netdev - Re: [PATCH net 3/4] tools: ynl-gen: fix nested array counting

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Message-ID: <20250901115650.107e078e@kernel.org>
Date: Mon, 1 Sep 2025 11:56:50 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Asbjørn Sloth Tønnesen
 <ast@...erby.net>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Donald Hunter
 <donald.hunter@...il.com>, Simon Horman <horms@...nel.org>, Jacob Keller
 <jacob.e.keller@...el.com>, Stanislav Fomichev <sdf@...ichev.me>, "Matthieu
 Baerts (NGI0)" <matttbe@...nel.org>, David Ahern <dsahern@...nel.org>,
 Chuck Lever <chuck.lever@...cle.com>, wireguard@...ts.zx2c4.com,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 3/4] tools: ynl-gen: fix nested array counting

On Mon,  1 Sep 2025 14:50:22 +0000 Asbjørn Sloth Tønnesen wrote:
> 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.

Looks good, thanks!

Reviewed-by: Jakub Kicinski <kuba@...nel.org>