From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: next build: 235 warnings 3 failures (next/next-20151117) Date: Wed, 18 Nov 2015 10:14:28 +0000 Message-ID: <20151118101427.GC22731@arm.com> References: <564a9961.878b420a.331b8.fffffd62@mx.google.com> <6370082.rfihnaNWhf@wuerfel> <20151117171236.GJ30101@arm.com> <3723928.99NZh1TC6E@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Catalin Marinas , kernel-build-reports@lists.linaro.org, olof@lixom.net, David Miller , eric.dumazet@gmail.com, netdev@vger.kernel.org, linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org To: Arnd Bergmann Return-path: Content-Disposition: inline In-Reply-To: <3723928.99NZh1TC6E@wuerfel> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, Nov 17, 2015 at 08:17:17PM +0100, Arnd Bergmann wrote: > On Tuesday 17 November 2015 17:12:37 Will Deacon wrote: > > On Tue, Nov 17, 2015 at 06:03:40PM +0100, Arnd Bergmann wrote: > > > On Tuesday 17 November 2015 16:44:53 Will Deacon wrote: > > > > > 8<---- > > > > > Subject: ARM64: make smp_load_acquire() work with const arguments > > > > > > > > > > smp_load_acquire() uses typeof() to declare a local variable for temporarily > > > > > storing the output of the memory access. This fails when the argument is > > > > > constant, because the assembler complains about using a constant register > > > > > as output: > > > > > > > > > > arch/arm64/include/asm/barrier.h:71:3: error: read-only variable '___p1' > > > > > used as 'asm' output > > > > > > > > Do you know the usage in the kernel causing this warning? > > > > > > A newly introduced function in include/net/sock.h: > > > > > > static inline int sk_state_load(const struct sock *sk) > > > { > > > return smp_load_acquire(&sk->sk_state); > > > } > > > > Hmm, maybe we could play a similar trick to READ_ONCE by declaring an > > anonymous union and writing through the non-const member? > > Yes, I think that would work, if you think we need to care about the > case where we read into a structure. > > Can you come up with a patch for that? Done: http://lists.infradead.org/pipermail/linux-arm-kernel/2015-November/386094.html Will