[PATCH AUTOSEL 4.19 117/252] dmaengine: Store module owner in dma_device struct

[PATCH AUTOSEL 4.19 117/252] dmaengine: Store module owner in dma_device struct

[Sasha Levin]

From: Logan Gunthorpe <logang@deltatee.com>

[ Upstream commit dae7a589c18a4d979d5f14b09374e871b995ceb1 ]

dma_chan_to_owner() dereferences the driver from the struct device to
obtain the owner and call module_[get|put](). However, if the backing
device is unbound before the dma_device is unregistered, the driver
will be cleared and this will cause a NULL pointer dereference.

Instead, store a pointer to the owner module in the dma_device struct
so the module reference can be properly put when the channel is put, even
if the backing device was destroyed first.

This change helps to support a safer unbind of DMA engines.
If the dma_device is unregistered in the driver's remove function,
there's no guarantee that there are no existing clients and a users
action may trigger the WARN_ONCE in dma_async_device_unregister()
which is unlikely to leave the system in a consistent state.
Instead, a better approach is to allow the backing driver to go away
and fail any subsequent requests to it.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Link: https://lore.kernel.org/r/20191216190120.21374-2-logang@deltatee.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/dma/dmaengine.c   | 4 +++-
 include/linux/dmaengine.h | 2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index f1a441ab395d7..8a52a5efee4f5 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -190,7 +190,7 @@ __dma_device_satisfies_mask(struct dma_device *device,
 
 static struct module *dma_chan_to_owner(struct dma_chan *chan)
 {
-	return chan->device->dev->driver->owner;
+	return chan->device->owner;
 }
 
 /**
@@ -923,6 +923,8 @@ int dma_async_device_register(struct dma_device *device)
 		return -EIO;
 	}
 
+	device->owner = device->dev->driver->owner;
+
 	if (dma_has_cap(DMA_MEMCPY, device->cap_mask) && !device->device_prep_dma_memcpy) {
 		dev_err(device->dev,
 			"Device claims capability %s, but op is not defined\n",
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 0647f436f88c2..50128c36f0b48 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -686,6 +686,7 @@ struct dma_filter {
  * @fill_align: alignment shift for memset operations
  * @dev_id: unique device ID
  * @dev: struct device reference for dma mapping api
+ * @owner: owner module (automatically set based on the provided dev)
  * @src_addr_widths: bit mask of src addr widths the device supports
  *	Width is specified in bytes, e.g. for a device supporting
  *	a width of 4 the mask should have BIT(4) set.
@@ -749,6 +750,7 @@ struct dma_device {
 
 	int dev_id;
 	struct device *dev;
+	struct module *owner;
 
 	u32 src_addr_widths;
 	u32 dst_addr_widths;
-- 
2.20.1

[PATCH AUTOSEL 4.19 118/252] dmaengine: imx-sdma: Fix memory leak

[Sasha Levin]

From: Sascha Hauer <s.hauer@pengutronix.de>

[ Upstream commit 02939cd167095f16328a1bd5cab5a90b550606df ]

The current descriptor is not on any list of the virtual DMA channel.
Once sdma_terminate_all() is called when a descriptor is currently
in flight then this one is forgotten to be freed. We have to call
vchan_terminate_vdesc() on this descriptor to re-add it to the lists.
Now that we also free the currently running descriptor we can (and
actually have to) remove the current descriptor from its list also
for the cyclic case.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Robin Gong <yibin.gong@nxp.com>
Tested-by: Robin Gong <yibin.gong@nxp.com>
Link: https://lore.kernel.org/r/20191216105328.15198-10-s.hauer@pengutronix.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/dma/imx-sdma.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index ceb82e74f5b4e..d66a7fdff898e 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -738,12 +738,8 @@ static void sdma_start_desc(struct sdma_channel *sdmac)
 		return;
 	}
 	sdmac->desc = desc = to_sdma_desc(&vd->tx);
-	/*
-	 * Do not delete the node in desc_issued list in cyclic mode, otherwise
-	 * the desc allocated will never be freed in vchan_dma_desc_free_list
-	 */
-	if (!(sdmac->flags & IMX_DMA_SG_LOOP))
-		list_del(&vd->node);
+
+	list_del(&vd->node);
 
 	sdma->channel_control[channel].base_bd_ptr = desc->bd_phys;
 	sdma->channel_control[channel].current_bd_ptr = desc->bd_phys;
@@ -1044,7 +1040,6 @@ static void sdma_channel_terminate_work(struct work_struct *work)
 
 	spin_lock_irqsave(&sdmac->vc.lock, flags);
 	vchan_get_all_descriptors(&sdmac->vc, &head);
-	sdmac->desc = NULL;
 	spin_unlock_irqrestore(&sdmac->vc.lock, flags);
 	vchan_dma_desc_free_list(&sdmac->vc, &head);
 }
@@ -1052,11 +1047,19 @@ static void sdma_channel_terminate_work(struct work_struct *work)
 static int sdma_disable_channel_async(struct dma_chan *chan)
 {
 	struct sdma_channel *sdmac = to_sdma_chan(chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&sdmac->vc.lock, flags);
 
 	sdma_disable_channel(chan);
 
-	if (sdmac->desc)
+	if (sdmac->desc) {
+		vchan_terminate_vdesc(&sdmac->desc->vd);
+		sdmac->desc = NULL;
 		schedule_work(&sdmac->terminate_worker);
+	}
+
+	spin_unlock_irqrestore(&sdmac->vc.lock, flags);
 
 	return 0;
 }
-- 
2.20.1