linux-kernel - Re: [PATCH v2 1/3] mm/mmu_notifier: use structure for invalidate_range

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Date:   Wed, 5 Dec 2018 17:35:20 +0100
From:   Jan Kara <jack@...e.cz>
To:     jglisse@...hat.com
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Ross Zwisler <zwisler@...nel.org>, Jan Kara <jack@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Michal Hocko <mhocko@...nel.org>,
        Christian Koenig <christian.koenig@....com>,
        Felix Kuehling <felix.kuehling@....com>,
        Ralph Campbell <rcampbell@...dia.com>,
        John Hubbard <jhubbard@...dia.com>, kvm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-rdma@...r.kernel.org,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] mm/mmu_notifier: use structure for
 invalidate_range_start/end callback

On Wed 05-12-18 00:36:26, jglisse@...hat.com wrote:
> diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
> index 5119ff846769..5f6665ae3ee2 100644
> --- a/mm/mmu_notifier.c
> +++ b/mm/mmu_notifier.c
> @@ -178,14 +178,20 @@ int __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
>  				  unsigned long start, unsigned long end,
>  				  bool blockable)
>  {
> +	struct mmu_notifier_range _range, *range = &_range;

Why these games with two variables?

>  	struct mmu_notifier *mn;
>  	int ret = 0;
>  	int id;
>  
> +	range->blockable = blockable;
> +	range->start = start;
> +	range->end = end;
> +	range->mm = mm;
> +

Use your init function for this?

>  	id = srcu_read_lock(&srcu);
>  	hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
>  		if (mn->ops->invalidate_range_start) {
> -			int _ret = mn->ops->invalidate_range_start(mn, mm, start, end, blockable);
> +			int _ret = mn->ops->invalidate_range_start(mn, range);
>  			if (_ret) {
>  				pr_info("%pS callback failed with %d in %sblockable context.\n",
>  						mn->ops->invalidate_range_start, _ret,
> @@ -205,9 +211,20 @@ void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
>  					 unsigned long end,
>  					 bool only_end)
>  {
> +	struct mmu_notifier_range _range, *range = &_range;
>  	struct mmu_notifier *mn;
>  	int id;
>  
> +	/*
> +	 * The end call back will never be call if the start refused to go
> +	 * through because of blockable was false so here assume that we
> +	 * can block.
> +	 */
> +	range->blockable = true;
> +	range->start = start;
> +	range->end = end;
> +	range->mm = mm;
> +

The same as above.

Otherwise the patch looks good to me.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR