Re: [PATCH 3/4] dma: mxs-dma: make mxs_dma_prep_slave_sg() multiuser safe

From: Huang Shijie
Date: Thu Dec 08 2011 - 03:22:29 EST


ä 2011å12æ08æ 16:15, Lothar WaÃmann åé:
Using a static variable for counting the number of CCWs attached to
a DMA channel when appending a new descriptor is not multi user safe.

Signed-off-by: Lothar WaÃmann<LW@xxxxxxxxxxxxxxxxxxx>
---
drivers/dma/mxs-dma.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
index c7574e8..78336b0 100644
--- a/drivers/dma/mxs-dma.c
+++ b/drivers/dma/mxs-dma.c
@@ -111,6 +111,7 @@ struct mxs_dma_chan {
int chan_irq;
struct mxs_dma_ccw *ccw;
dma_addr_t ccw_phys;
+ int desc_count;
dma_cookie_t last_completed;
enum dma_status status;
unsigned int flags;
@@ -386,7 +387,7 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
struct scatterlist *sg;
int i, j;
u32 *pio;
- static int idx;
+ int idx = append ? mxs_chan->desc_count : 0;

if (mxs_chan->status == DMA_IN_PROGRESS&& !append)
return NULL;
@@ -462,6 +463,7 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
}
}
}
+ mxs_chan->desc_count = idx;

return&mxs_chan->desc;

@@ -523,6 +525,7 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_dma_cyclic(

i++;
}
+ mxs_chan->desc_count = i;

return&mxs_chan->desc;

I like this patch.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/