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Date: Mon, 15 Dec 2008 12:15:44 -0200
From: Arnaldo Carvalho de Melo <acme@...hat.com>
To: Gerrit Renker <gerrit@....abdn.ac.uk>
Cc: davem@...emloft.net, dccp@...r.kernel.org, netdev@...r.kernel.org,
Kernel Janitors <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH 4/5] dccp: Initialisation and type-checking of feature
sysctls
Em Sat, Dec 13, 2008 at 02:41:24PM +0100, Gerrit Renker escreveu:
> This patch takes care of initialising and type-checking sysctls related to
> feature negotiation. Type checking is important since some of the sysctls
> now directly act on the feature-negotiation process.
>
> The sysctls are initialised with the known default values for each feature.
> For the type-checking the value constraints from RFC 4340 are used:
>
> * Sequence Window uses the specified Wmin=32, the maximum is ulong (4 bytes),
> tested and confirmed that it works up to 4294967295 - for Gbps speed;
> * Ack Ratio is between 0 .. 0xffff (2-byte unsigned integer);
> * CCIDs are between 0 .. 255;
> * request_retries, retries1, retries2 also between 0..255 for good measure;
> * tx_qlen is checked to be non-negative;
> * sync_ratelimit remains as before.
>
> Further changes:
> ----------------
> Performed s@...ctl_dccp_feat@...ctl_dccp@g since the sysctls are now in feat.c.
>
> Signed-off-by: Gerrit Renker <gerrit@....abdn.ac.uk>
> Acked-by: Ian McDonald <ian.mcdonald@...di.co.nz>
> ---
> include/linux/dccp.h | 8 --------
> net/dccp/dccp.h | 3 ---
> net/dccp/feat.c | 11 ++++++++---
> net/dccp/feat.h | 8 ++++++++
> net/dccp/options.c | 4 ----
> net/dccp/sysctl.c | 43 ++++++++++++++++++++++++++++++-------------
> 6 files changed, 46 insertions(+), 31 deletions(-)
>
> --- a/net/dccp/feat.h
> +++ b/net/dccp/feat.h
> @@ -100,6 +100,13 @@ struct ccid_dependency {
> u8 val;
> };
>
> +/*
> + * Sysctls to seed defaults for feature negotiation
> + */
> +extern unsigned long sysctl_dccp_sequence_window;
> +extern int sysctl_dccp_rx_ccid;
> +extern int sysctl_dccp_tx_ccid;
> +
> #ifdef CONFIG_IP_DCCP_DEBUG
> extern const char *dccp_feat_typename(const u8 type);
> extern const char *dccp_feat_name(const u8 feat);
> @@ -114,6 +121,7 @@ static inline void dccp_feat_debug(const u8 type, const u8 feat, const u8 val)
> #endif /* CONFIG_IP_DCCP_DEBUG */
>
> extern int dccp_feat_init(struct sock *sk);
> +extern void dccp_feat_initialise_sysctls(void);
> extern int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
> u8 const *list, u8 len);
> extern int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val);
> --- a/net/dccp/feat.c
> +++ b/net/dccp/feat.c
> @@ -25,6 +25,11 @@
> #include "ccid.h"
> #include "feat.h"
>
> +/* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */
> +unsigned long sysctl_dccp_sequence_window __read_mostly = 100;
> +int sysctl_dccp_rx_ccid __read_mostly = 2,
> + sysctl_dccp_tx_ccid __read_mostly = 2;
> +
> /*
> * Feature activation handlers.
> *
> @@ -1146,7 +1151,7 @@ int dccp_feat_init(struct sock *sk)
>
> /* Non-negotiable (NN) features */
> rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0,
> - sysctl_dccp_feat_sequence_window);
> + sysctl_dccp_sequence_window);
> if (rc)
> return rc;
>
> @@ -1177,8 +1182,8 @@ int dccp_feat_init(struct sock *sk)
> if (ccid_request_modules(tx.val, tx.len))
> goto free_ccid_lists;
>
> - if (!dccp_feat_prefer(sysctl_dccp_feat_tx_ccid, tx.val, tx.len) ||
> - !dccp_feat_prefer(sysctl_dccp_feat_rx_ccid, rx.val, rx.len))
> + if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) ||
> + !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len))
> goto free_ccid_lists;
>
> rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len);
> --- a/net/dccp/dccp.h
> +++ b/net/dccp/dccp.h
> @@ -95,9 +95,6 @@ extern void dccp_time_wait(struct sock *sk, int state, int timeo);
> extern int sysctl_dccp_request_retries;
> extern int sysctl_dccp_retries1;
> extern int sysctl_dccp_retries2;
> -extern int sysctl_dccp_feat_sequence_window;
> -extern int sysctl_dccp_feat_rx_ccid;
> -extern int sysctl_dccp_feat_tx_ccid;
> extern int sysctl_dccp_tx_qlen;
> extern int sysctl_dccp_sync_ratelimit;
