Messages in this thread | | | Date | Tue, 30 Aug 2022 10:32:46 -0500 | Subject | Re: crypto: ccp - Release dma channels before dmaengine unrgister | From | Tom Lendacky <> |
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On 8/30/22 04:34, Koba Ko wrote: > 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 > > Call dma_release_channel for occupied channles > before dma_async_device_unregister. > > Fixes: 4cbe9bc34ed0 ("crypto: ccp - ccp_dmaengine_unregister release dma channels") > Signed-off-by: Koba Ko <koba.ko@canonical.com> > --- > drivers/crypto/ccp/ccp-dmaengine.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/crypto/ccp/ccp-dmaengine.c b/drivers/crypto/ccp/ccp-dmaengine.c > index 7d4b4ad1db1f3..ba3eb1ac3b55d 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); > } > @@ -762,12 +766,14 @@ int ccp_dmaengine_register(struct ccp_device *ccp) > void ccp_dmaengine_unregister(struct ccp_device *ccp) > { > struct dma_device *dma_dev = &ccp->dma_dev; > + struct dma_chan *dma_chan; > + unsigned int i; > > if (!dmaengine) > return; > > - dma_async_device_unregister(dma_dev); > ccp_dma_release(ccp); > + dma_async_device_unregister(dma_dev);
Seems the right way to get rid of the warn, but can there still be a race where the channel is grabbed again after ccp_dma_release() and before dma_async_device_unregister() is called?
Thanks, Tom
> > kmem_cache_destroy(ccp->dma_desc_cache); > kmem_cache_destroy(ccp->dma_cmd_cache);
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