[PATCH v1 5/7] iommufd: Break the loop on failure in iommufd_fault_fops_read()

[Nicolin Chen]

On a copy_to_user() failure inside the inner list_for_each_entry, only the
inner loop breaks; the outer while re-fetches the just-restored fault group
and retries the failing copy_to_user() forever, spinning the reader at 100%
CPU with fault->mutex held.

Check rc after the inner loop and break the outer while as well.

Fixes: 07838f7fd529 ("iommufd: Add iommufd fault object")
Cc: sta...@vger.kernel.org
Signed-off-by: Nicolin Chen <nicol...@nvidia.com>
---
 drivers/iommu/iommufd/eventq.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iommu/iommufd/eventq.c b/drivers/iommu/iommufd/eventq.c
index 613024ca8f1ff..1c010e691f972 100644
--- a/drivers/iommu/iommufd/eventq.c
+++ b/drivers/iommu/iommufd/eventq.c
@@ -168,6 +168,8 @@ static ssize_t iommufd_fault_fops_read(struct file *filep, 
char __user *buf,
                        }
                        done += fault_size;
                }
+               if (rc)
+                       break;
        }
        mutex_unlock(&fault->mutex);
 
-- 
2.43.0