Commit 341198ed authored by Leonid Iziumtsev's avatar Leonid Iziumtsev Committed by Vinod Koul

dmaengine: imx-dma: fix wrong callback invoke

Once the "ld_queue" list is not empty, next descriptor will migrate
into "ld_active" list. The "desc" variable will be overwritten
during that transition. And later the dmaengine_desc_get_callback_invoke()
will use it as an argument. As result we invoke wrong callback.

That behaviour was in place since:
commit fcaaba6c ("dmaengine: imx-dma: fix callback path in tasklet").
But after commit 4cd13c21 ("softirq: Let ksoftirqd do its job")
things got worse, since possible delay between tasklet_schedule()
from DMA irq handler and actual tasklet function execution got bigger.
And that gave more time for new DMA request to be submitted and
to be put into "ld_queue" list.

It has been noticed that DMA issue is causing problems for "mxc-mmc"
driver. While stressing the system with heavy network traffic and
writing/reading to/from sd card simultaneously the timeout may happen:

10013000.sdhci: mxcmci_watchdog: read time out (status = 0x30004900)

That often lead to file system corruption.
Signed-off-by: default avatarLeonid Iziumtsev <leonid.iziumtsev@gmail.com>
Signed-off-by: Vinod Koul's avatarVinod Koul <vkoul@kernel.org>
Cc: stable@vger.kernel.org
parent dc3f595b
......@@ -618,7 +618,7 @@ static void imxdma_tasklet(unsigned long data)
{
struct imxdma_channel *imxdmac = (void *)data;
struct imxdma_engine *imxdma = imxdmac->imxdma;
struct imxdma_desc *desc;
struct imxdma_desc *desc, *next_desc;
unsigned long flags;
spin_lock_irqsave(&imxdma->lock, flags);
......@@ -648,10 +648,10 @@ static void imxdma_tasklet(unsigned long data)
list_move_tail(imxdmac->ld_active.next, &imxdmac->ld_free);
if (!list_empty(&imxdmac->ld_queue)) {
desc = list_first_entry(&imxdmac->ld_queue, struct imxdma_desc,
node);
next_desc = list_first_entry(&imxdmac->ld_queue,
struct imxdma_desc, node);
list_move_tail(imxdmac->ld_queue.next, &imxdmac->ld_active);
if (imxdma_xfer_desc(desc) < 0)
if (imxdma_xfer_desc(next_desc) < 0)
dev_warn(imxdma->dev, "%s: channel: %d couldn't xfer desc\n",
__func__, imxdmac->channel);
}
......
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