>
> --- a/include/linux/dccp.h
> +++ b/include/linux/dccp.h
> @@ -355,14 +355,6 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
> return __dccp_hdr_len(dccp_hdr(skb));
> }
>
> -
> -/* initial values for each feature */
> -#define DCCPF_INITIAL_SEQUENCE_WINDOW 100
> -#define DCCPF_INITIAL_ACK_RATIO 2
> -#define DCCPF_INITIAL_CCID DCCPC_CCID2
> -/* FIXME: for now we're default to 1 but it should really be 0 */
> -#define DCCPF_INITIAL_SEND_NDP_COUNT 1
> -
> /**
> * struct dccp_request_sock - represent DCCP-specific connection request
> * @dreq_inet_rsk: structure inherited from
> --- a/net/dccp/options.c
> +++ b/net/dccp/options.c
> @@ -23,10 +23,6 @@
> #include "dccp.h"
> #include "feat.h"
>
> -int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
> -int sysctl_dccp_feat_rx_ccid = DCCPF_INITIAL_CCID;
> -int sysctl_dccp_feat_tx_ccid = DCCPF_INITIAL_CCID;
> -
> u64 dccp_decode_value_var(const u8 *bf, const u8 len)
> {
> u64 value = 0;
> --- a/net/dccp/sysctl.c
> +++ b/net/dccp/sysctl.c
> @@ -18,55 +18,72 @@
> #error This file should not be compiled without CONFIG_SYSCTL defined
> #endif
>
> +/* Boundary values */
> +static int zero = 0,
> + u8_max = 0xFF;
I wonder if these aren't available for wider use... some files have it:
./kernel/sysctl.c
./fs/inotify_user.c
./net/sunrpc/xprtrdma/transport.c
./net/ipv4/ip_fragment.c
./net/ipv4/sysctl_net_ipv4.c
./net/sctp/sysctl.c (well, this one also does the not needed '= 0' :) */
static int zero;
Some others, such as ./net/netrom/sysctl_net_netrom.c, could also use it
And one, etc, and it seems some people are even more crazy about saving
some bytes:
/* Constants used for minimum and maximum */
#if defined(CONFIG_HIGHMEM) || defined(CONFIG_DETECT_SOFTLOCKUP)
static int one = 1;
#endif
Unsure if the cost of exporting this to modules will do us good tho...
Perhaps some janitor may be interested in doing some measurements and
looking at u8_max (int_max, etc) too? :-)
Other than that:
Acked-by: Arnaldo Carvalho de Melo <acme@...hat.com>
- Arnaldo
> +static unsigned long seqw_min = 32;
> +
> static struct ctl_table dccp_default_table[] = {
> {
> .procname = "seq_window",
> - .data = &sysctl_dccp_feat_sequence_window,
> - .maxlen = sizeof(sysctl_dccp_feat_sequence_window),
> + .data = &sysctl_dccp_sequence_window,
> + .maxlen = sizeof(sysctl_dccp_sequence_window),
> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_doulongvec_minmax,
> + .extra1 = &seqw_min, /* RFC 4340, 7.5.2 */
> },
> {
> .procname = "rx_ccid",
> - .data = &sysctl_dccp_feat_rx_ccid,
> - .maxlen = sizeof(sysctl_dccp_feat_rx_ccid),
> + .data = &sysctl_dccp_rx_ccid,
> + .maxlen = sizeof(sysctl_dccp_rx_ccid),
> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_dointvec_minmax,
> + .extra1 = &zero,
> + .extra2 = &u8_max, /* RFC 4340, 10. */
> },
> {
> .procname = "tx_ccid",
> - .data = &sysctl_dccp_feat_tx_ccid,
> - .maxlen = sizeof(sysctl_dccp_feat_tx_ccid),
> + .data = &sysctl_dccp_tx_ccid,
> + .maxlen = sizeof(sysctl_dccp_tx_ccid),
> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_dointvec_minmax,
> + .extra1 = &zero,
> + .extra2 = &u8_max, /* RFC 4340, 10. */
> },
> {
> .procname = "request_retries",
> .data = &sysctl_dccp_request_retries,
> .maxlen = sizeof(sysctl_dccp_request_retries),
> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_dointvec_minmax,
> + .extra1 = &zero,
> + .extra2 = &u8_max,
> },
> {
> .procname = "retries1",
> .data = &sysctl_dccp_retries1,
> .maxlen = sizeof(sysctl_dccp_retries1),
> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_dointvec_minmax,
> + .extra1 = &zero,
> + .extra2 = &u8_max,
> },
> {
> .procname = "retries2",
> .data = &sysctl_dccp_retries2,
> .maxlen = sizeof(sysctl_dccp_retries2),
> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_dointvec_minmax,
> + .extra1 = &zero,
> + .extra2 = &u8_max,
> },
> {
> .procname = "tx_qlen",
> .data = &sysctl_dccp_tx_qlen,
> .maxlen = sizeof(sysctl_dccp_tx_qlen),
> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_dointvec_minmax,
> + .extra1 = &zero,
> },
> {
> .procname = "sync_ratelimit",
> --
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