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Date: Fri, 7 Aug 2015 16:57:37 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Vineet Gupta <vgupta@synopsys.com>
Cc: Oleg Nesterov <oleg@redhat.com>, Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] coredump: Replace opencoded set_mask_bits()
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On Fri, Aug 07, 2015 at 08:14:03PM +0530, Vineet Gupta wrote:

> See, I have such a cmpxchg loop in ARC code - originally from Peter :-)
> arch/arc/kernel/smp.c. @ipi_data_ptr is NOT atomic_t
> 
> 	do {
> 		new = old = ACCESS_ONCE(*ipi_data_ptr);
> 		new |= 1U << msg;
> 	} while (cmpxchg(ipi_data_ptr, old, new) != old);
> 

Well, you'll have atomic_or() real soon now.