linux-kernel - [PATCH v2] dmatest: properly handle duplicate DMA channels

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Message-Id: <1221754217-26974-1-git-send-email-timur@freescale.com>
Date:	Thu, 18 Sep 2008 11:10:17 -0500
From:	Timur Tabi <timur@...escale.com>
To:	dan.j.williams@...el.com, haavard.skinnemoen@...el.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] dmatest: properly handle duplicate DMA channels

Update the the dmatest driver so that it handles duplicate DMA channels
properly.

When a DMA client is notified of an available DMA channel, it must check if it
has already allocated resources for that channel.  If so, it should return
DMA_DUP.  This can happen, for example, if a DMA driver calls
dma_async_device_register() more than once.

Signed-off-by: Timur Tabi <timur@...escale.com>
---

Replaced list_for_each_entry_safe() with list_for_each_entry()

 drivers/dma/dmatest.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index a08d197..422500c 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -325,6 +325,11 @@ static enum dma_state_client dmatest_add_channel(struct dma_chan *chan)
 	struct dmatest_thread	*thread;
 	unsigned int		i;
 
+	/* Have we already been told about this channel? */
+	list_for_each_entry(dtc, &dmatest_channels, node)
+		if (dtc->chan == chan)
+			return DMA_DUP;
+
 	dtc = kmalloc(sizeof(struct dmatest_chan), GFP_ATOMIC);
 	if (!dtc) {
 		pr_warning("dmatest: No memory for %s\n", chan->dev.bus_id);
-- 
1.5.5

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