linux-kernel - Re: [Xen-devel] [PATCH v6 1/1] xen/time: do not decrease steal time after live migration on xen

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Date:   Fri, 3 Nov 2017 07:50:31 +0800
From:   Dongli Zhang <dongli.zhang@...cle.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Cc:     jgross@...e.com, joao.m.martins@...cle.com
Subject: Re: [Xen-devel] [PATCH v6 1/1] xen/time: do not decrease steal time
 after live migration on xen

Hi Boris,

On 11/03/2017 04:28 AM, Boris Ostrovsky wrote:
> On 11/01/2017 09:19 PM, Dongli Zhang wrote:
>> Hi Boris,
>>
>> I have received from lkp@...el.com that the prior version of patch hit issue
>> during compilation with aarch64-linux-gnu-gcc. I think this patch reviewed by
>> you would hit the same compiling issue on arm64 (there is no issue with x86_64).
>>
>> -------------------------------------------------------------
>>
>> 1st issue:
>>
>> Without including header <linux/slab.h> into driver/xen/time.c, compilation on
>> x86_64 works well (without any warning or error) but arm64 would hit the
>> following error:
>>
>> drivers/xen/time.c: In function ‘xen_manage_runstate_time’:
>> drivers/xen/time.c:94:20: error: implicit declaration of function
>> ‘kmalloc_array’ [-Werror=implicit-function-declaration]
>>    runstate_delta = kmalloc_array(num_possible_cpus(),
>>                     ^
>>
>> drivers/xen/time.c:131:3: error: implicit declaration of function ‘kfree’
>> [-Werror=implicit-function-declaration]
>>    kfree(runstate_delta);
>>    ^
>> cc1: some warnings being treated as errors
>>
>> About the 1st issue, should I submit a new patch including <linux/slab.h> or
>> just a incremental based on previous patch merged into your own branch
>> /tree?
>>
>> -------------------------------------------------------------
>>
>> 2nd issue:
>>
>> aarch64-linux-gnu-gcc expects a cast for kmalloc_array(). Is this really
>> necessary as I did find people casting the return type of
>> kmalloc/kcalloc/kmalloc_array in linux source code (e.g.,
>> drivers/block/virtio_blk.c). Can we just ignore this warning?
>>
>> drivers/xen/time.c:94:18: warning: assignment makes pointer from integer without
>> a cast [-Wint-conversion]
>>    runstate_delta = kmalloc_array(num_possible_cpus(),
>>                   ^
>> -------------------------------------------------------------
> 
> That's because you need to declare kmalloc_array(), otherwise the
> compiler by default assumes that it returns an int. So including
> linux/slab.h should take care of both warnings.
> 
> I can add it while committing.

Please help add it while committing. Thank you very much for your help!

> 
> 
> -boris
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@...ts.xen.org
> https://lists.xen.org/xen-devel
> 

Dongli Zhang