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Re: next build: 235 warnings 3 failures (next/next-20151117)

From Will Deacon <will.deacon@arm.com>
Newsgroups linux.kernel
Subject Re: next build: 235 warnings 3 failures (next/next-20151117)
Date 2015-11-17 18:20 +0100
Message-ID <qvS5b-7Xf-15@gated-at.bofh.it> (permalink)
References <qvKhk-2Hb-21@gated-at.bofh.it> <qvKhk-2Hb-19@gated-at.bofh.it> <qvRC9-7wq-3@gated-at.bofh.it> <qvRVx-7TO-31@gated-at.bofh.it>
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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?

Will
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Thread

Re: next build: 235 warnings 3 failures (next/next-20151117) Arnd Bergmann <arnd@arndb.de> - 2015-11-17 10:00 +0100
  Re: next build: 235 warnings 3 failures (next/next-20151117) Will Deacon <will.deacon@arm.com> - 2015-11-17 17:50 +0100
    Re: next build: 235 warnings 3 failures (next/next-20151117) Eric Dumazet <eric.dumazet@gmail.com> - 2015-11-17 18:10 +0100
    Re: next build: 235 warnings 3 failures (next/next-20151117) Arnd Bergmann <arnd@arndb.de> - 2015-11-17 18:10 +0100
      Re: next build: 235 warnings 3 failures (next/next-20151117) Will Deacon <will.deacon@arm.com> - 2015-11-17 18:20 +0100
        Re: next build: 235 warnings 3 failures (next/next-20151117) Arnd Bergmann <arnd@arndb.de> - 2015-11-17 20:20 +0100
          Re: next build: 235 warnings 3 failures (next/next-20151117) Will Deacon <will.deacon@arm.com> - 2015-11-18 11:20 +0100
            RE: next build: 235 warnings 3 failures (next/next-20151117) David Laight <David.Laight@ACULAB.COM> - 2015-11-18 13:20 +0100
              Re: next build: 235 warnings 3 failures (next/next-20151117) Will Deacon <will.deacon@arm.com> - 2015-11-18 13:30 +0100
                RE: next build: 235 warnings 3 failures (next/next-20151117) David Laight <David.Laight@ACULAB.COM> - 2015-11-18 16:30 +0100
                Re: next build: 235 warnings 3 failures (next/next-20151117) Will Deacon <will.deacon@arm.com> - 2015-11-18 16:40 +0100
                RE: next build: 235 warnings 3 failures (next/next-20151117) David Laight <David.Laight@ACULAB.COM> - 2015-11-18 17:00 +0100
          RE: next build: 235 warnings 3 failures (next/next-20151117) David Laight <David.Laight@ACULAB.COM> - 2015-11-18 11:30 +0100

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