Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: next build: 235 warnings 3 failures (next/next-20151117) | Date | Tue, 17 Nov 2015 20:17:17 +0100 |
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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?
Arnd
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