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From: Christoph Hellwig <hch@lst.de>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Philip Yang <Philip.Yang@amd.com>,
	Ralph Campbell <rcampbell@nvidia.com>,
	John Hubbard <jhubbard@nvidia.com>,
	Felix.Kuehling@amd.com, dri-devel@lists.freedesktop.org,
	linux-mm@kvack.org, Jerome Glisse <jglisse@redhat.com>,
	Jason Gunthorpe <jgg@mellanox.com>,
	amd-gfx@lists.freedesktop.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v2 hmm 4/9] mm/hmm: remove HMM_FAULT_SNAPSHOT
Date: Tue, 24 Mar 2020 08:33:39 +0100	[thread overview]
Message-ID: <20200324073339.GC23447@lst.de> (raw)
In-Reply-To: <20200324011457.2817-5-jgg@ziepe.ca>

>  
> +/*
> + * If the valid flag is masked off, and default_flags doesn't set valid, then
> + * hmm_pte_need_fault() always returns 0.
> + */
> +static bool hmm_can_fault(struct hmm_range *range)
> +{
> +	return ((range->flags[HMM_PFN_VALID] & range->pfn_flags_mask) |
> +		range->default_flags) &
> +	       range->flags[HMM_PFN_VALID];
> +}

So my idea behind the helper was to turn this into something readable :)

E.g.

/*
 * We only need to fault if either the default mask requires to fault all
 * pages, or at least the mask allows for individual pages to be faulted.
 */
static bool hmm_can_fault(struct hmm_range *range)
{
	return ((range->default_flags | range->pfn_flags_mask) &
		range->flags[HMM_PFN_VALID]);
}

In fact now that I managed to destill it down to this I'm not even
sure we really even need the helper, although the comment really helps.
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WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>,
	Ralph Campbell <rcampbell@nvidia.com>,
	Felix.Kuehling@amd.com, linux-mm@kvack.org,
	John Hubbard <jhubbard@nvidia.com>,
	dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
	Christoph Hellwig <hch@lst.de>, Philip Yang <Philip.Yang@amd.com>,
	Jason Gunthorpe <jgg@mellanox.com>
Subject: Re: [PATCH v2 hmm 4/9] mm/hmm: remove HMM_FAULT_SNAPSHOT
Date: Tue, 24 Mar 2020 08:33:39 +0100	[thread overview]
Message-ID: <20200324073339.GC23447@lst.de> (raw)
In-Reply-To: <20200324011457.2817-5-jgg@ziepe.ca>

>  
> +/*
> + * If the valid flag is masked off, and default_flags doesn't set valid, then
> + * hmm_pte_need_fault() always returns 0.
> + */
> +static bool hmm_can_fault(struct hmm_range *range)
> +{
> +	return ((range->flags[HMM_PFN_VALID] & range->pfn_flags_mask) |
> +		range->default_flags) &
> +	       range->flags[HMM_PFN_VALID];
> +}

So my idea behind the helper was to turn this into something readable :)

E.g.

/*
 * We only need to fault if either the default mask requires to fault all
 * pages, or at least the mask allows for individual pages to be faulted.
 */
static bool hmm_can_fault(struct hmm_range *range)
{
	return ((range->default_flags | range->pfn_flags_mask) &
		range->flags[HMM_PFN_VALID]);
}

In fact now that I managed to destill it down to this I'm not even
sure we really even need the helper, although the comment really helps.


  reply	other threads:[~2020-03-24  8:14 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24  1:14 [PATCH v2 hmm 0/9] Small hmm_range_fault() cleanups Jason Gunthorpe
2020-03-24  1:14 ` Jason Gunthorpe
2020-03-24  1:14 ` Jason Gunthorpe
2020-03-24  1:14 ` [PATCH v2 hmm 1/9] mm/hmm: remove pgmap checking for devmap pages Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  1:14 ` [PATCH v2 hmm 2/9] mm/hmm: return the fault type from hmm_pte_need_fault() Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  7:27   ` Christoph Hellwig
2020-03-24  7:27     ` Christoph Hellwig
2020-03-24 18:58     ` Jason Gunthorpe
2020-03-24 18:58       ` Jason Gunthorpe
2020-03-24 18:58       ` Jason Gunthorpe
2020-03-24  1:14 ` [PATCH v2 hmm 3/9] mm/hmm: remove unused code and tidy comments Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  7:27   ` Christoph Hellwig
2020-03-24  7:27     ` Christoph Hellwig
2020-03-24  1:14 ` [PATCH v2 hmm 4/9] mm/hmm: remove HMM_FAULT_SNAPSHOT Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  7:33   ` Christoph Hellwig [this message]
2020-03-24  7:33     ` Christoph Hellwig
2020-03-24 19:31     ` Jason Gunthorpe
2020-03-24 19:31       ` Jason Gunthorpe
2020-03-24 19:31       ` Jason Gunthorpe
2020-03-24  1:14 ` [PATCH v2 hmm 5/9] mm/hmm: remove the CONFIG_TRANSPARENT_HUGEPAGE #ifdef Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  7:33   ` Christoph Hellwig
2020-03-24  7:33     ` Christoph Hellwig
2020-03-24  1:14 ` [PATCH v2 hmm 6/9] mm/hmm: use device_private_entry_to_pfn() Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  7:34   ` Christoph Hellwig
2020-03-24  7:34     ` Christoph Hellwig
2020-03-24  1:14 ` [PATCH v2 hmm 7/9] mm/hmm: do not unconditionally set pfns when returning EBUSY Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  7:37   ` Christoph Hellwig
2020-03-24  7:37     ` Christoph Hellwig
2020-03-24 15:47     ` Jason Gunthorpe
2020-03-24 15:47       ` Jason Gunthorpe
2020-03-24 15:47       ` Jason Gunthorpe
2020-03-24  1:14 ` [PATCH v2 hmm 8/9] mm/hmm: do not set pfns when returning an error code Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  7:38   ` Christoph Hellwig
2020-03-24  7:38     ` Christoph Hellwig
2020-03-24  1:14 ` [PATCH v2 hmm 9/9] mm/hmm: return error for non-vma snapshots Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  1:14   ` Jason Gunthorpe
2020-03-24  7:45   ` Christoph Hellwig
2020-03-24  7:45     ` Christoph Hellwig
2020-03-26 21:21 ` [PATCH v2 hmm 0/9] Small hmm_range_fault() cleanups Ralph Campbell
2020-03-26 21:21   ` Ralph Campbell
2020-03-26 21:21   ` Ralph Campbell
  -- strict thread matches above, loose matches on Subject: below --
2020-03-27 20:00 [PATCH v3 " Jason Gunthorpe
2020-03-27 20:00 ` [PATCH v2 hmm 4/9] mm/hmm: remove HMM_FAULT_SNAPSHOT Jason Gunthorpe
2020-03-27 20:00   ` Jason Gunthorpe
2020-03-27 20:00   ` Jason Gunthorpe
2020-03-28  8:11   ` Christoph Hellwig
2020-03-28  8:11     ` Christoph Hellwig

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