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From: David Howells <dhowells@redhat.com>
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To: Peter Zijlstra <peterz@infradead.org>
Cc: dhowells@redhat.com, Dan Williams <dan.j.williams@intel.com>,
        linux-nvdimm <linux-nvdimm@lists.01.org>,
        Ingo Molnar <mingo@redhat.com>, Christoph Hellwig <hch@lst.de>,
        david <david@fromorbit.com>, linux-xfs <linux-xfs@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>, Jan Kara <jack@suse.cz>,
        Ross Zwisler <ross.zwisler@linux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [RFC][PATCH] sched/wait_bit: Introduce wait_var_event()/wake_up_var()
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Date: Thu, 15 Mar 2018 14:45:20 +0000
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Peter Zijlstra <peterz@infradead.org> wrote:

> Does the below address things sufficiently clear?

Yep.

> +wait_queue_head_t *__var_waitqueue(void *p)
> +{
> +	if (BITS_PER_LONG == 64) {
> +		unsigned long q = (unsigned long)p;
> +
> +		return bit_waitqueue((void *)(q & ~1), q & 1);
> +	}
> +	return bit_waitqueue(p, 0);
> +}

You might be better off not using bit_waitqueue() but rather do the
calculation directly since you don't actually have a bit number.

David