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From: david.laight.linux@gmail.com
To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	David Laight <david.laight.linux@gmail.com>
Subject: [PATCH 40/44] net: Don't pass bitfields to max_t()
Date: Wed, 19 Nov 2025 22:41:36 +0000	[thread overview]
Message-ID: <20251119224140.8616-41-david.laight.linux@gmail.com> (raw)
In-Reply-To: <20251119224140.8616-1-david.laight.linux@gmail.com>

From: David Laight <david.laight.linux@gmail.com>

It is invalid to use sizeof() or typeof() in bitfields which stops
them being passed to max().
This has been fixed by using max_t().
I want to add some checks to max_t() to detect cases where the cast
discards non-zero high bits - which uses sizeof().
So add 0 to the bitfield (converting it to int) then use max().

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
 include/net/tcp_ecn.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/net/tcp_ecn.h b/include/net/tcp_ecn.h
index f13e5cd2b1ac..14c00404a95f 100644
--- a/include/net/tcp_ecn.h
+++ b/include/net/tcp_ecn.h
@@ -196,7 +196,7 @@ static inline void tcp_accecn_opt_demand_min(struct sock *sk,
 	struct tcp_sock *tp = tcp_sk(sk);
 	u8 opt_demand;
 
-	opt_demand = max_t(u8, opt_demand_min, tp->accecn_opt_demand);
+	opt_demand = max(opt_demand_min, tp->accecn_opt_demand + 0);
 	tp->accecn_opt_demand = opt_demand;
 }
 
@@ -303,8 +303,7 @@ static inline void tcp_ecn_received_counters(struct sock *sk,
 			u32 bytes_mask = GENMASK_U32(31, 22);
 
 			tp->received_ecn_bytes[ecnfield - 1] += len;
-			tp->accecn_minlen = max_t(u8, tp->accecn_minlen,
-						  minlen);
+			tp->accecn_minlen = max(tp->accecn_minlen + 0, minlen);
 
 			/* Send AccECN option at least once per 2^22-byte
 			 * increase in any ECN byte counter.
-- 
2.39.5


  parent reply	other threads:[~2025-11-19 22:42 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-19 22:40 [PATCH 00/44] Change a lot of min_t() that might mask high bits david.laight.linux
2025-11-19 22:41 ` [PATCH 07/44] net/core/flow_dissector: Fix cap of __skb_flow_dissect() return value david.laight.linux
2025-11-19 22:41 ` [PATCH 08/44] net: ethtool: Use min3() instead of nested min_t(u16,...) david.laight.linux
2025-11-19 22:41 ` [PATCH 09/44] ipv6: __ip6_append_data() don't abuse max_t() casts david.laight.linux
2025-11-20  0:32   ` bot+bpf-ci
2025-11-20 11:16     ` David Laight
2025-11-20 13:50       ` Chris Mason
2025-11-19 22:41 ` [PATCH 21/44] drivers/net/ethernet/realtek: use min() instead of min_t() david.laight.linux
2025-11-19 22:41 ` david.laight.linux [this message]
2025-11-19 22:41 ` [PATCH 41/44] net/core: Change loop conditions so min() can be used david.laight.linux
2025-11-19 22:41 ` [PATCH 42/44] net: use min() instead of min_t() david.laight.linux
2025-11-19 22:41 ` [PATCH 43/44] net/netlink: Use umin() to avoid min_t(int, ...) discarding high bits david.laight.linux
2025-11-19 22:41 ` [PATCH 44/44] net/mptcp: Change some dubious min_t(int, ...) to min() david.laight.linux
2025-12-18 17:33   ` Matthieu Baerts
2025-12-18 20:15     ` David Laight
2025-12-19 10:48       ` Matthieu Baerts
2025-11-20  1:47 ` [PATCH 00/44] Change a lot of min_t() that might mask high bits Jakub Kicinski
2025-11-20  9:38 ` Lorenzo Stoakes
2025-11-20 14:52 ` (subset) " Jens Axboe
2025-11-24  9:49 ` Herbert Xu

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