linux-kernel - [PATCH v5 07/18] net: tls: Avoid assigning 'const' pointer to non-const pointer

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Message-Id: <20200511204150.27858-8-will@kernel.org>
Date:   Mon, 11 May 2020 21:41:39 +0100
From:   Will Deacon <will@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     elver@...gle.com, tglx@...utronix.de, paulmck@...nel.org,
        mingo@...nel.org, peterz@...radead.org, will@...nel.org
Subject: [PATCH v5 07/18] net: tls: Avoid assigning 'const' pointer to non-const pointer

tls_build_proto() uses WRITE_ONCE() to assign a 'const' pointer to a
'non-const' pointer. Cleanups to the implementation of WRITE_ONCE() mean
that this will give rise to a compiler warning, just like a plain old
assignment would do:

  | net/tls/tls_main.c: In function ‘tls_build_proto’:
  | ./include/linux/compiler.h:229:30: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  | net/tls/tls_main.c:640:4: note: in expansion of macro ‘smp_store_release’
  |   640 |    smp_store_release(&saved_tcpv6_prot, prot);
  |       |    ^~~~~~~~~~~~~~~~~

Drop the const qualifier from the local 'prot' variable, as it isn't
needed.

Cc: Boris Pismenny <borisp@...lanox.com>
Cc: Aviad Yehezkel <aviadye@...lanox.com>
Cc: John Fastabend <john.fastabend@...il.com>
Cc: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Will Deacon <will@...nel.org>
---
 net/tls/tls_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 156efce50dbd..b33e11c27cfa 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -629,7 +629,7 @@ struct tls_context *tls_ctx_create(struct sock *sk)
 static void tls_build_proto(struct sock *sk)
 {
 	int ip_ver = sk->sk_family == AF_INET6 ? TLSV6 : TLSV4;
-	const struct proto *prot = READ_ONCE(sk->sk_prot);
+	struct proto *prot = READ_ONCE(sk->sk_prot);
 
 	/* Build IPv6 TLS whenever the address of tcpv6 _prot changes */
 	if (ip_ver == TLSV6 &&
-- 
2.26.2.645.ge9eca65c58-goog