linux-kernel - Re: [PATCH 1/1] device-dax: avoid an unnecessary check in alloc_dev_dax

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Message-ID: <946f9111-f799-38a1-a185-d882668fa725@huawei.com>
Date:   Fri, 18 Dec 2020 14:02:02 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Dan Williams <dan.j.williams@...el.com>
CC:     Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Jane Chu <jane.chu@...cle.com>
Subject: Re: [PATCH 1/1] device-dax: avoid an unnecessary check in
 alloc_dev_dax_range()



On 2020/12/18 11:10, Dan Williams wrote:
> On Fri, Nov 20, 2020 at 1:23 AM Zhen Lei <thunder.leizhen@...wei.com> wrote:
>>
>> Swap the calling sequence of krealloc() and __request_region(), call the
>> latter first. In this way, the value of dev_dax->nr_range does not need to
>> be considered when __request_region() failed.
> 
> This looks ok, but I think I want to see another cleanup go in first
> before this to add a helper for trimming the last range off the set of
> ranges:
> 
> static void dev_dax_trim_range(struct dev_dax *dev_dax)
> {
>         int i = dev_dax->nr_range - 1;
>         struct range *range = &dev_dax->ranges[i].range;
>         struct dax_region *dax_region = dev_dax->region;
> 
>         dev_dbg(dev, "delete range[%d]: %#llx:%#llx\n", i,
>                 (unsigned long long)range->start,
>                 (unsigned long long)range->end);
> 
>         __release_region(&dax_region->res, range->start, range_len(range));
>         if (--dev_dax->nr_range == 0) {
>                 kfree(dev_dax->ranges);
>                 dev_dax->ranges = NULL;
>         }
> }
> 
> Care to do a lead in patch with that cleanup, then do this one?

I don't mind! You can add above helper first. After that, I'll update
and send this patch again.

> 
> I think that might also cleanup a memory leak report from Jane in
> addition to not needing the "goto" as well.
> 
> http://lore.kernel.org/r/c8a8a260-34c6-dbfc-1f19-25c23d01cb45@oracle.com
> 
> .
>