iommu/amd: Fix amd_iommu_free_device()

put_device_state_wait() doesn't loop on the condition and a spurious
wakeup will have it free the device state even though there might still
be references out to it.

Fix this by using 'normal' wait primitives.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index 90f70d0e114192a43d7cd7bac3119b0fc66b185c..b6398d7285f707ca67214b56e4db727d0bcd0926 100644 (file)
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -151,18 +151,6 @@ static void put_device_state(struct device_state *dev_state)
                wake_up(&dev_state->wq);
 }
 
-static void put_device_state_wait(struct device_state *dev_state)
-{
-       DEFINE_WAIT(wait);
-
-       prepare_to_wait(&dev_state->wq, &wait, TASK_UNINTERRUPTIBLE);
-       if (!atomic_dec_and_test(&dev_state->count))
-               schedule();
-       finish_wait(&dev_state->wq, &wait);
-
-       free_device_state(dev_state);
-}
-
 /* Must be called under dev_state->lock */
 static struct pasid_state **__get_pasid_state_ptr(struct device_state *dev_state,
                                                  int pasid, bool alloc)
@@ -851,7 +839,13 @@ void amd_iommu_free_device(struct pci_dev *pdev)
        /* Get rid of any remaining pasid states */
        free_pasid_states(dev_state);
 
-       put_device_state_wait(dev_state);
+       put_device_state(dev_state);
+       /*
+        * Wait until the last reference is dropped before freeing
+        * the device state.
+        */
+       wait_event(dev_state->wq, !atomic_read(&dev_state->count));
+       free_device_state(dev_state);
 }
 EXPORT_SYMBOL(amd_iommu_free_device);