[3.11.y.z extended stable] Patch "rapidio/tsi721_dma: fix failure to obtain transaction descriptor" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Wed Aug 6 13:54:05 UTC 2014


This is a note to let you know that I have just added a patch titled

    rapidio/tsi721_dma: fix failure to obtain transaction descriptor

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From e480277ab5b33dfc4d9b50718da8d620f213c64f Mon Sep 17 00:00:00 2001
From: Alexandre Bounine <alexandre.bounine at idt.com>
Date: Wed, 30 Jul 2014 16:08:26 -0700
Subject: rapidio/tsi721_dma: fix failure to obtain transaction descriptor

commit 0193ed8225e1a79ed64632106ec3cc81798cb13c upstream.

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 <alexandre.bounine at idt.com>
Cc: Matt Porter <mporter at kernel.crashing.org>
Cc: Andre van Herk <andre.van.herk at prodrive-technologies.com>
Cc: Stef van Os <stef.van.os at prodrive-technologies.com>
Cc: Vinod Koul <vinod.koul at intel.com>
Cc: Dan Williams <dan.j.williams at intel.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/rapidio/devices/tsi721_dma.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/rapidio/devices/tsi721_dma.c b/drivers/rapidio/devices/tsi721_dma.c
index 91245f5dbe81..47257b6eea84 100644
--- a/drivers/rapidio/devices/tsi721_dma.c
+++ b/drivers/rapidio/devices/tsi721_dma.c
@@ -287,6 +287,12 @@ struct tsi721_tx_desc *tsi721_desc_get(struct tsi721_bdma_chan *bdma_chan)
 			"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(struct tsi721_bdma_chan *bdma_chan)
 	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;
--
1.9.1





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