linux-kernel - Re: [PATCH] HID: usbhid: Use GFP_KERNEL instead of GFP

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Message-ID: <5D42B98B.40900@bfs.de>
Date:   Thu, 01 Aug 2019 12:06:03 +0200
From:   walter harms <wharms@....de>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
CC:     jikos@...nel.org, benjamin.tissoires@...hat.com,
        linux-usb@...r.kernel.org, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
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 <christophe.jaillet@...adoo.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 ?

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;
>