The patch titled
     Subject: rapidio/tsi721_dma: fix failure to obtain transaction descriptor
has been added to the -mm tree.  Its filename is
     rapidio-tsi721_dma-fix-failure-to-obtain-transaction-descriptor.patch

This patch should soon appear at
    
http://ozlabs.org/~akpm/mmots/broken-out/rapidio-tsi721_dma-fix-failure-to-obtain-transaction-descriptor.patch
and later at
    
http://ozlabs.org/~akpm/mmotm/broken-out/rapidio-tsi721_dma-fix-failure-to-obtain-transaction-descriptor.patch

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------------------------------------------------------
From: Alexandre Bounine <[email protected]>
Subject: rapidio/tsi721_dma: fix failure to obtain transaction descriptor

This is a bug fix for the situation when function tsi721_desc_get() fails
to obtain a free transaction descriptor.

The bug usually results in a memory access crash dump when data transfer
scatter-gather list has more entries than size of hardware buffer
descriptors ring.  This fix ensures that error is properly returned to a
caller instead of an invalid entry.

This patch is applicable to kernel versions starting from v3.5.

Signed-off-by: Alexandre Bounine <[email protected]>
Cc: Matt Porter <[email protected]>
Cc: Andre van Herk <[email protected]>
Cc: Stef van Os <[email protected]>
Cc: Vinod Koul <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: <[email protected]>    [3.5+]
Signed-off-by: Andrew Morton <[email protected]>
---

 drivers/rapidio/devices/tsi721_dma.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff -puN 
drivers/rapidio/devices/tsi721_dma.c~rapidio-tsi721_dma-fix-failure-to-obtain-transaction-descriptor
 drivers/rapidio/devices/tsi721_dma.c
--- 
a/drivers/rapidio/devices/tsi721_dma.c~rapidio-tsi721_dma-fix-failure-to-obtain-transaction-descriptor
+++ a/drivers/rapidio/devices/tsi721_dma.c
@@ -287,6 +287,12 @@ struct tsi721_tx_desc *tsi721_desc_get(s
                        "desc %p not ACKed\n", tx_desc);
        }
 
+       if (ret == NULL) {
+               dev_dbg(bdma_chan->dchan.device->dev,
+                       "%s: unable to obtain tx descriptor\n", __func__);
+               goto err_out;
+       }
+
        i = bdma_chan->wr_count_next % bdma_chan->bd_num;
        if (i == bdma_chan->bd_num - 1) {
                i = 0;
@@ -297,7 +303,7 @@ struct tsi721_tx_desc *tsi721_desc_get(s
        tx_desc->txd.phys = bdma_chan->bd_phys +
                                i * sizeof(struct tsi721_dma_desc);
        tx_desc->hw_desc = &((struct tsi721_dma_desc *)bdma_chan->bd_base)[i];
-
+err_out:
        spin_unlock_bh(&bdma_chan->lock);
 
        return ret;
_

Patches currently in -mm which might be from [email protected] are

rapidio-tsi721_dma-fix-failure-to-obtain-transaction-descriptor.patch
rapidio-add-new-rapidio-dma-interface-routines.patch

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