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

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Message-ID: <20250517000431.558180-1-stfomichev@gmail.com>
Date: Fri, 16 May 2025 17:04:31 -0700
From: Stanislav Fomichev <stfomichev@...il.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	horms@...nel.org,
	willemb@...gle.com,
	sagi@...mberg.me,
	stfomichev@...il.com,
	asml.silence@...il.com,
	almasrymina@...gle.com,
	kaiyuanz@...gle.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH net-next] net: devmem: remove min_t(iter_iov_len) in sendmsg

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). Remove iter_iov_len clamping. net_devmem_get_niov_at
already does PAGE_SIZE alignment and min_t(length) makes sure that
the last chunk (potentially smaller than PAGE_SIZE) is accounted
correctly.

Fixes: bd61848900bf ("net: devmem: Implement TX path")
Signed-off-by: Stanislav Fomichev <stfomichev@...il.com>
---
 net/core/datagram.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/core/datagram.c b/net/core/datagram.c
index e04908276a32..48fcfc1dcf47 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -712,7 +712,6 @@ zerocopy_fill_skb_from_devmem(struct sk_buff *skb, struct iov_iter *from,
 			return -EFAULT;
 
 		size = min_t(size_t, size, length);
-		size = min_t(size_t, size, iter_iov_len(from));
 
 		get_netmem(net_iov_to_netmem(niov));
 		skb_add_rx_frag_netmem(skb, i, net_iov_to_netmem(niov), off,
-- 
2.49.0