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From: Halil Pasic <pasic@linux.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: Michael Mueller <mimu@linux.ibm.com>,
	KVM Mailing List <kvm@vger.kernel.org>,
	Linux-S390 Mailing List <linux-s390@vger.kernel.org>,
	Sebastian Ott <sebott@linux.ibm.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	virtualization@lists.linux-foundation.org,
	"Michael S . Tsirkin" <mst@redhat.com>,
	Christoph Hellwig <hch@infradead.org>,
	Thomas Huth <thuth@redhat.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Viktor Mihajlovski <mihajlov@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	Farhan Ali <alifm@linux.ibm.com>,
	Eric Farman <farman@linux.ibm.com>
Subject: Re: [PATCH v3 7/8] virtio/s390: use DMA memory for ccw I/O and classic notifiers
Date: Tue, 4 Jun 2019 16:29:09 +0200	[thread overview]
Message-ID: <20190604162909.54de39fb.pasic@linux.ibm.com> (raw)
In-Reply-To: <20190604153625.6c03c232.cohuck@redhat.com>

On Tue, 4 Jun 2019 15:36:25 +0200
Cornelia Huck <cohuck@redhat.com> wrote:

> On Tue, 4 Jun 2019 15:08:19 +0200
> Halil Pasic <pasic@linux.ibm.com> wrote:
> 

[..]

> 
> Two things:
> - The call path goes from the vcdev to the vdev, then back to the vcdev
>   and then to the cdev. Going from the vcdev to the cdev  directly
>   eliminates the roundtrip via the vdev, which I think does not add
>   anything.
> - I prefer
> 	variable = function_returning_a_pointer(...);
>   over
> 	function_setting_a_variable(..., variable);
>   The latter obscures the fact that we change the value of the
>   variable, unless named very obviously.
> 

I understand. Here it's especially bad because what looks like a
function is actually a macro so it ain't even fn(..., &variable) but
just fn(..., variable). I guess I'm a bit desensitized towards the latter
because of my c++ background.


> > 
> > I will change this for v4 as you requested. Again sorry for missing it!
> 
> np, can happen.

Thanks for the explanation. I will use

ccw_device_dma_zalloc() directly in v4.

Regards,
Halil

WARNING: multiple messages have this Message-ID (diff)
From: Halil Pasic <pasic@linux.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>,
	Linux-S390 Mailing List <linux-s390@vger.kernel.org>,
	Thomas Huth <thuth@redhat.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	KVM Mailing List <kvm@vger.kernel.org>,
	Sebastian Ott <sebott@linux.ibm.com>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	Farhan Ali <alifm@linux.ibm.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Eric Farman <farman@linux.ibm.com>,
	virtualization@lists.linux-foundation.org,
	Christoph Hellwig <hch@infradead.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Michael Mueller <mimu@linux.ibm.com>,
	Viktor Mihajlovski <mihajlov@linux.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>
Subject: Re: [PATCH v3 7/8] virtio/s390: use DMA memory for ccw I/O and classic notifiers
Date: Tue, 4 Jun 2019 16:29:09 +0200	[thread overview]
Message-ID: <20190604162909.54de39fb.pasic@linux.ibm.com> (raw)
In-Reply-To: <20190604153625.6c03c232.cohuck@redhat.com>

On Tue, 4 Jun 2019 15:36:25 +0200
Cornelia Huck <cohuck@redhat.com> wrote:

> On Tue, 4 Jun 2019 15:08:19 +0200
> Halil Pasic <pasic@linux.ibm.com> wrote:
> 

[..]

> 
> Two things:
> - The call path goes from the vcdev to the vdev, then back to the vcdev
>   and then to the cdev. Going from the vcdev to the cdev  directly
>   eliminates the roundtrip via the vdev, which I think does not add
>   anything.
> - I prefer
> 	variable = function_returning_a_pointer(...);
>   over
> 	function_setting_a_variable(..., variable);
>   The latter obscures the fact that we change the value of the
>   variable, unless named very obviously.
> 

I understand. Here it's especially bad because what looks like a
function is actually a macro so it ain't even fn(..., &variable) but
just fn(..., variable). I guess I'm a bit desensitized towards the latter
because of my c++ background.


> > 
> > I will change this for v4 as you requested. Again sorry for missing it!
> 
> np, can happen.

Thanks for the explanation. I will use

ccw_device_dma_zalloc() directly in v4.

