A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-29 03:01:39 -04:00
Code Issues Projects Releases Packages Wiki Activity

dmaengine: Store module owner in dma_device struct

Browse source 
[ 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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
This commit is contained in:
Logan Gunthorpe 2019-12-16 12:01:16 -07:00 • committed by Greg Kroah-Hartman
commit f99958a96c
2 changed files with 5 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

4
drivers/dma/dmaengine.c
View file

@ -179,7 +179,7 @@ __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;
}
/**
@ -919,6 +919,8 @@ 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",