lanox.com, mlxsw@...lanox.com,
        nikolay@...ulusnetworks.com, andrew@...n.ch
Subject: Re: [patch net-next v2 06/12] net: mroute: Check if rule is a
 default rule

Mon, Sep 25, 2017 at 03:28:21AM CEST, linyunsheng@...wei.com wrote:
>Hi, Jiri
>
>On 2017/9/25 1:22, Jiri Pirko wrote:
>> From: Yotam Gigi <yotamg@...lanox.com>
>> 
>> When the ipmr starts, it adds one default FIB rule that matches all packets
>> and sends them to the DEFAULT (multicast) FIB table. A more complex rule
>> can be added by user to specify that for a specific interface, a packet
>> should be look up at either an arbitrary table or according to the l3mdev
>> of the interface.
>> 
>> For drivers willing to offload the ipmr logic into a hardware but don't
>> want to offload all the FIB rules functionality, provide a function that
>> can indicate whether the FIB rule is the default multicast rule, thus only
>> one routing table is needed.
>> 
>> This way, a driver can register to the FIB notification chain, get
>> notifications about FIB rules added and trigger some kind of an internal
>> abort mechanism when a non default rule is added by the user.
>> 
>> Signed-off-by: Yotam Gigi <yotamg@...lanox.com>
>> Reviewed-by: Ido Schimmel <idosch@...lanox.com>
>> Signed-off-by: Jiri Pirko <jiri@...lanox.com>
>> ---
>>  include/linux/mroute.h |  7 +++++++
>>  net/ipv4/ipmr.c        | 10 ++++++++++
>>  2 files changed, 17 insertions(+)
>> 
>> diff --git a/include/linux/mroute.h b/include/linux/mroute.h
>> index 5566580..b072a84 100644
>> --- a/include/linux/mroute.h
>> +++ b/include/linux/mroute.h
>> @@ -5,6 +5,7 @@
>>  #include <linux/pim.h>
>>  #include <linux/rhashtable.h>
>>  #include <net/sock.h>
>> +#include <net/fib_rules.h>
>>  #include <net/fib_notifier.h>
>>  #include <uapi/linux/mroute.h>
>>  
>> @@ -19,6 +20,7 @@ int ip_mroute_getsockopt(struct sock *, int, char __user *, int __user *);
>>  int ipmr_ioctl(struct sock *sk, int cmd, void __user *arg);
>>  int ipmr_compat_ioctl(struct sock *sk, unsigned int cmd, void __user *arg);
>>  int ip_mr_init(void);
>> +bool ipmr_rule_default(const struct fib_rule *rule);
>>  #else
>>  static inline int ip_mroute_setsockopt(struct sock *sock, int optname,
>>  				       char __user *optval, unsigned int optlen)
>> @@ -46,6 +48,11 @@ static inline int ip_mroute_opt(int opt)
>>  {
>>  	return 0;
>>  }
>> +
>> +static inline bool ipmr_rule_default(const struct fib_rule *rule)
>> +{
>> +	return true;
>> +}
>>  #endif
>>  
>>  struct vif_device {
>> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
>> index 2a795d2..a714f55 100644
>> --- a/net/ipv4/ipmr.c
>> +++ b/net/ipv4/ipmr.c
>> @@ -320,6 +320,16 @@ static unsigned int ipmr_rules_seq_read(struct net *net)
>>  }
>>  #endif
>>  
>> +bool ipmr_rule_default(const struct fib_rule *rule)
>> +{
>> +#if IS_ENABLED(CONFIG_FIB_RULES)
>> +	return fib_rule_matchall(rule) && rule->table == RT_TABLE_DEFAULT;
>> +#else
>> +	return true;
>> +#endif
>
>In patch 02, You have the following, can you do the same for the above?
>+#ifdef CONFIG_IP_MROUTE
>+void ipmr_cache_free(struct mfc_cache *mfc_cache);
>+#else
>+static inline void ipmr_cache_free(struct mfc_cache *mfc_cache)
>+{
>+}
>+#endif

I don't believe this is necessary. The solution you described is often
used in headers. But here, I'm ok with the current code.


>
>> +}
>> +EXPORT_SYMBOL(ipmr_rule_default);
>> +
>>  static inline int ipmr_hash_cmp(struct rhashtable_compare_arg *arg,
>>  				const void *ptr)
>>  {
>> 
>