linux-kernel - [PATCH 4.9 33/51] dmaengine: cppi41: delete channel from pending list when stop channel

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Date:   Tue, 11 Dec 2018 16:41:41 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Bin Liu <b-liu@...com>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Vinod Koul <vkoul@...nel.org>
Subject: [PATCH 4.9 33/51] dmaengine: cppi41: delete channel from pending list when stop channel

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bin Liu <b-liu@...com>

commit 59861547ec9a9736e7882f6fb0c096a720ff811a upstream.

The driver defines three states for a cppi channel.
- idle: .chan_busy == 0 && not in .pending list
- pending: .chan_busy == 0 && in .pending list
- busy: .chan_busy == 1 && not in .pending list

There are cases in which the cppi channel could be in the pending state
when cppi41_dma_issue_pending() is called after cppi41_runtime_suspend()
is called.

cppi41_stop_chan() has a bug for these cases to set channels to idle state.
It only checks the .chan_busy flag, but not the .pending list, then later
when cppi41_runtime_resume() is called the channels in .pending list will
be transitioned to busy state.

Removing channels from the .pending list solves the problem.

Fixes: 975faaeb9985 ("dma: cppi41: start tear down only if channel is busy")
Cc: stable@...r.kernel.org # v3.15+
Signed-off-by: Bin Liu <b-liu@...com>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@...com>
Signed-off-by: Vinod Koul <vkoul@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/dma/cppi41.c |   16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

--- a/drivers/dma/cppi41.c
+++ b/drivers/dma/cppi41.c
@@ -717,8 +717,22 @@ static int cppi41_stop_chan(struct dma_c
 
 	desc_phys = lower_32_bits(c->desc_phys);
 	desc_num = (desc_phys - cdd->descs_phys) / sizeof(struct cppi41_desc);
-	if (!cdd->chan_busy[desc_num])
+	if (!cdd->chan_busy[desc_num]) {
+		struct cppi41_channel *cc, *_ct;
+
+		/*
+		 * channels might still be in the pendling list if
+		 * cppi41_dma_issue_pending() is called after
+		 * cppi41_runtime_suspend() is called
+		 */
+		list_for_each_entry_safe(cc, _ct, &cdd->pending, node) {
+			if (cc != c)
+				continue;
+			list_del(&cc->node);
+			break;
+		}
 		return 0;
+	}
 
 	ret = cppi41_tear_down_chan(c);
 	if (ret)