On Fri, 2009-03-13 at 07:16 -0700, Atsushi Nemoto wrote:
> On Fri, 13 Mar 2009 01:19:50 +0900 (JST), Atsushi Nemoto <anemo@xxxxxxxxxxxxx> wrote:
> > Subject: dmaengine: Use chan_id provided by DMA device driver
> > From: Atsushi Nemoto <anemo@xxxxxxxxxxxxx>
> >
> > If chan_id was already given by the DMA device driver, use it.
> > Otherwise assign an incremental number for each channels.
> >
> > This allows the DMA device driver to reserve some channel ID numbers.
> ...
> > @@ -663,7 +664,9 @@ int dma_async_device_register(struct dma_device *device)
> > continue;
> > }
> >
> > - chan->chan_id = chancnt++;
> > + if (!chan->chan_id)
> > + chan->chan_id = chan_id++;
> > + chancnt++;
> > chan->dev->device.class = &dma_devclass;
> > chan->dev->device.parent = device->dev;
> > chan->dev->chan = chan;
>
> This patch will fix another potential problem. Some driver, for
> example ipu, assumes chan_id is an index of its internal array. But
> dmaengine core does not guarantee it.
>
> /* represent channels in sysfs. Probably want devs too */
> list_for_each_entry(chan, &device->channels, device_node) {
> chan->local = alloc_percpu(typeof(*chan->local));
> if (chan->local == NULL)
> continue;
> chan->dev = kzalloc(sizeof(*chan->dev), GFP_KERNEL);
> if (chan->dev == NULL) {
> free_percpu(chan->local);
> continue;
> }
>
> chan->chan_id = chancnt++;
> ...
> }
> device->chancnt = chancnt;
>
> If alloc_percpu or kzalloc failed, chan_id does not match with its
> position in device->channels list.
>
>
> And above "continue" looks buggy anyway. Keeping incomplete channels
> in device->channels list looks very dangerous...
Yes it does. Here is the proposed fix:
----->
dmaengine: fail device registration if channel registration fails
From: Dan Williams <dan.j.williams@xxxxxxxxx>
Atsushi points out:
"If alloc_percpu or kzalloc failed, chan_id does not match with its
position in device->channels list.
And above "continue" looks buggy anyway. Keeping incomplete channels
in device->channels list looks very dangerous..."
Reported-by: Atsushi Nemoto <anemo@xxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/dma/dmaengine.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index a589930..fa14e8b 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -652,13 +652,15 @@ int dma_async_device_register(struct dma_device *device)
/* represent channels in sysfs. Probably want devs too */
list_for_each_entry(chan, &device->channels, device_node) {
+ rc = -ENOMEM;
chan->local = alloc_percpu(typeof(*chan->local));
if (chan->local == NULL)
- continue;
+ goto err_out;
chan->dev = kzalloc(sizeof(*chan->dev), GFP_KERNEL);
if (chan->dev == NULL) {
free_percpu(chan->local);
- continue;
+ chan->local = NULL;
+ goto err_out;
}
chan->chan_id = chancnt++;
@@ -675,6 +677,8 @@ int dma_async_device_register(struct dma_device *device)
if (rc) {
free_percpu(chan->local);
chan->local = NULL;
+ kfree(chan->dev);
+ atomic_dec(idr_ref);
goto err_out;
}
chan->client_count = 0;
