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Subject[PATCH v2 09/16] dmaengine: bcm-sba-raid: Improve sba_issue_pending() run duration
Date
The pending sba_request list can become very long in real-life usage
(e.g. setting up RAID array) which can cause sba_issue_pending() to
run for long duration.

This patch adds common sba_process_deferred_requests() to process
few completed and pending requests so that it finishes in short
duration. We use this common sba_process_deferred_requests() in
both sba_issue_pending() and sba_receive_message().

Signed-off-by: Anup Patel <anup.patel@broadcom.com>
---
drivers/dma/bcm-sba-raid.c | 234 ++++++++++++++++++++++++---------------------
1 file changed, 125 insertions(+), 109 deletions(-)

diff --git a/drivers/dma/bcm-sba-raid.c b/drivers/dma/bcm-sba-raid.c
index af6cc8e..f6616da 100644
--- a/drivers/dma/bcm-sba-raid.c
+++ b/drivers/dma/bcm-sba-raid.c
@@ -277,38 +277,28 @@ static void _sba_free_request(struct sba_device *sba,
sba->reqs_fence = false;
}

-static void sba_received_request(struct sba_request *req)
+/* Note: Must be called with sba->reqs_lock held */
+static void _sba_complete_request(struct sba_device *sba,
+ struct sba_request *req)
{
- unsigned long flags;
- struct sba_device *sba = req->sba;
-
- spin_lock_irqsave(&sba->reqs_lock, flags);
+ lockdep_assert_held(&sba->reqs_lock);
req->flags &= ~SBA_REQUEST_STATE_MASK;
- req->flags |= SBA_REQUEST_STATE_RECEIVED;
- list_move_tail(&req->node, &sba->reqs_received_list);
- spin_unlock_irqrestore(&sba->reqs_lock, flags);
+ req->flags |= SBA_REQUEST_STATE_COMPLETED;
+ list_move_tail(&req->node, &sba->reqs_completed_list);
+ if (list_empty(&sba->reqs_active_list))
+ sba->reqs_fence = false;
}

-static void sba_complete_chained_requests(struct sba_request *req)
+/* Note: Must be called with sba->reqs_lock held */
+static void _sba_received_request(struct sba_device *sba,
+ struct sba_request *req)
{
- unsigned long flags;
- struct sba_request *nreq;
- struct sba_device *sba = req->sba;
-
- spin_lock_irqsave(&sba->reqs_lock, flags);
-
+ lockdep_assert_held(&sba->reqs_lock);
req->flags &= ~SBA_REQUEST_STATE_MASK;
- req->flags |= SBA_REQUEST_STATE_COMPLETED;
- list_move_tail(&req->node, &sba->reqs_completed_list);
- list_for_each_entry(nreq, &req->next, next) {
- nreq->flags &= ~SBA_REQUEST_STATE_MASK;
- nreq->flags |= SBA_REQUEST_STATE_COMPLETED;
- list_move_tail(&nreq->node, &sba->reqs_completed_list);
- }
+ req->flags |= SBA_REQUEST_STATE_RECEIVED;
+ list_move_tail(&req->node, &sba->reqs_received_list);
if (list_empty(&sba->reqs_active_list))
sba->reqs_fence = false;
-
- spin_unlock_irqrestore(&sba->reqs_lock, flags);
}

static void sba_free_chained_requests(struct sba_request *req)
@@ -386,26 +376,6 @@ static void sba_cleanup_pending_requests(struct sba_device *sba)
spin_unlock_irqrestore(&sba->reqs_lock, flags);
}

-/* ====== DMAENGINE callbacks ===== */
-
-static void sba_free_chan_resources(struct dma_chan *dchan)
-{
- /*
- * Channel resources are pre-alloced so we just free-up
- * whatever we can so that we can re-use pre-alloced
- * channel resources next time.
- */
- sba_cleanup_nonpending_requests(to_sba_device(dchan));
-}
-
-static int sba_device_terminate_all(struct dma_chan *dchan)
-{
- /* Cleanup all pending requests */
- sba_cleanup_pending_requests(to_sba_device(dchan));
-
- return 0;
-}
-
static int sba_send_mbox_request(struct sba_device *sba,
struct sba_request *req)
{
@@ -431,17 +401,27 @@ static int sba_send_mbox_request(struct sba_device *sba,
return 0;
}

-static void sba_issue_pending(struct dma_chan *dchan)
+static void sba_process_deferred_requests(struct sba_device *sba)
{
int ret;
+ u32 count;
unsigned long flags;
- struct sba_request *req, *req1;
- struct sba_device *sba = to_sba_device(dchan);
+ struct sba_request *req;
+ struct dma_async_tx_descriptor *tx;

spin_lock_irqsave(&sba->reqs_lock, flags);

