linux-kernel - Re: [PATCH v1] wifi: wext: propagate metadata on -E2BIG for GET ioctls

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Message-ID: <da586793e06d68e51af8f691e9aac82441d3808b.camel@sipsolutions.net>
Date: Mon, 25 Aug 2025 09:33:22 +0200
From: Johannes Berg <johannes@...solutions.net>
To: Callan Huang <luvings@...com>
Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] wifi: wext: propagate metadata on -E2BIG for GET
 ioctls

On Thu, 2025-08-07 at 21:10 +0800, Callan Huang wrote:
> When GET ioctls encounter insufficient buffer (-E2BIG),
> preserve u.data.length metadata in iwreq structure for size detection
> 
> Typical usage in userspace tools like 'iwlist wlan0 scanning':
> - Detect required buffer size via u.data.length
> - Implement retry logic with proper allocation

If you'd sent this patch 15 years ago I probably would've taken it, but
honestly, at this point ... no. Just use nl80211, or large buffers in
the userspace to start with. There's a very small buffer limit _anyway_,
so that getting the full scan list in busy environments is actually
impossible with wext.

johannes