From mboxrd@z Thu Jan 1 00:00:00 1970 From: ddaney.cavm@gmail.com (David Daney) Date: Tue, 17 Nov 2015 16:04:53 -0800 Subject: [PATCH] arm64: Make smp_load_acquire() work with pointer to const argument. Message-ID: <1447805093-8716-1-git-send-email-ddaney.cavm@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: David Daney We are now getting this error when building: . . . CC init/do_mounts.o In file included from include/linux/tcp.h:22:0, from include/linux/ipv6.h:72, from include/net/ipv6.h:16, from include/linux/sunrpc/clnt.h:27, from include/linux/nfs_fs.h:30, from init/do_mounts.c:32: include/net/sock.h: In function ?sk_state_load?: include/net/sock.h:2238:2: error: read-only variable ?___p1? used as ?asm? output return smp_load_acquire(&sk->sk_state); ^ include/net/sock.h:2238:2: error: read-only variable ?___p1? used as ?asm? output include/net/sock.h:2238:2: error: read-only variable ?___p1? used as ?asm? output include/net/sock.h:2238:2: error: read-only variable ?___p1? used as ?asm? output . . . Fix the smp_load_acquire() implementation to discard the const qualifier in the type of the temporary variable with some tricky casting. Signed-off-by: David Daney --- arch/arm64/include/asm/barrier.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h index 624f967..52eb9b9 100644 --- a/arch/arm64/include/asm/barrier.h +++ b/arch/arm64/include/asm/barrier.h @@ -64,7 +64,8 @@ do { \ #define smp_load_acquire(p) \ ({ \ - typeof(*p) ___p1; \ + typeof((typeof(*p))(*p + 0)) ___p1; \ + compiletime_assert(sizeof(___p1) == sizeof(*p), "remove const"); \ compiletime_assert_atomic_type(*p); \ switch (sizeof(*p)) { \ case 1: \ -- 1.8.3.1