dccp: Initialisation and type-checking of feature sysctls
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 impact 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.
Notes:
------
1. Die s@sysctl_dccp_feat@sysctl_dccp@g since the sysctls are now in feat.c.
2. As pointed out by Arnaldo, the pattern of type-checking repeats itself in
other places, sometimes with exactly the same kind of definitions (e.g.
"static int zero;"). It may be a good idea (kernel janitors?) to consolidate
type checking. For the sake of keeping the changeset small and in order not
to affect other subsystems, I have not strived to generalise here.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/feat.c b/net/dccp/feat.c
index 7303f79..12006e9 100644
--- 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 @@
/* 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;
@@ -1172,8 +1177,8 @@
ccid_get_builtin_ccids(&rx.val, &rx.len))
return -ENOBUFS;
- 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);