Re: [RFC v02 02/15] dmaengine: core: Move and merge the code paths using private_candidate

Andy Shevchenko
2015-11-30T14:42:33Z

On Mon, Nov 30, 2015 at 3:45 PM, Peter Ujfalusi <peter.ujfalusi@ti.com> wrote:
> Channel matching with private_candidate() is used in two paths, the error
> checking is slightly different in them and they are duplicating code also.
> Move the code under dma_get_channel() to provide consistent execution and
> going to allow us to reuse this mode of channel lookup later.
>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> ---
> drivers/dma/dmaengine.c | 81 +++++++++++++++++++++++++------------------------
> 1 file changed, 42 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 52c3eee48e2e..1249165fb4b2 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -549,6 +549,42 @@ static struct dma_chan *private_candidate(const dma_cap_mask_t *mask,
> return NULL;
> }
>
> +static struct dma_chan *dma_get_channel(struct dma_device *device,

Naming scheme inside dmaengine.c looks like a mess.

Since it's static function that utilizes private_candidate() may I
propose the name like find_candidate() ?

> + const dma_cap_mask_t *mask,
> + dma_filter_fn fn, void *fn_param)
> +{
> + struct dma_chan *chan = private_candidate(mask, device, fn, fn_param);
> + int err;
> +
> + if (chan) {
> + /* Found a suitable channel, try to grab, prep, and return it.
> + * We first set DMA_PRIVATE to disable balance_ref_count as this
> + * channel will not be published in the general-purpose
> + * allocator
> + */
> + dma_cap_set(DMA_PRIVATE, device->cap_mask);
> + device->privatecnt++;
> + err = dma_chan_get(chan);
> +
> + if (err) {
> + if (err == -ENODEV) {
> + pr_debug("%s: %s module removed\n", __func__,
> + dma_chan_name(chan));
> + list_del_rcu(&device->global_node);
> + } else
> + pr_debug("%s: failed to get %s: (%d)\n",
> + __func__, dma_chan_name(chan), err);
> +
> + if (--device->privatecnt == 0)
> + dma_cap_clear(DMA_PRIVATE, device->cap_mask);
> +
> + chan = ERR_PTR(err);
> + }
> + }
> +
> + return chan ? chan : ERR_PTR(-EPROBE_DEFER);
> +}
> +
> /**
> * dma_get_slave_channel - try to get specific channel exclusively
> * @chan: target channel
> @@ -587,7 +623,6 @@ struct dma_chan *dma_get_any_slave_channel(struct dma_device *device)
> {
> dma_cap_mask_t mask;
> struct dma_chan *chan;
> - int err;
>
> dma_cap_zero(mask);
> dma_cap_set(DMA_SLAVE, mask);
> @@ -595,23 +630,11 @@ struct dma_chan *dma_get_any_slave_channel(struct dma_device *device)
> /* lock against __dma_request_channel */
> mutex_lock(&dma_list_mutex);
>
> - chan = private_candidate(&mask, device, NULL, NULL);
> - if (chan) {
> - dma_cap_set(DMA_PRIVATE, device->cap_mask);
> - device->privatecnt++;
> - err = dma_chan_get(chan);
> - if (err) {
> - pr_debug("%s: failed to get %s: (%d)\n",
> - __func__, dma_chan_name(chan), err);
> - chan = NULL;
> - if (--device->privatecnt == 0)
> - dma_cap_clear(DMA_PRIVATE, device->cap_mask);
> - }
> - }
> + chan = dma_get_channel(device, &mask, NULL, NULL);
>
> mutex_unlock(&dma_list_mutex);
>
> - return chan;
> + return IS_ERR(chan) ? NULL : chan;
> }
> EXPORT_SYMBOL_GPL(dma_get_any_slave_channel);
>
> @@ -628,35 +651,15 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
> {
> struct dma_device *device, *_d;
> struct dma_chan *chan = NULL;
> - int err;
>
> /* Find a channel */
> mutex_lock(&dma_list_mutex);
> list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
> - chan = private_candidate(mask, device, fn, fn_param);
> - if (chan) {
> - /* Found a suitable channel, try to grab, prep, and
> - * return it. We first set DMA_PRIVATE to disable
> - * balance_ref_count as this channel will not be
> - * published in the general-purpose allocator
> - */
> - dma_cap_set(DMA_PRIVATE, device->cap_mask);
> - device->privatecnt++;
> - err = dma_chan_get(chan);
> + chan = dma_get_channel(device, mask, fn, fn_param);
> + if (!IS_ERR(chan))
> + break;
>
> - if (err == -ENODEV) {
> - pr_debug("%s: %s module removed\n",
> - __func__, dma_chan_name(chan));
> - list_del_rcu(&device->global_node);
> - } else if (err)
> - pr_debug("%s: failed to get %s: (%d)\n",
> - __func__, dma_chan_name(chan), err);
> - else
> - break;
> - if (--device->privatecnt == 0)
> - dma_cap_clear(DMA_PRIVATE, device->cap_mask);
> - chan = NULL;
> - }
> + chan = NULL;
> }
> mutex_unlock(&dma_list_mutex);
>
> --
> 2.6.3
>

--
With Best Regards,
Andy Shevchenko