dmatest: Fix NULL pointer dereference on ioat

device_control is an optional and not implemented in all DMA drivers.
Any calls to these will result in a NULL pointer dereference.  dmatest
makes two of these calls when completing the kernel thread and removing
the module.  These are corrected by calling the dmaengine_device_control
wrapper and checking for a non-existant device_control function pointer
there.

Signed-off-by: Jon Mason <jon.mason@intel.com>
CC: Vinod Koul <vinod.koul@intel.com>
CC: Dan Williams <djbw@fb.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>

2 files changed, 6 insertions, 3 deletions

diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index 3a8047b1f108..99a75e5d66be 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -536,7 +536,7 @@ err_srcs:
                         thread_name, total_tests, failed_tests, ret);
 
         /* terminate all transfers on specified channels */
-        chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
+        dmaengine_terminate_all(chan);
         if (iterations > 0)
                 while (!kthread_should_stop()) {
                         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wait_dmatest_exit);
@@ -561,7 +561,7 @@ static void dmatest_cleanup_channel(struct dmatest_chan *dtc)
         }
 
         /* terminate all transfers on specified channels */
-        dtc->chan->device->device_control(dtc->chan, DMA_TERMINATE_ALL, 0);
+        dmaengine_terminate_all(dtc->chan);
 
         kfree(dtc);
 }
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 3aa76dbed166..be6e95395b11 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -608,7 +608,10 @@ static inline int dmaengine_device_control(struct dma_chan *chan,
                                            enum dma_ctrl_cmd cmd,
                                            unsigned long arg)
 {
-        return chan->device->device_control(chan, cmd, arg);
+        if (chan->device->device_control)
+                return chan->device->device_control(chan, cmd, arg);
+        else
+                return -ENOSYS;
 }
 
 static inline int dmaengine_slave_config(struct dma_chan *chan,