[PATCH 1/2] docs: net: sysctl documentation cleanup

From: Abdelrahman Fekry
Date: Thu Jun 12 2025 - 12:30:44 EST


I noticed that some boolean parameters have missing default values
(enabled/disabled) in the documentation so i checked the initialization
functions to get their default values, also there was some inconsistency
in the representation. During the process , i stumbled upon a typo in
cipso_rbm_struct_valid instead of cipso_rbm_struct_valid.

- Fixed typo in cipso_rbm_struct_valid
- Added missing default value declarations
- Standardized boolean representation (0/1 with enabled/disabled)

Signed-off-by: Abdelrahman Fekry <abdelrahmanfekry375@xxxxxxxxx>
---
Documentation/networking/ip-sysctl.rst | 37 +++++++++++++++++++++-----
1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 0f1251cce314..f7ff8c53f412 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -75,7 +75,7 @@ fwmark_reflect - BOOLEAN
If unset, these packets have a fwmark of zero. If set, they have the
fwmark of the packet they are replying to.

- Default: 0
+ Default: 0 (disabled)

fib_multipath_use_neigh - BOOLEAN
Use status of existing neighbor entry when determining nexthop for
@@ -368,7 +368,7 @@ tcp_autocorking - BOOLEAN
queue. Applications can still use TCP_CORK for optimal behavior
when they know how/when to uncork their sockets.

- Default : 1
+ Default : 1 (enabled)

tcp_available_congestion_control - STRING
Shows the available congestion control choices that are registered.
@@ -407,6 +407,12 @@ tcp_congestion_control - STRING

tcp_dsack - BOOLEAN
Allows TCP to send "duplicate" SACKs.
+ Possible values:
+ - 0 disabled
+ - 1 enabled
+
+ Default: 1 (enabled)

tcp_early_retrans - INTEGER
Tail loss probe (TLP) converts RTOs occurring due to tail
@@ -623,6 +629,8 @@ tcp_no_metrics_save - BOOLEAN
increases overall performance, but may sometimes cause performance
degradation. If set, TCP will not cache metrics on closing
connections.
+
+ Default: 0 (disabled)

tcp_no_ssthresh_metrics_save - BOOLEAN
Controls whether TCP saves ssthresh metrics in the route cache.
@@ -684,6 +692,8 @@ tcp_retrans_collapse - BOOLEAN
Bug-to-bug compatibility with some broken printers.
On retransmit try to send bigger packets to work around bugs in
certain TCP stacks.
+
+ Default: 1 (enabled)

tcp_retries1 - INTEGER
This value influences the time, after which TCP decides, that
@@ -739,6 +749,8 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max

tcp_sack - BOOLEAN
Enable select acknowledgments (SACKS).
+
+ Default: 1 (enabled)

tcp_comp_sack_delay_ns - LONG INTEGER
TCP tries to reduce number of SACK sent, using a timer
@@ -766,7 +778,7 @@ tcp_backlog_ack_defer - BOOLEAN
one ACK for the whole queue. This helps to avoid potential
long latencies at end of a TCP socket syscall.

- Default : true
+ Default : 1 (enabled)

tcp_slow_start_after_idle - BOOLEAN
If set, provide RFC2861 behavior and time out the congestion
@@ -781,7 +793,7 @@ tcp_stdurg - BOOLEAN
Most hosts use the older BSD interpretation, so if you turn this on
Linux might not communicate correctly with them.

- Default: FALSE
+ Default: 0 (disabled)

tcp_synack_retries - INTEGER
Number of times SYNACKs for a passive TCP connection attempt will
@@ -1018,6 +1030,10 @@ tcp_tw_reuse_delay - UNSIGNED INTEGER

tcp_window_scaling - BOOLEAN
Enable window scaling as defined in RFC1323.
+ - 0 - Disabled.
+ - 1 - Enabled.
+
+ Default: 1 (enabled)

tcp_shrink_window - BOOLEAN
This changes how the TCP receive window is calculated.
@@ -1160,7 +1176,7 @@ tcp_plb_enabled - BOOLEAN
congestion measure (e.g. ce_ratio). PLB needs a congestion measure to
make repathing decisions.

- Default: FALSE
+ Default: 0 (disabled)

tcp_plb_idle_rehash_rounds - INTEGER
Number of consecutive congested rounds (RTT) seen after which
@@ -1352,7 +1368,7 @@ cipso_rbm_optfmt - BOOLEAN

Default: 0

-cipso_rbm_structvalid - BOOLEAN
+cipso_rbm_strictvalid - BOOLEAN
If set, do a very strict check of the CIPSO option when
ip_options_compile() is called. If unset, relax the checks done during
ip_options_compile(). Either way is "safe" as errors are caught else
@@ -1933,10 +1949,15 @@ mcast_resolicit - INTEGER

disable_policy - BOOLEAN
Disable IPSEC policy (SPD) for this interface
+
+ Default: 0
+

disable_xfrm - BOOLEAN
Disable IPSEC encryption on this interface, whatever the policy

+ Default: 0
+
igmpv2_unsolicited_report_interval - INTEGER
The interval in milliseconds in which the next unsolicited
IGMPv1 or IGMPv2 report retransmit will take place.
@@ -1951,11 +1972,15 @@ igmpv3_unsolicited_report_interval - INTEGER

ignore_routes_with_linkdown - BOOLEAN
Ignore routes whose link is down when performing a FIB lookup.
+
+ Default: 0 (disabled)

promote_secondaries - BOOLEAN
When a primary IP address is removed from this interface
promote a corresponding secondary IP address instead of
removing all the corresponding secondary IP addresses.
+
+ Default: 0 (disabled)

drop_unicast_in_l2_multicast - BOOLEAN
Drop any unicast IP packets that are received in link-layer
--
2.25.1