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

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

[Jia-Ju Bai]

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>
---
 drivers/xen/xen-pciback/pci_stub.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 9e480fd..95e6ddd 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -577,7 +577,7 @@ static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)
 		}
 
 		if (!match) {
-			pci_dev_id = kmalloc(sizeof(*pci_dev_id), GFP_ATOMIC);
+			pci_dev_id = kmalloc(sizeof(*pci_dev_id), GFP_KERNEL);
 			if (!pci_dev_id) {
 				err = -ENOMEM;
 				goto out;
-- 
1.9.1

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

[Boris Ostrovsky]

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()?

-boris

> ---
>  drivers/xen/xen-pciback/pci_stub.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
> index 9e480fd..95e6ddd 100644
> --- a/drivers/xen/xen-pciback/pci_stub.c
> +++ b/drivers/xen/xen-pciback/pci_stub.c
> @@ -577,7 +577,7 @@ static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  		}
>  
>  		if (!match) {
> -			pci_dev_id = kmalloc(sizeof(*pci_dev_id), GFP_ATOMIC);
> +			pci_dev_id = kmalloc(sizeof(*pci_dev_id), GFP_KERNEL);
>  			if (!pci_dev_id) {
>  				err = -ENOMEM;
>  				goto out;

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

[Jia-Ju Bai]

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

[Boris Ostrovsky]

On 04/10/2018 10:31 AM, Jia-Ju Bai wrote:
>
>
>
> 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.

I don't see why it needs to be ATOMIC, it's sysfs access. Can you send a
patch to fix it as well?


Thanks.
-boris

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

[Jia-Ju Bai]

On 2018/4/10 23:01, Boris Ostrovsky wrote:
> On 04/10/2018 10:31 AM, Jia-Ju Bai wrote:
>>
>>
>> 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.
> I don't see why it needs to be ATOMIC, it's sysfs access. Can you send a
> patch to fix it as well?

Okay, I will send a patch for it soon.
You can have a look :)


Best wishes,
Jia-Ju Bai

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

[Boris Ostrovsky]

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>

For all 5 patches:

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

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

[Boris Ostrovsky]

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>
>


Applied the series and the extra patch to for-linus-4.17

-boris