2019-08-01 07:54:09

by Christophe JAILLET

Subject: [PATCH] HID: usbhid: Use GFP_KERNEL instead of GFP_ATOMIC when applicable

There is no need to use GFP_ATOMIC when calling 'usb_alloc_coherent()'
here. These calls are done from probe functions and using GFP_KERNEL should
be safe.
The memory itself is used within some interrupts, but it is not a
problem, once it has been allocated.

Signed-off-by: Christophe JAILLET <[email protected]>
---
drivers/hid/usbhid/usbkbd.c | 4 ++--
drivers/hid/usbhid/usbmouse.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/usbhid/usbkbd.c b/drivers/hid/usbhid/usbkbd.c
index d5b7a696a68c..63e8ef8beb45 100644
--- a/drivers/hid/usbhid/usbkbd.c
+++ b/drivers/hid/usbhid/usbkbd.c
@@ -239,11 +239,11 @@ static int usb_kbd_alloc_mem(struct usb_device *dev, struct usb_kbd *kbd)
return -1;
if (!(kbd->led = usb_alloc_urb(0, GFP_KERNEL)))
return -1;
- if (!(kbd->new = usb_alloc_coherent(dev, 8, GFP_ATOMIC, &kbd->new_dma)))
+ if (!(kbd->new = usb_alloc_coherent(dev, 8, GFP_KERNEL, &kbd->new_dma)))
return -1;
if (!(kbd->cr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL)))
return -1;
- if (!(kbd->leds = usb_alloc_coherent(dev, 1, GFP_ATOMIC, &kbd->leds_dma)))
+ if (!(kbd->leds = usb_alloc_coherent(dev, 1, GFP_KERNEL, &kbd->leds_dma)))
return -1;

return 0;
diff --git a/drivers/hid/usbhid/usbmouse.c b/drivers/hid/usbhid/usbmouse.c
index 073127e65ac1..c89332017d5d 100644
--- a/drivers/hid/usbhid/usbmouse.c
+++ b/drivers/hid/usbhid/usbmouse.c
@@ -130,7 +130,7 @@ static int usb_mouse_probe(struct usb_interface *intf, const struct usb_device_i
if (!mouse || !input_dev)
goto fail1;

- mouse->data = usb_alloc_coherent(dev, 8, GFP_ATOMIC, &mouse->data_dma);
+ mouse->data = usb_alloc_coherent(dev, 8, GFP_KERNEL, &mouse->data_dma);
if (!mouse->data)
goto fail1;

--
2.20.1

2019-08-01 10:07:04

by walter harms

Subject: Re: [PATCH] HID: usbhid: Use GFP_KERNEL instead of GFP_ATOMIC when applicable

Am 01.08.2019 09:47, schrieb Christophe JAILLET:
> There is no need to use GFP_ATOMIC when calling 'usb_alloc_coherent()'
> here. These calls are done from probe functions and using GFP_KERNEL should
> be safe.
> The memory itself is used within some interrupts, but it is not a
> problem, once it has been allocated.
>
> Signed-off-by: Christophe JAILLET <[email protected]>
> ---
> drivers/hid/usbhid/usbkbd.c | 4 ++--
> drivers/hid/usbhid/usbmouse.c | 2 +-
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hid/usbhid/usbkbd.c b/drivers/hid/usbhid/usbkbd.c
> index d5b7a696a68c..63e8ef8beb45 100644
> --- a/drivers/hid/usbhid/usbkbd.c
> +++ b/drivers/hid/usbhid/usbkbd.c
> @@ -239,11 +239,11 @@ static int usb_kbd_alloc_mem(struct usb_device *dev, struct usb_kbd *kbd)
> return -1;
> if (!(kbd->led = usb_alloc_urb(0, GFP_KERNEL)))
> return -1;
> - if (!(kbd->new = usb_alloc_coherent(dev, 8, GFP_ATOMIC, &kbd->new_dma)))
> + if (!(kbd->new = usb_alloc_coherent(dev, 8, GFP_KERNEL, &kbd->new_dma)))
> return -1;
> if (!(kbd->cr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL)))
> return -1;
> - if (!(kbd->leds = usb_alloc_coherent(dev, 1, GFP_ATOMIC, &kbd->leds_dma)))
> + if (!(kbd->leds = usb_alloc_coherent(dev, 1, GFP_KERNEL, &kbd->leds_dma)))
> return -1;
>

