* Re: [PATCH] HID: usbhid: Use GFP_KERNEL instead of GFP_ATOMIC when applicable
2019-08-01 10:06 ` walter harms
@ 2019-08-01 13:47 ` Greg KH
2019-08-02 7:51 ` Christophe JAILLET
1 sibling, 0 replies; 4+ messages in thread
From: Greg KH @ 2019-08-01 13:47 UTC (permalink / raw)
To: walter harms
Cc: Christophe JAILLET, jikos, benjamin.tissoires, linux-usb,
linux-input, linux-kernel, kernel-janitors
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 <christophe.jaillet@wanadoo.fr>
> > ---
> > 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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] HID: usbhid: Use GFP_KERNEL instead of GFP_ATOMIC when applicable
2019-08-01 10:06 ` walter harms
2019-08-01 13:47 ` Greg KH
@ 2019-08-02 7:51 ` Christophe JAILLET
1 sibling, 0 replies; 4+ messages in thread
From: Christophe JAILLET @ 2019-08-02 7:51 UTC (permalink / raw)
To: wharms
Cc: jikos, benjamin.tissoires, linux-usb, linux-input, linux-kernel,
kernel-janitors
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 <christophe.jaillet@wanadoo.fr>
>> ---
>> 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;
>>
>
^ permalink raw reply [flat|nested] 4+ messages in thread