linux-kernel - [PATCH V3] crypto: ccp - Release dma channels before dmaengine unrgister

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Message-Id: <20220901144712.1192698-1-koba.ko@canonical.com>
Date:   Thu,  1 Sep 2022 22:47:12 +0800
From:   Koba Ko <koba.ko@...onical.com>
To:     Tom Lendacky <thomas.lendacky@....com>,
        John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH V3] crypto: ccp - Release dma channels before dmaengine unrgister

A warning is shown during shutdown,

__dma_async_device_channel_unregister called while 2 clients hold a reference
WARNING: CPU: 15 PID: 1 at drivers/dma/dmaengine.c:1110 __dma_async_device_channel_unregister+0xb7/0xc0

Call dma_release_channel for occupied channles before dma_async_device_unregister.

Fixes: 54cce8ecb925 ("crypto: ccp - ccp_dmaengine_unregister release dma channels")
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Koba Ko <koba.ko@...onical.com>
Acked-by: Tom Lendacky <thomas.lendacky@....com>

---
V2: Fix the unused warning
V3: Fix the Fixes: tag.
---
 drivers/crypto/ccp/ccp-dmaengine.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/ccp/ccp-dmaengine.c b/drivers/crypto/ccp/ccp-dmaengine.c
index 7d4b4ad1db1f3..9f753cb4f5f18 100644
--- a/drivers/crypto/ccp/ccp-dmaengine.c
+++ b/drivers/crypto/ccp/ccp-dmaengine.c
@@ -641,6 +641,10 @@ static void ccp_dma_release(struct ccp_device *ccp)
 	for (i = 0; i < ccp->cmd_q_count; i++) {
 		chan = ccp->ccp_dma_chan + i;
 		dma_chan = &chan->dma_chan;
+
+		if (dma_chan->client_count)
+			dma_release_channel(dma_chan);
+
 		tasklet_kill(&chan->cleanup_tasklet);
 		list_del_rcu(&dma_chan->device_node);
 	}
@@ -766,8 +770,8 @@ void ccp_dmaengine_unregister(struct ccp_device *ccp)
 	if (!dmaengine)
 		return;
 
-	dma_async_device_unregister(dma_dev);
 	ccp_dma_release(ccp);
+	dma_async_device_unregister(dma_dev);
 
 	kmem_cache_destroy(ccp->dma_desc_cache);
 	kmem_cache_destroy(ccp->dma_cmd_cache);
-- 
2.25.1