[PATCH ethtool] netlink: require a value for hds-thresh and the TDR parameters

[PATCH ethtool] netlink: require a value for hds-thresh and the TDR parameters

[Dave Seddon]

hds-thresh (-G) and first, last, step and pair (--cable-test-tdr) take
a value, but their parser entries leave min_argc at 0. Given as the
last word on the line, the value handler reads the NULL that ends argv
and the error message prints it:

  # ethtool -G eth0 hds-thresh
  ethtool (-G): invalid value '(null)' for parameter 'hds-thresh'
  # ethtool --cable-test-tdr eth0 first 1 last
  ethtool (--cable-test-tdr): invalid value '(null)' for parameter 'last'

Set min_argc to 1, as every other value-taking parameter does, so the
parser reports the missing value itself:

  # ethtool -G eth0 hds-thresh
  ethtool (-G): no value for parameter 'hds-thresh'

Only the message changes: the exit status was already 1 and no request
was sent.

Fixes: 66e5dcf295c0 ("ethtool: Add support for configuring hds-thresh")
Fixes: 9561db9b76f4 ("Add cable test TDR support")
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Dave Seddon <dave.seddon.ca@gmail.com>
---
Checked by hand on a build of bae2dbd: all five parameters print the
"(null)" message before and "no value for parameter" after. make check
passes.

Claude found the issue while porting the code from C to Go, and drafted
the patch; I reviewed it and take responsibility for it.

 netlink/cable_test.c | 4 ++++
 netlink/rings.c      | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/netlink/cable_test.c b/netlink/cable_test.c
index fdb046e..648bf74 100644
--- a/netlink/cable_test.c
+++ b/netlink/cable_test.c
@@ -544,24 +544,28 @@ static const struct param_parser tdr_params[] = {
 		.type		= ETHTOOL_A_CABLE_TEST_TDR_CFG_FIRST,
 		.group		= ETHTOOL_A_CABLE_TEST_TDR_CFG,
 		.handler	= nl_parse_direct_m2cm,
+		.min_argc	= 1,
 	},
 	{
 		.arg		= "last",
 		.type		= ETHTOOL_A_CABLE_TEST_TDR_CFG_LAST,
 		.group		= ETHTOOL_A_CABLE_TEST_TDR_CFG,
 		.handler	= nl_parse_direct_m2cm,
+		.min_argc	= 1,
 	},
 	{
 		.arg		= "step",
 		.type		= ETHTOOL_A_CABLE_TEST_TDR_CFG_STEP,
 		.group		= ETHTOOL_A_CABLE_TEST_TDR_CFG,
 		.handler	= nl_parse_direct_m2cm,
+		.min_argc	= 1,
 	},
 	{
 		.arg		= "pair",
 		.type		= ETHTOOL_A_CABLE_TEST_TDR_CFG_PAIR,
 		.group		= ETHTOOL_A_CABLE_TEST_TDR_CFG,
 		.handler	= nl_parse_direct_u8,
+		.min_argc	= 1,
 	},
 	{}
 };
diff --git a/netlink/rings.c b/netlink/rings.c
index 5c695ab..22552df 100644
--- a/netlink/rings.c
+++ b/netlink/rings.c
@@ -202,7 +202,7 @@ static const struct param_parser sring_params[] = {
 		.arg		= "hds-thresh",
 		.type		= ETHTOOL_A_RINGS_HDS_THRESH,
 		.handler	= nl_parse_direct_u32,
-		.min_argc	= 0,
+		.min_argc	= 1,
 	},
 	{}
 };
-- 
2.56.0