[PATCH 3/4] vfio/virtio: Use guard() for migf->lock where applicable

[Alex Williamson]

Convert migf->lock acquisitions in virtiovf_disable_fd() and
virtiovf_save_read() to use guard().  In virtiovf_save_read() this
eliminates the out_unlock label and multiple goto paths by allowing
direct returns, and removes the need for the done variable to double
as an error carrier.

Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Alex Williamson <alex.william...@nvidia.com>
---
 drivers/vfio/pci/virtio/migrate.c | 40 +++++++++++--------------------
 1 file changed, 14 insertions(+), 26 deletions(-)

diff --git a/drivers/vfio/pci/virtio/migrate.c 
b/drivers/vfio/pci/virtio/migrate.c
index 058d359c9b5a..80ca8a1b625a 100644
--- a/drivers/vfio/pci/virtio/migrate.c
+++ b/drivers/vfio/pci/virtio/migrate.c
@@ -224,10 +224,9 @@ static void virtiovf_clean_migf_resources(struct 
virtiovf_migration_file *migf)
 
 static void virtiovf_disable_fd(struct virtiovf_migration_file *migf)
 {
-       mutex_lock(&migf->lock);
+       guard(mutex)(&migf->lock);
        migf->state = VIRTIOVF_MIGF_STATE_ERROR;
        migf->filp->f_pos = 0;
-       mutex_unlock(&migf->lock);
 }
 
 static void virtiovf_disable_fds(struct virtiovf_pci_core_device *virtvdev)
@@ -385,11 +384,10 @@ static ssize_t virtiovf_save_read(struct file *filp, char 
__user *buf, size_t le
                return -ESPIPE;
        pos = &filp->f_pos;
 
-       mutex_lock(&migf->lock);
-       if (migf->state == VIRTIOVF_MIGF_STATE_ERROR) {
-               done = -ENODEV;
-               goto out_unlock;
-       }
+       guard(mutex)(&migf->lock);
+
+       if (migf->state == VIRTIOVF_MIGF_STATE_ERROR)
+               return -ENODEV;
 
        while (len) {
                ssize_t count;
@@ -398,34 +396,24 @@ static ssize_t virtiovf_save_read(struct file *filp, char 
__user *buf, size_t le
                if (first_loop_call) {
                        first_loop_call = false;
                        /* Temporary end of file as part of PRE_COPY */
-                       if (end_of_data && migf->state == 
VIRTIOVF_MIGF_STATE_PRECOPY) {
-                               done = -ENOMSG;
-                               goto out_unlock;
-                       }
-                       if (end_of_data && migf->state != 
VIRTIOVF_MIGF_STATE_COMPLETE) {
-                               done = -EINVAL;
-                               goto out_unlock;
-                       }
+                       if (end_of_data && migf->state == 
VIRTIOVF_MIGF_STATE_PRECOPY)
+                               return -ENOMSG;
+                       if (end_of_data && migf->state != 
VIRTIOVF_MIGF_STATE_COMPLETE)
+                               return -EINVAL;
                }
 
                if (end_of_data)
-                       goto out_unlock;
+                       return done;
 
-               if (!vhca_buf) {
-                       done = -EINVAL;
-                       goto out_unlock;
-               }
+               if (!vhca_buf)
+                       return -EINVAL;
 
                count = virtiovf_buf_read(vhca_buf, &buf, &len, pos);
-               if (count < 0) {
-                       done = count;
-                       goto out_unlock;
-               }
+               if (count < 0)
+                       return count;
                done += count;
        }
 
-out_unlock:
-       mutex_unlock(&migf->lock);
        return done;
 }
 
-- 
2.51.0