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Subject[PATCH 28/30] rapidio/tsi721_dma: fix synchronization issues
Date
Fix synchronization issues found during testing using multiple DMA
transfer requests to the same channel:
- lost MSI-X interrupt notifications
- non-synchronized attempts to start DMA channel HW resulting in error
message from the driver
- cookie tracking/update race conditions resulting in incorrect DMA
transfer status report

Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Reported-by: Barry Wood <barry.wood@idt.com>
Tested-by: Barry Wood <barry.wood@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com>
Cc: Barry Wood <barry.wood@idt.com>
Cc: linux-kernel@vger.kernel.org
---
drivers/rapidio/devices/tsi721_dma.c | 25 ++++++++++++++++---------
1 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/rapidio/devices/tsi721_dma.c b/drivers/rapidio/devices/tsi721_dma.c
index 5bc9071..0363733 100644
--- a/drivers/rapidio/devices/tsi721_dma.c
+++ b/drivers/rapidio/devices/tsi721_dma.c
@@ -84,7 +84,7 @@ static int tsi721_bdma_ch_init(struct tsi721_bdma_chan *bdma_chan, int bd_num)
*/
bd_ptr = dma_zalloc_coherent(dev,
(bd_num + 1) * sizeof(struct tsi721_dma_desc),
- &bd_phys, GFP_KERNEL);
+ &bd_phys, GFP_ATOMIC);
if (!bd_ptr)
return -ENOMEM;

@@ -102,7 +102,7 @@ static int tsi721_bdma_ch_init(struct tsi721_bdma_chan *bdma_chan, int bd_num)
sts_size = roundup_pow_of_two(sts_size);
sts_ptr = dma_zalloc_coherent(dev,
sts_size * sizeof(struct tsi721_dma_sts),
- &sts_phys, GFP_KERNEL);
+ &sts_phys, GFP_ATOMIC);
if (!sts_ptr) {
/* Free space allocated for DMA descriptors */
dma_free_coherent(dev,
@@ -297,7 +297,8 @@ static irqreturn_t tsi721_bdma_msix(int irq, void *ptr)
{
struct tsi721_bdma_chan *bdma_chan = ptr;

- tsi721_bdma_handler(bdma_chan);
+ if (bdma_chan->active)
+ tasklet_schedule(&bdma_chan->tasklet);
return IRQ_HANDLED;
}
#endif /* CONFIG_PCI_MSI */
@@ -618,14 +619,14 @@ static void tsi721_dma_tasklet(unsigned long data)
}
list_add(&desc->desc_node, &bdma_chan->free_list);
bdma_chan->active_tx = NULL;
+ tsi721_advance_work(bdma_chan, NULL);
spin_unlock(&bdma_chan->lock);
if (callback)
callback(param);
- spin_lock(&bdma_chan->lock);
+ } else {
+ tsi721_advance_work(bdma_chan, bdma_chan->active_tx);
+ spin_unlock(&bdma_chan->lock);
}
-
- tsi721_advance_work(bdma_chan, bdma_chan->active_tx);
- spin_unlock(&bdma_chan->lock);
}

/* Re-Enable BDMA channel interrupts */
@@ -681,7 +682,7 @@ static int tsi721_alloc_chan_resources(struct dma_chan *dchan)

/* Allocate queue of transaction descriptors */
desc = kcalloc(TSI721_DMA_TX_QUEUE_SZ, sizeof(struct tsi721_tx_desc),
- GFP_KERNEL);
+ GFP_ATOMIC);
if (!desc) {
tsi_err(&dchan->dev->device,
"DMAC%d Failed to allocate logical descriptors",
@@ -744,7 +745,13 @@ static
enum dma_status tsi721_tx_status(struct dma_chan *dchan, dma_cookie_t cookie,
struct dma_tx_state *txstate)
{
- return dma_cookie_status(dchan, cookie, txstate);
+ struct tsi721_bdma_chan *bdma_chan = to_tsi721_chan(dchan);
+ enum dma_status status;
+
+ spin_lock_bh(&bdma_chan->lock);
+ status = dma_cookie_status(dchan, cookie, txstate);
+ spin_unlock_bh(&bdma_chan->lock);
+ return status;
}

static void tsi721_issue_pending(struct dma_chan *dchan)
--
1.7.8.4
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