- /* Process all pending request */
- list_for_each_entry_safe(req, req1, &sba->reqs_pending_list, node) {
+ /* Count pending requests */
+ count = 0;
+ list_for_each_entry(req, &sba->reqs_pending_list, node)
+ count++;
+
+ /* Process pending requests */
+ while (!list_empty(&sba->reqs_pending_list) && count) {
+ /* Get the first pending request */
+ req = list_first_entry(&sba->reqs_pending_list,
+ struct sba_request, node);
+
/* Try to make request active */
if (!_sba_active_request(sba, req))
break;
@@ -456,11 +436,102 @@ static void sba_issue_pending(struct dma_chan *dchan)
_sba_pending_request(sba, req);
break;
}
+
+ count--;
+ }
+
+ /* Count completed requests */
+ count = 0;
+ list_for_each_entry(req, &sba->reqs_completed_list, node)
+ count++;
+
+ /* Process completed requests */
+ while (!list_empty(&sba->reqs_completed_list) && count) {
+ req = list_first_entry(&sba->reqs_completed_list,
+ struct sba_request, node);
+ list_del_init(&req->node);
+ tx = &req->tx;
+
+ spin_unlock_irqrestore(&sba->reqs_lock, flags);
+
+ WARN_ON(tx->cookie < 0);
+ if (tx->cookie > 0) {
+ dma_cookie_complete(tx);
+ dmaengine_desc_get_callback_invoke(tx, NULL);
+ dma_descriptor_unmap(tx);
+ tx->callback = NULL;
+ tx->callback_result = NULL;
+ }
+
+ dma_run_dependencies(tx);
+
+ spin_lock_irqsave(&sba->reqs_lock, flags);
+
+ /* If waiting for 'ack' then move to completed list */
+ if (!async_tx_test_ack(&req->tx))
+ _sba_complete_request(sba, req);
+ else
+ _sba_free_request(sba, req);
+
+ count--;
}

+ /* Re-check pending and completed work */
+ count = 0;
+ if (!list_empty(&sba->reqs_pending_list) ||
+ !list_empty(&sba->reqs_completed_list))
+ count = 1;
+
spin_unlock_irqrestore(&sba->reqs_lock, flags);
}

+static void sba_process_received_request(struct sba_device *sba,
+ struct sba_request *req)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&sba->reqs_lock, flags);
+
+ /* Mark request as received */
+ _sba_received_request(sba, req);
+
+ /* Update request */
+ if (!atomic_dec_return(&req->first->next_pending_count))
+ _sba_complete_request(sba, req->first);
+ if (req->first != req)
+ _sba_free_request(sba, req);
+
+ spin_unlock_irqrestore(&sba->reqs_lock, flags);
+}
+
+/* ====== DMAENGINE callbacks ===== */
+
+static void sba_free_chan_resources(struct dma_chan *dchan)
+{
+ /*
+ * Channel resources are pre-alloced so we just free-up
+ * whatever we can so that we can re-use pre-alloced
+ * channel resources next time.
+ */
+ sba_cleanup_nonpending_requests(to_sba_device(dchan));
+}
+
+static int sba_device_terminate_all(struct dma_chan *dchan)
+{
+ /* Cleanup all pending requests */
+ sba_cleanup_pending_requests(to_sba_device(dchan));
+
+ return 0;
+}
+
+static void sba_issue_pending(struct dma_chan *dchan)
+{
+ struct sba_device *sba = to_sba_device(dchan);
+
+ /* Process deferred requests */
+ sba_process_deferred_requests(sba);
+}
+
static dma_cookie_t sba_tx_submit(struct dma_async_tx_descriptor *tx)
{
unsigned long flags;
@@ -1382,40 +1453,10 @@ sba_prep_dma_pq(struct dma_chan *dchan, dma_addr_t *dst, dma_addr_t *src,

/* ====== Mailbox callbacks ===== */

-static void sba_dma_tx_actions(struct sba_request *req)
-{
- struct dma_async_tx_descriptor *tx = &req->tx;
-
- WARN_ON(tx->cookie < 0);
-
- if (tx->cookie > 0) {
- dma_cookie_complete(tx);
-
- /*
- * Call the callback (must not sleep or submit new
- * operations to this channel)
- */
- if (tx->callback)
- tx->callback(tx->callback_param);
-
- dma_descriptor_unmap(tx);
- }
-
- /* Run dependent operations */
- dma_run_dependencies(tx);
-
- /* If waiting for 'ack' then move to completed list */
- if (!async_tx_test_ack(&req->tx))
- sba_complete_chained_requests(req);
- else
- sba_free_chained_requests(req);
-}
-
static void sba_receive_message(struct mbox_client *cl, void *msg)
{
- unsigned long flags;
struct brcm_message *m = msg;
- struct sba_request *req = m->ctx, *req1;
+ struct sba_request *req = m->ctx;
struct sba_device *sba = req->sba;

/* Error count if message has error */
@@ -1423,36 +1464,11 @@ static void sba_receive_message(struct mbox_client *cl, void *msg)
dev_err(sba->dev, "%s got message with error %d",
dma_chan_name(&sba->dma_chan), m->error);

- /* Mark request as received */
- sba_received_request(req);
-
- /* Wait for all chained requests to be completed */
- if (atomic_dec_return(&req->first->next_pending_count))
- goto done;
-
- /* Point to first request */
- req = req->first;
-
- /* Update request */
- if (req->flags & SBA_REQUEST_STATE_RECEIVED)
- sba_dma_tx_actions(req);
- else
- sba_free_chained_requests(req);
-
- spin_lock_irqsave(&sba->reqs_lock, flags);
-
- /* Re-check all completed request waiting for 'ack' */
- list_for_each_entry_safe(req, req1, &sba->reqs_completed_list, node) {
- spin_unlock_irqrestore(&sba->reqs_lock, flags);
- sba_dma_tx_actions(req);
- spin_lock_irqsave(&sba->reqs_lock, flags);
- }
-
- spin_unlock_irqrestore(&sba->reqs_lock, flags);
+ /* Process received request */
+ sba_process_received_request(sba, req);

-done:
- /* Try to submit pending request */
- sba_issue_pending(&sba->dma_chan);
+ /* Process deferred requests */
+ sba_process_deferred_requests(sba);
}

/* ====== Platform driver routines ===== */
--
2.7.4
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