Re: [PATCH 1/4] xen: xen-pciback: Replace GFP_ATOMIC with GFP_KERNEL in pcistub_probe - Jia-Ju Bai

From: Jia-Ju Bai <baijiaju1990@gmail.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	jgross@suse.com, gregkh@linuxfoundation.org
Cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] xen: xen-pciback: Replace GFP_ATOMIC with GFP_KERNEL in pcistub_probe
Date: Tue, 10 Apr 2018 22:31:28 +0800	[thread overview]
Message-ID: <74fe5dd3-fb85-bed8-82b6-a9fb7a3a376d@gmail.com> (raw)
In-Reply-To: <b07f0a27-f09d-1617-ab9e-ebbc761cb3a4@oracle.com>

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On 2018/4/10 22:27, Boris Ostrovsky wrote:
> On 04/09/2018 11:03 AM, Jia-Ju Bai wrote:
>> pcistub_probe() is never called in atomic context.
>> This function is only set as ".probe" in struct pci_driver.
>>
>> Despite never getting called from atomic context,
>> pcistub_probe() calls kmalloc() with GFP_ATOMIC,
>> which does not sleep for allocation.
>> GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
>> which can sleep and improve the possibility of sucessful allocation.
>>
>> This is found by a static analysis tool named DCNS written by myself.
>> And I also manually check it.
>>
>> Signed-off-by: Jia-Ju Bai<baijiaju1990@gmail.com>
> What about use of GFP_ATOMIC in pcistub_reg_add()?

Thanks for your reply :)
I find pcistub_reg_add() is called by pcistub_quirk_add().
And pcistub_quirk_add() is called in the macro DRIVER_ATTR().
I am not sure whether DRIVER_ATTR() can make the function called in 
atomic context,
so I do not analyze it in my tool.

Best wishes,
Jia-Ju Bai

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