From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 05/18] Add io_uring IO interface
Date: Mon, 28 Jan 2019 12:32:09 -0700
Message-ID: <7a076774-f099-521c-8bf5-dc8c7c763bc4@kernel.dk>
References: <20190123153536.7081-1-axboe@kernel.dk>
 <20190123153536.7081-6-axboe@kernel.dk> <20190128145700.GA9795@lst.de>
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 <20190128163436.GA12427@lst.de>
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To: Christoph Hellwig <hch@lst.de>
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On 1/28/19 9:34 AM, Christoph Hellwig wrote:
> On Mon, Jan 28, 2019 at 09:26:42AM -0700, Jens Axboe wrote:
>>>> +static void io_free_scq_urings(struct io_ring_ctx *ctx)
>>>> +{
>>>> +	if (ctx->sq_ring) {
>>>> +		page_frag_free(ctx->sq_ring);
>>>> +		ctx->sq_ring = NULL;
>>>> +	}
>>>> +	if (ctx->sq_sqes) {
>>>> +		page_frag_free(ctx->sq_sqes);
>>>> +		ctx->sq_sqes = NULL;
>>>> +	}
>>>> +	if (ctx->cq_ring) {
>>>> +		page_frag_free(ctx->cq_ring);
>>>> +		ctx->cq_ring = NULL;
>>>> +	}
>>>
>>> Why is this using the page_frag helpers?  Also the callers just free
>>> these ctx structure, so there isn't much of a point zeroing them out.
>>
>> Why not use the page frag helpers? No point in open-coding it. I can
>> kill the zeroing, double call would be a bug anyway.
> 
> Because they are at a different level of abstraction, and someone
> might change the implementation, and is unlikely to catch the io_uring
> mix of interfaces.  If you think this is really useful we should also
> export the helpers under a different name and with documentation.
> (and add a __get_free_pages version that returns a pointer..)

Fair enough, I'll avoid using the page_frag_free().

-- 
Jens Axboe

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