[PATCH 4/4] KVM: VFIO: update coherency only if file was deleted

["Carlos López" <clopez@suse.de>]

When servicing a KVM_DEV_VFIO_FILE_DEL request, if a file is removed
from kv->file_list, kv->noncoherent needs to be updated, in case we
can revert to using coherent DMA. However, if we found no candidate
to remove, there is no need to re-scan the list, so do it only if a
matching file was found.

To simplify the control flow, use a mutex guard so that we can return
early from within the search loop if the maching file is found.

Signed-off-by: Carlos López <clopez@suse.de>
---
 virt/kvm/vfio.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index e1c88c0b82d9..47a3b8d82735 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -190,27 +190,21 @@ static int kvm_vfio_file_del(struct kvm_device *dev, unsigned int fd)
 	struct kvm_vfio *kv = dev->private;
 	struct kvm_vfio_file *kvf;
 	CLASS(fd, f)(fd);
-	int ret;
 
 	if (fd_empty(f))
 		return -EBADF;
 
-	ret = -ENOENT;
-
-	mutex_lock(&kv->lock);
+	guard(mutex)(&kv->lock);
 
 	list_for_each_entry(kvf, &kv->file_list, node) {
 		if (kvf->file == fd_file(f)) {
 			kvm_vfio_file_free(dev, kvf);
-			ret = 0;
-			break;
+			kvm_vfio_update_coherency(dev);
+			return 0;
 		}
 	}
 
-	kvm_vfio_update_coherency(dev);
-
-	mutex_unlock(&kv->lock);
-	return ret;
+	return -ENOENT;
 }
 
 #ifdef CONFIG_SPAPR_TCE_IOMMU
-- 
2.51.0