netdev - [PATCH net v2] tools: ynl-gen: fix nested array counting

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Message-ID: <20250902160001.760953-1-ast@fiberby.net>
Date: Tue,  2 Sep 2025 15:59:59 +0000
From: Asbjørn Sloth Tønnesen <ast@...erby.net>
To: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Cc: Asbjørn Sloth Tønnesen <ast@...erby.net>,
	Donald Hunter <donald.hunter@...il.com>,
	Simon Horman <horms@...nel.org>,
	Jacob Keller <jacob.e.keller@...el.com>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH net v2] tools: ynl-gen: fix nested array counting

The blamed commit introduced the concept of split attribute
counting, and later allocating an array to hold them, however
TypeArrayNest wasn't updated to use the new counting variable.

Abbreviated example from tools/net/ynl/generated/nl80211-user.c:
nl80211_if_combination_attributes_parse(...):
  unsigned int n_limits = 0;
  [...]
  ynl_attr_for_each(attr, nlh, yarg->ys->family->hdr_len)
	if (type == NL80211_IFACE_COMB_LIMITS)
		ynl_attr_for_each_nested(attr2, attr)
			dst->_count.limits++;
  if (n_limits) {
	dst->_count.limits = n_limits;
	/* allocate and parse attributes */
  }

In the above example n_limits is guaranteed to always be 0,
hence the conditional is unsatisfiable and is optimized out.

This patch changes the attribute counting to use n_limits++ in the
attribute counting loop in the above example.

Fixes: 58da455b31ba ("tools: ynl-gen: improve unwind on parsing errors")
Signed-off-by: Asbjørn Sloth Tønnesen <ast@...erby.net>
Reviewed-by: Jakub Kicinski <kuba@...nel.org>
---
v2:
  - Re-send as standalone patch.
  - Add Reviewed-By from Jakub, thanks!
v1: https://lore.kernel.org/netdev/20250901145034.525518-4-ast@fiberby.net/

 tools/net/ynl/pyynl/ynl_gen_c.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/net/ynl/pyynl/ynl_gen_c.py b/tools/net/ynl/pyynl/ynl_gen_c.py
index ef032e17fec44..eb295756c3bf7 100755
--- a/tools/net/ynl/pyynl/ynl_gen_c.py
+++ b/tools/net/ynl/pyynl/ynl_gen_c.py
@@ -830,7 +830,7 @@ class TypeArrayNest(Type):
                      'ynl_attr_for_each_nested(attr2, attr) {',
                      '\tif (ynl_attr_validate(yarg, attr2))',
                      '\t\treturn YNL_PARSE_CB_ERROR;',
-                     f'\t{var}->_count.{self.c_name}++;',
+                     f'\tn_{self.c_name}++;',
                      '}']
         return get_lines, None, local_vars
 
-- 
2.50.1