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Date: Tue, 6 Aug 2013 21:56:37 +0200
From: Michael Tuexen <Michael.Tuexen@...chi.franken.de>
To: Vlad Yasevich <vyasevich@...il.com>
Cc: Daniel Borkmann <dborkman@...hat.com>, davem@...emloft.net,
netdev@...r.kernel.org, linux-sctp@...r.kernel.org
Subject: Re: [PATCH net-next 1/2] net: sctp: convert sctp_checksum_disable module param into sctp sysctl
On Aug 6, 2013, at 9:31 PM, Vlad Yasevich <vyasevich@...il.com> wrote:
> On 08/06/2013 03:18 PM, Daniel Borkmann wrote:
>> Get rid of the last module parameter for SCTP and make this
>> configurable via sysctl for SCTP like all the rest of SCTP's
>> configuration knobs.
>>
>
> But this isn't like the rest of the sctp knobs. Disabling this violates the base protocol and we don't really want to encourage
> people to do this.
>
> There was a long discussion about it back in 2009 when the original
> patch was submitted that proposed a sysctl. Nothing has changed since
> then to convince me that this sysctl would be a good idea.
I agree with Vlad. In FreeBSD this is only a compile time flag
used at the time where no checksum offloading was available
and during research work people wanted to know how the
performance would be when it is available.
Since we have now these nics, not sure if it makes sense
to keep it configurable at all...
Best regards
Michael
>
> -vlad
>
>> Signed-off-by: Daniel Borkmann <dborkman@...hat.com>
>> ---
>> Documentation/networking/ip-sysctl.txt | 8 ++++++++
>> include/net/netns/sctp.h | 3 +++
>> include/net/sctp/structs.h | 5 -----
>> net/sctp/input.c | 4 ++--
>> net/sctp/output.c | 5 ++++-
>> net/sctp/protocol.c | 5 +++--
>> net/sctp/sysctl.c | 10 +++++++++-
>> 7 files changed, 29 insertions(+), 11 deletions(-)
>>
>> diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
>> index 36be26b..6f5b813 100644
>> --- a/Documentation/networking/ip-sysctl.txt
>> +++ b/Documentation/networking/ip-sysctl.txt
>> @@ -1507,6 +1507,14 @@ sack_timeout - INTEGER
>>
>> Default: 200
>>
>> +checksum_disable - BOOLEAN
>> + Disable SCTP checksum computing and verification for debugging purpose.
>> +
>> + 1: Disable checksumming
>> + 0: Enable checksumming
>> +
>> + Default: 0
>> +
>> valid_cookie_life - INTEGER
>> The default lifetime of the SCTP cookie (in milliseconds). The cookie
>> is used during association establishment.
>> diff --git a/include/net/netns/sctp.h b/include/net/netns/sctp.h
>> index 3573a81..ebfdf1e 100644
>> --- a/include/net/netns/sctp.h
>> +++ b/include/net/netns/sctp.h
>> @@ -129,6 +129,9 @@ struct netns_sctp {
>>
>> /* Threshold for autoclose timeout, in seconds. */
>> unsigned long max_autoclose;
>> +
>> + /* Flag to disable SCTP checksumming. */
>> + int checksum_disable;
>> };
>>
>> #endif /* __NETNS_SCTP_H__ */
>> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
>> index d9c93a7..06ebeaa 100644
>> --- a/include/net/sctp/structs.h
>> +++ b/include/net/sctp/structs.h
>> @@ -141,10 +141,6 @@ extern struct sctp_globals {
>> /* This is the sctp port control hash. */
>> int port_hashsize;
>> struct sctp_bind_hashbucket *port_hashtable;
>> -
>> - /* Flag to indicate whether computing and verifying checksum
>> - * is disabled. */
>> - bool checksum_disable;
>> } sctp_globals;
>>
>> #define sctp_max_instreams (sctp_globals.max_instreams)
>> @@ -156,7 +152,6 @@ extern struct sctp_globals {
>> #define sctp_assoc_hashtable (sctp_globals.assoc_hashtable)
