rapidio/tsi721_dma: fix synchronization issues

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/rapidio/devices/tsi721_dma.c b/drivers/rapidio/devices/tsi721_dma.c
index 5bc9071ebcae26b3bd299fca9f2de38cec3251ed..03637330c4826dc12a4bb0fdc56688155ce7064f 100644 (file)
--- 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)