the kernel style is usually:
kbd->new = usb_alloc_coherent(dev, 8, GFP_ATOMIC, &kbd->new_dma);
if (!kbd->new)
return -1;


in usbmouse.c this is done, any reason for the change here ?

re,
wh

> return 0;
> diff --git a/drivers/hid/usbhid/usbmouse.c b/drivers/hid/usbhid/usbmouse.c
> index 073127e65ac1..c89332017d5d 100644
> --- a/drivers/hid/usbhid/usbmouse.c
> +++ b/drivers/hid/usbhid/usbmouse.c
> @@ -130,7 +130,7 @@ static int usb_mouse_probe(struct usb_interface *intf, const struct usb_device_i
> if (!mouse || !input_dev)
> goto fail1;
>
> - mouse->data = usb_alloc_coherent(dev, 8, GFP_ATOMIC, &mouse->data_dma);
> + mouse->data = usb_alloc_coherent(dev, 8, GFP_KERNEL, &mouse->data_dma);
> if (!mouse->data)
> goto fail1;
>

2019-08-01 14:43:38

by Greg KH

Subject: Re: [PATCH] HID: usbhid: Use GFP_KERNEL instead of GFP_ATOMIC when applicable

On Thu, Aug 01, 2019 at 12:06:03PM +0200, walter harms wrote:
>
>
> Am 01.08.2019 09:47, schrieb Christophe JAILLET:
> > There is no need to use GFP_ATOMIC when calling 'usb_alloc_coherent()'
> > here. These calls are done from probe functions and using GFP_KERNEL should
> > be safe.
> > The memory itself is used within some interrupts, but it is not a
> > problem, once it has been allocated.
> >
> > Signed-off-by: Christophe JAILLET <[email protected]>
> > ---
> > drivers/hid/usbhid/usbkbd.c | 4 ++--
> > drivers/hid/usbhid/usbmouse.c | 2 +-
> > 2 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/hid/usbhid/usbkbd.c b/drivers/hid/usbhid/usbkbd.c
> > index d5b7a696a68c..63e8ef8beb45 100644
> > --- a/drivers/hid/usbhid/usbkbd.c
> > +++ b/drivers/hid/usbhid/usbkbd.c
> > @@ -239,11 +239,11 @@ static int usb_kbd_alloc_mem(struct usb_device *dev, struct usb_kbd *kbd)
> > return -1;
> > if (!(kbd->led = usb_alloc_urb(0, GFP_KERNEL)))
> > return -1;
> > - if (!(kbd->new = usb_alloc_coherent(dev, 8, GFP_ATOMIC, &kbd->new_dma)))
> > + if (!(kbd->new = usb_alloc_coherent(dev, 8, GFP_KERNEL, &kbd->new_dma)))
> > return -1;
> > if (!(kbd->cr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL)))
> > return -1;
> > - if (!(kbd->leds = usb_alloc_coherent(dev, 1, GFP_ATOMIC, &kbd->leds_dma)))
> > + if (!(kbd->leds = usb_alloc_coherent(dev, 1, GFP_KERNEL, &kbd->leds_dma)))
> > return -1;
> >
>
> the kernel style is usually:
> kbd->new = usb_alloc_coherent(dev, 8, GFP_ATOMIC, &kbd->new_dma);
> if (!kbd->new)
> return -1;
>
>
> in usbmouse.c this is done, any reason for the change here ?

