[1/2] dmaengine: cppi41: Fix list not empty warning on runtime suspend

Message ID 20170104160301.22406-2-abailon@baylibre.com
State New
Headers show

Commit Message

Alexandre Bailon Jan. 4, 2017, 4:03 p.m.
Sometime, a transfer may not be queued due to a race between runtime pm
and cppi41_dma_issue_pending().
Sometime, cppi41_runtime_resume() may be interrupted right before to
update device PM state to RESUMED.
When it happens, if a new dma transfer is issued, because the device is not
in active state, the descriptor will be added to the pendding list.
But because the descriptors in the pendding list are only queued to cppi41
on runtime resume, the descriptor will not be queued.
On runtime suspend, the list is not empty, which is causing a warning.
Queue the descriptor if the device is active or resuming.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>

---
 drivers/dma/cppi41.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

-- 
2.10.2

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Comments

Andy Shevchenko Jan. 6, 2017, 8:55 p.m. | #1
On Wed, Jan 4, 2017 at 6:03 PM, Alexandre Bailon <abailon@baylibre.com> wrote:
> Sometime, a transfer may not be queued due to a race between runtime pm

> and cppi41_dma_issue_pending().

> Sometime, cppi41_runtime_resume() may be interrupted right before to

> update device PM state to RESUMED.

> When it happens, if a new dma transfer is issued, because the device is not

> in active state, the descriptor will be added to the pendding list.

> But because the descriptors in the pendding list are only queued to cppi41

> on runtime resume, the descriptor will not be queued.

> On runtime suspend, the list is not empty, which is causing a warning.

> Queue the descriptor if the device is active or resuming.


> -       if (likely(pm_runtime_active(cdd->ddev.dev)))

> +       active = pm_runtime_active(cdd->ddev.dev);

> +       if (!active) {

> +               /*

> +                * Runtime resume may be interrupted before runtime_status

> +                * has been updated. Test if device has resumed.

> +                */

> +               if (error == -EINPROGRESS) {

> +                       spin_lock_irqsave(&cdd->lock, flags);


> +                       if (list_empty(&cdd->pending))

> +                               active = true;


active = !!list_empty();

> +                       spin_unlock_irqrestore(&cdd->lock, flags);

> +               }

> +       }

> +

> +       if (likely(active))

>                 push_desc_queue(c);

>         else

>                 pending_desc(c);


-- 
With Best Regards,
Andy Shevchenko
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Patch hide | download patch | download mbox

diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
index 70d2bf7..dfc880a 100644
--- a/drivers/dma/cppi41.c
+++ b/drivers/dma/cppi41.c
@@ -545,6 +545,8 @@  static void cppi41_dma_issue_pending(struct dma_chan *chan)
 {
 	struct cppi41_channel *c = to_cpp41_chan(chan);
 	struct cppi41_dd *cdd = c->cdd;
+	unsigned long flags;
+	bool active;
 	int error;
 
 	error = pm_runtime_get(cdd->ddev.dev);
@@ -556,7 +558,21 @@  static void cppi41_dma_issue_pending(struct dma_chan *chan)
 		return;
 	}
 
-	if (likely(pm_runtime_active(cdd->ddev.dev)))
+	active = pm_runtime_active(cdd->ddev.dev);
+	if (!active) {
+		/*
+		 * Runtime resume may be interrupted before runtime_status
+		 * has been updated. Test if device has resumed.
+		 */
+		if (error == -EINPROGRESS) {
+			spin_lock_irqsave(&cdd->lock, flags);
+			if (list_empty(&cdd->pending))
+				active = true;
+			spin_unlock_irqrestore(&cdd->lock, flags);
+		}
+	}
+
+	if (likely(active))
 		push_desc_queue(c);
 	else
 		pending_desc(c);