Regards,
Halil

  reply	other threads:[~2019-06-04 14:29 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-29 12:26 [PATCH v3 0/8] s390: virtio: support protected virtualization Michael Mueller
2019-05-29 12:26 ` Michael Mueller
2019-05-29 12:26 ` [PATCH v3 1/8] s390/mm: force swiotlb for " Michael Mueller
2019-05-29 12:26   ` Michael Mueller
2019-05-29 12:26 ` [PATCH v3 2/8] s390/cio: introduce DMA pools to cio Michael Mueller
2019-05-29 12:26   ` Michael Mueller
2019-06-03 11:37   ` Cornelia Huck
2019-06-03 11:37     ` Cornelia Huck
2019-06-03 12:09     ` Michael Mueller
2019-06-03 12:09       ` Michael Mueller
2019-06-03 12:57       ` Halil Pasic
2019-06-03 12:57         ` Halil Pasic
2019-06-03 13:34         ` Cornelia Huck
2019-06-03 13:34           ` Cornelia Huck
2019-06-03 13:43           ` Michael Mueller
2019-06-03 13:43             ` Michael Mueller
2019-06-03 14:04       ` Halil Pasic
2019-06-03 14:04         ` Halil Pasic
2019-06-03 14:22         ` Halil Pasic
2019-06-03 14:22           ` Halil Pasic
2019-06-03 12:47     ` Halil Pasic
2019-06-03 12:47       ` Halil Pasic
2019-06-03 13:40       ` Cornelia Huck
2019-06-03 13:40         ` Cornelia Huck
2019-05-29 12:26 ` [PATCH v3 3/8] s390/cio: add basic protected virtualization support Michael Mueller
2019-05-29 12:26   ` Michael Mueller
2019-06-03 12:06   ` Cornelia Huck
2019-06-03 12:06     ` Cornelia Huck
2019-06-03 12:45     ` Michael Mueller
2019-06-03 12:45       ` Michael Mueller
2019-06-03 13:42       ` Cornelia Huck
2019-06-03 13:42         ` Cornelia Huck
2019-06-03 13:52         ` Michael Mueller
2019-06-03 13:52           ` Michael Mueller
2019-05-29 12:26 ` [PATCH v3 4/8] s390/airq: use DMA memory for adapter interrupts Michael Mueller
2019-05-29 12:26   ` Michael Mueller
2019-06-03 15:27   ` Cornelia Huck
2019-06-03 15:27     ` Cornelia Huck
2019-06-04 13:22     ` Halil Pasic
2019-06-04 13:22       ` Halil Pasic
2019-06-04 14:51       ` Cornelia Huck
2019-06-04 14:51         ` Cornelia Huck
2019-06-04 15:06         ` Halil Pasic
2019-06-04 15:06           ` Halil Pasic
2019-05-29 12:26 ` [PATCH v3 5/8] virtio/s390: use cacheline aligned airq bit vectors Michael Mueller
2019-05-29 12:26   ` Michael Mueller
2019-06-03  9:10   ` Christian Borntraeger
2019-06-03  9:10     ` Christian Borntraeger
2019-06-03 15:40   ` Cornelia Huck
2019-06-03 15:40     ` Cornelia Huck
2019-05-29 12:26 ` [PATCH v3 6/8] virtio/s390: add indirection to indicators access Michael Mueller
2019-05-29 12:26   ` Michael Mueller
2019-06-03 15:55   ` Cornelia Huck
2019-06-03 15:55     ` Cornelia Huck
2019-06-03 17:55     ` Halil Pasic
2019-06-03 17:55       ` Halil Pasic
2019-05-29 12:26 ` [PATCH v3 7/8] virtio/s390: use DMA memory for ccw I/O and classic notifiers Michael Mueller
2019-05-29 12:26   ` Michael Mueller
2019-06-03 16:17   ` Cornelia Huck
2019-06-03 16:17     ` Cornelia Huck
2019-06-04 13:08     ` Halil Pasic
2019-06-04 13:08       ` Halil Pasic
2019-06-04 13:36       ` Cornelia Huck
2019-06-04 13:36         ` Cornelia Huck
2019-06-04 14:29         ` Halil Pasic [this message]
2019-06-04 14:29           ` Halil Pasic
2019-05-29 12:26 ` [PATCH v3 8/8] virtio/s390: make airq summary indicators DMA Michael Mueller
2019-05-29 12:26   ` Michael Mueller
2019-06-03 16:03   ` Cornelia Huck
2019-06-03 16:03     ` Cornelia Huck
2019-06-03 17:54     ` Halil Pasic
2019-06-03 17:54       ` Halil Pasic

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