>> #define sctp_port_hashsize (sctp_globals.port_hashsize)
>> #define sctp_port_hashtable (sctp_globals.port_hashtable)
>> -#define sctp_checksum_disable (sctp_globals.checksum_disable)
>>
>> /* SCTP Socket type: UDP or TCP style. */
>> typedef enum {
>> diff --git a/net/sctp/input.c b/net/sctp/input.c
>> index fa91aff..b9a25e1 100644
>> --- a/net/sctp/input.c
>> +++ b/net/sctp/input.c
>> @@ -140,8 +140,8 @@ int sctp_rcv(struct sk_buff *skb)
>> __skb_pull(skb, skb_transport_offset(skb));
>> if (skb->len < sizeof(struct sctphdr))
>> goto discard_it;
>> - if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
>> - sctp_rcv_checksum(net, skb) < 0)
>> + if (!net->sctp.checksum_disable && !skb_csum_unnecessary(skb) &&
>> + sctp_rcv_checksum(net, skb) < 0)
>> goto discard_it;
>>
>> skb_pull(skb, sizeof(struct sctphdr));
>> diff --git a/net/sctp/output.c b/net/sctp/output.c
>> index 5a55c55d..cdb5f49 100644
>> --- a/net/sctp/output.c
>> +++ b/net/sctp/output.c
>> @@ -395,6 +395,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
>> int padding; /* How much padding do we need? */
>> __u8 has_data = 0;
>> struct dst_entry *dst = tp->dst;
>> + struct net *net;
>> unsigned char *auth = NULL; /* pointer to auth in skb data */
>> __u32 cksum_buf_len = sizeof(struct sctphdr);
>>
>> @@ -541,7 +542,9 @@ int sctp_packet_transmit(struct sctp_packet *packet)
>> * Note: Adler-32 is no longer applicable, as has been replaced
>> * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
>> */
>> - if (!sctp_checksum_disable) {
>> + net = dev_net(dst->dev);
>> +
>> + if (!net->sctp.checksum_disable) {
>> if (!(dst->dev->features & NETIF_F_SCTP_CSUM)) {
>> __u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len);
>>
>> diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
>> index b52ec25..a570a63 100644
>> --- a/net/sctp/protocol.c
>> +++ b/net/sctp/protocol.c
>> @@ -1193,6 +1193,9 @@ static int __net_init sctp_net_init(struct net *net)
>> /* Whether Cookie Preservative is enabled(1) or not(0) */
>> net->sctp.cookie_preserve_enable = 1;
>>
>> + /* Whether SCTP checksumming is disabled(1) or not(0) */
>> + net->sctp.checksum_disable = 0;
>> +
>> /* Default sctp sockets to use md5 as their hmac alg */
>> #if defined (CONFIG_SCTP_DEFAULT_COOKIE_HMAC_MD5)
>> net->sctp.sctp_hmac_alg = "md5";
>> @@ -1549,6 +1552,4 @@ MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-132");
>> MODULE_ALIAS("net-pf-" __stringify(PF_INET6) "-proto-132");
>> MODULE_AUTHOR("Linux Kernel SCTP developers <linux-sctp@...r.kernel.org>");
>> MODULE_DESCRIPTION("Support for the SCTP protocol (RFC2960)");
>> -module_param_named(no_checksums, sctp_checksum_disable, bool, 0644);
>> -MODULE_PARM_DESC(no_checksums, "Disable checksums computing and verification");
>> MODULE_LICENSE("GPL");
>> diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
>> index 1906747..754809a 100644
>> --- a/net/sctp/sysctl.c
>> +++ b/net/sctp/sysctl.c
>> @@ -296,7 +296,15 @@ static struct ctl_table sctp_net_table[] = {
>> .extra1 = &max_autoclose_min,
>> .extra2 = &max_autoclose_max,
>> },
>> -
>> + {
>> + .procname = "checksum_disable",
>> + .data = &init_net.sctp.checksum_disable,
>> + .maxlen = sizeof(int),
>> + .mode = 0644,
>> + .proc_handler = proc_dointvec_minmax,
>> + .extra1 = &zero,
>> + .extra2 = &one,
>> + },
>> { /* sentinel */ }
>> };
>>
>>
>
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