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Reinette Chatre 6744a030d8 dmaengine: idxd: Do not call DMX TX callbacks during workqueue disable

On driver unload any pending descriptors are flushed and pending
DMA descriptors are explicitly completed:
idxd_dmaengine_drv_remove() ->
	drv_disable_wq() ->
		idxd_wq_free_irq() ->
			idxd_flush_pending_descs() ->
				idxd_dma_complete_txd()

With this done during driver unload any remaining descriptor is
likely stuck and can be dropped. Even so, the descriptor may still
have a callback set that could no longer be accessible. An
example of such a problem is when the dmatest fails and the dmatest
module is unloaded. The failure of dmatest leaves descriptors with
dma_async_tx_descriptor::callback pointing to code that no longer
exist. This causes a page fault as below at the time the IDXD driver
is unloaded when it attempts to run the callback:
 BUG: unable to handle page fault for address: ffffffffc0665190
 #PF: supervisor instruction fetch in kernel mode
 #PF: error_code(0x0010) - not-present page

Fix this by clearing the callback pointers on the transmit
descriptors only when workqueue is disabled.

Fixes: 403a2e236538 ("dmaengine: idxd: change MSIX allocation based on per wq activation")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/37d06b772aa7f8863ca50f90930ea2fd80b38fc3.1670452419.git.reinette.chatre@intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

2022-12-28 16:24:50 +05:30

bus.c

Bus: Make remove callback return void tag

2021-07-27 19:12:14 +05:30

cdev.c

Merge tag 'v6.1-rc7' into iommufd.git for-next

2022-12-02 12:04:39 -04:00

compat.c

dmaengine: idxd: Fix a possible NULL pointer dereference

2021-08-02 12:35:10 +05:30

device.c

dmaengine: idxd: Do not call DMX TX callbacks during workqueue disable