From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH 1/3] virtio: change to_vp_device to an inlined definition
Date: Thu, 06 Dec 2012 09:58:57 +1030
Message-ID: <87vccgf58m.fsf@rustcorp.com.au>
References: <1354691009-25966-1-git-send-email-gaowanlong@cn.fujitsu.com>
	<20121205142821.1fb08cf0@samsung-9>
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To: Stephen Hemminger <shemminger@vyatta.com>, Wanlong Gao <gaowanlong@cn.fujitsu.com>
Cc: mst@redhat.com, virtualization@lists.linux-foundation.org
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Stephen Hemminger <shemminger@vyatta.com> writes:

> On Wed, 5 Dec 2012 15:03:27 +0800
> Wanlong Gao <gaowanlong@cn.fujitsu.com> wrote:
>
>> to_vp_device is worth changing to inlined definition.
>> 
>> Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
>> ---
>>  drivers/virtio/virtio_pci.c | 6 +-----
>>  1 file changed, 1 insertion(+), 5 deletions(-)
>> 
>> diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
>> index e3ecc94..7681fe3 100644
>> --- a/drivers/virtio/virtio_pci.c
>> +++ b/drivers/virtio/virtio_pci.c
>> @@ -98,11 +98,7 @@ static struct pci_device_id virtio_pci_id_table[] = {
>>  
>>  MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);
>>  
>> -/* Convert a generic virtio device to our structure */
>> -static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)
>> -{
>> -	return container_of(vdev, struct virtio_pci_device, vdev);
>> -}
>> +#define to_vp_device(_vdev) container_of(_vdev, struct virtio_pci_device, vdev)
>
> Just mark the function as inline. A macro loses type checking.

No, don't.

Inline functions in C files are *wrong*: you lose the warning should it
ever become unused.  GCC's does a pretty good job these days: certainly
better than guessing.

(Yeah yeah, there are always exceptions.  I've used inline deliberately
to avoid a tangle of #ifdefs, and sometimes gcc really does screw up).

Thanks,
Rusty.