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Message-ID: <CA+55aFzY_LSLM8R2cbt=sZe8UeDtUZdX8zO6Bzf52EBg3H30qw@mail.gmail.com>
Date: Tue, 25 Nov 2014 09:28:33 -0800
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Paul McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Christian Borntraeger <borntraeger@...ibm.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Ingo Molnar <mingo@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Alexei Starovoitov <alexei.starovoitov@...il.com>,
David Howells <dhowells@...hat.com>,
Russell King <linux@....linux.org.uk>
Subject: Re: [PATCHv2 02/10] kernel: Provide READ_ONCE and ASSIGN_ONCE
On Tue, Nov 25, 2014 at 7:59 AM, Paul E. McKenney
<paulmck@...ux.vnet.ibm.com> wrote:
>
> We really need something like this to catch invalid sizes:
>
> default: invoke_nonexistent_function();
Actually, I wonder if we should make the default: case actually just
do something like
barrier();
memcpy(res, p, size);
barrier();
which in no way guarantees that it's an _atomic_ access, but it does
guarantee the semantics that you get one particular value and it won't
get reloaded later..
That would solve the crazy sparc pte issue too.
Linus
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