Subject: Re: [PATCH] net/hsr: Add support for the High-availability Seamless Redundancy protocol (HSRv0)

From: Arvid Brodin <[email-masked]>
Date: Tue, 25 Jun 2013 23:16:40 +0200

On 2013-06-24 20:16, Joe Perches wrote:
> On Mon, 2013-06-24 at 18:43 +0200, Arvid Brodin wrote:
>> High-availability Seamless Redundancy ("HSR") provides instant failover
>> redundancy for Ethernet networks. It requires a special network topology where
>> all nodes are connected in a ring (each node having two physical network
>> interfaces). It is suited for applications that demand high availability and
>> very short reaction time.
> 
> trivia:
> 
> You should probably use checkpatch.pl --strict for files in net.
> It will suggest aligning arguments in the more common net style.

Does this mean I should also remove spaces after casts (IMO this would reduce readability
somewhat)?

>>  net/hsr/hsr_device.h          |  30 +++
>>  net/hsr/hsr_framereg.h        |  54 ++++
>>  net/hsr/hsr_main.h            | 167 ++++++++++++
>>  net/hsr/hsr_netlink.h         |  74 ++++++
> 
> Maybe some of these .h files should go into include/net/...
> 
> A future version of checkpatch may read all the include
> files and exempt any CamelCase defines/typedefs/functions
> from CamelCase warnings.

I cannot judge if these files should go into include/net/ or not. Where can I get a final
say on this?

Some of the definitions in hsr_netlink.h are needed by userspace tools that want to listen
for ring errors etc from the HSR driver, so it would be a good thing if this file could be
part of the kernel headers install. How can I accomplish this?

>> +	if ((skb->protocol != htons(ETH_P_PRP)) ||
>> +			(hsr_ethhdr->ethhdr.h_proto != htons(ETH_P_PRP))) {
> 
> Please align indents after the appropriate open parenthesis. 
> 
> 	if (foo ||
> 	    bar) {
> 
>> +bool is_hsr_master(struct net_device *dev)
>> +{
>> +	if (!dev) {
>> +		WARN_ON_ONCE(1);
>> +		return 0;
>> +	}
>> +	if (!dev->netdev_ops) {
>> +		WARN_ON_ONCE(1);
>> +		return 0;
>> +	}
> 
> probably better to combine and give a textual reason

Or perhaps better to remove them altogether? I guess you could call them debug statements...

>> diff --git a/net/hsr/hsr_main.h b/net/hsr/hsr_main.h
> []
>> +#define HSR_LIFE_CHECK_INTERVAL		 2000 /* ms */
>> +#define HSR_NODE_FORGET_TIME		60000 /* ms */
>> +#define HSR_ANNOUNCE_INTERVAL		  100 /* ms */
> 
> Odd alignment

Only because of the plus chars added by diff. :)

>> diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c
> []
>> +static const struct nla_policy hsr_genl_policy[HSR_A_MAX + 1] = {
>> +	[HSR_A_NODE_ADDR] = { .type = NLA_BINARY, .len = ETH_ALEN },
>> +	[HSR_A_NODE_ADDR_B] = { .type = NLA_BINARY, .len = ETH_ALEN },
>> +	[HSR_A_IFINDEX] = { .type = NLA_U32 },
>> +	[HSR_A_IF1_AGE] = { .type = NLA_U32 }, /* Actually signed 32-bit */
>> +	[HSR_A_IF2_AGE] = { .type = NLA_U32 }, /* Actually signed 32-bit */
> 
> Why not use NLA_S32?

We need the code to work on older kernels as well, where NLA_S32 does not exist. Actually,
these values never become negative with the current code. During development we returned a
negative value to mean "out of range" but we have switched to INT_MAX instead. So perhaps
it's best just to remove these comments?

-- 
Arvid Brodin | Consultant (Linux)
T: +46-8-56254286 | M: +46-70-9714286 | [email-masked]
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