If you want to be extra-correct, don't return -1, return -ENOMEM.

thanks,

greg k-h

2019-08-02 09:33:13

by Christophe JAILLET

Subject: Re: [PATCH] HID: usbhid: Use GFP_KERNEL instead of GFP_ATOMIC when applicable

Hi, (and sorry if you receive this email twice. I've used a web mail
which sends HTML by default and it was rejected by ML)

Le 01/08/2019 à 12:06, walter harms a écrit :
>
>
> Am 01.08.2019 09:47, schrieb Christophe JAILLET:
>> There is no need to use GFP_ATOMIC when calling 'usb_alloc_coherent()'
>> here. These calls are done from probe functions and using GFP_KERNEL should
>> be safe.
>> The memory itself is used within some interrupts, but it is not a
>> problem, once it has been allocated.
>>
>> Signed-off-by: Christophe JAILLET <[email protected]>
>> ---
>> drivers/hid/usbhid/usbkbd.c | 4 ++--
>> drivers/hid/usbhid/usbmouse.c | 2 +-
>> 2 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/hid/usbhid/usbkbd.c b/drivers/hid/usbhid/usbkbd.c
>> index d5b7a696a68c..63e8ef8beb45 100644
>> --- a/drivers/hid/usbhid/usbkbd.c
>> +++ b/drivers/hid/usbhid/usbkbd.c
>> @@ -239,11 +239,11 @@ static int usb_kbd_alloc_mem(struct usb_device *dev, struct usb_kbd *kbd)
>> return -1;
>> if (!(kbd->led = usb_alloc_urb(0, GFP_KERNEL)))
>> return -1;
>> - if (!(kbd->new = usb_alloc_coherent(dev, 8, GFP_ATOMIC, &kbd->new_dma)))
>> + if (!(kbd->new = usb_alloc_coherent(dev, 8, GFP_KERNEL, &kbd->new_dma)))
>> return -1;
>> if (!(kbd->cr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL)))
>> return -1;
>> - if (!(kbd->leds = usb_alloc_coherent(dev, 1, GFP_ATOMIC, &kbd->leds_dma)))
>> + if (!(kbd->leds = usb_alloc_coherent(dev, 1, GFP_KERNEL, &kbd->leds_dma)))
>> return -1;
>>
>
> the kernel style is usually:
> kbd->new = usb_alloc_coherent(dev, 8, GFP_ATOMIC, &kbd->new_dma);
> if (!kbd->new)
> return -1;
>

Searching with coccinelle with:
* x = usb_alloc_coherent(..., <+... GFP_KERNEL ...+>, ...);
finds 67 files,

whereas:
* x = usb_alloc_coherent(..., <+... GFP_ATOMIC ...+>, ...);
only finds 11 files.

>
> in usbmouse.c this is done, any reason for the change here ?
>

No real reason in fact, just to be consistent with surrounding code.

Unless some allocations are done within a spin_lock/spin_unlock, using
both GFP_KERNEL and GFP_ATOMIC in the same function looks spurious to me.
Either there is a bug (GFP_KERNEL should be GFP_ATOMIC), or a useless
constraint is given to the memory allocator.

CJ

> re,
> wh
>
>> return 0;
>> diff --git a/drivers/hid/usbhid/usbmouse.c b/drivers/hid/usbhid/usbmouse.c
>> index 073127e65ac1..c89332017d5d 100644
>> --- a/drivers/hid/usbhid/usbmouse.c
>> +++ b/drivers/hid/usbhid/usbmouse.c
>> @@ -130,7 +130,7 @@ static int usb_mouse_probe(struct usb_interface *intf, const struct usb_device_i
>> if (!mouse || !input_dev)
>> goto fail1;
>>
>> - mouse->data = usb_alloc_coherent(dev, 8, GFP_ATOMIC, &mouse->data_dma);
>> + mouse->data = usb_alloc_coherent(dev, 8, GFP_KERNEL, &mouse->data_dma);
>> if (!mouse->data)
>> goto fail1;
>>
>