async_tx: remove walk of tx->parent chain in dma_wait_for_async_tx
We currently walk the parent chain when waiting for a given tx to
complete however this walk may race with the driver cleanup routine.
The routines in async_raid6_recov.c may fall back to the synchronous
path at any point so we need to be prepared to call async_tx_quiesce()
(which calls dma_wait_for_async_tx). To remove the ->parent walk we
guarantee that every time a dependency is attached ->issue_pending() is
invoked, then we can simply poll the initial descriptor until
completion.
This also allows for a lighter weight 'issue pending' implementation as
there is no longer a requirement to iterate through all the channels'
->issue_pending() routines as long as operations have been submitted in
an ordered chain. async_tx_issue_pending() is added for this case.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/crypto/async_tx/async_tx.c b/crypto/async_tx/async_tx.c
index 6e37ad3..60615fe 100644
--- a/crypto/async_tx/async_tx.c
+++ b/crypto/async_tx/async_tx.c
@@ -77,8 +77,8 @@
async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
struct dma_async_tx_descriptor *tx)
{
- struct dma_chan *chan;
- struct dma_device *device;
+ struct dma_chan *chan = depend_tx->chan;
+ struct dma_device *device = chan->device;
struct dma_async_tx_descriptor *intr_tx = (void *) ~0;
/* first check to see if we can still append to depend_tx */
@@ -90,11 +90,11 @@
}
spin_unlock_bh(&depend_tx->lock);
- if (!intr_tx)
+ /* attached dependency, flush the parent channel */
+ if (!intr_tx) {
+ device->device_issue_pending(chan);
return;
-
- chan = depend_tx->chan;
- device = chan->device;
+ }
/* see if we can schedule an interrupt
* otherwise poll for completion
@@ -128,6 +128,7 @@
intr_tx->tx_submit(intr_tx);
async_tx_ack(intr_tx);
}
+ device->device_issue_pending(chan);
} else {
if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
panic("%s: DMA_ERROR waiting for depend_tx\n",
