linux-kernel - Re: [PATCH net-next] net: devmem: remove min_t(iter_iov

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Message-ID: <20250517000907.GW2023217@ZenIV>
Date: Sat, 17 May 2025 01:09:07 +0100
From: Al Viro <viro@...iv.linux.org.uk>
To: Stanislav Fomichev <stfomichev@...il.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, horms@...nel.org,
	willemb@...gle.com, sagi@...mberg.me, asml.silence@...il.com,
	almasrymina@...gle.com, kaiyuanz@...gle.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] net: devmem: remove min_t(iter_iov_len) in
 sendmsg

On Fri, May 16, 2025 at 05:04:31PM -0700, Stanislav Fomichev wrote:
> iter_iov_len looks broken for UBUF. When iov_iter_advance is called
> for UBUF, it increments iov_offset and also decrements the count.
> This makes the iterator only go over half of the range (unless I'm
> missing something).

What do you mean by "broken"?  iov_iter_len(from) == "how much data is
left in that iterator".  That goes for all flavours, UBUF included...

Confused...