vfio/virtio: Use guard() for migf->lock where applicable

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.williamson@nvidia.com>
Reviewed-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20260414200625.3601509-4-alex.williamson@nvidia.com
Signed-off-by: Alex Williamson <alex@shazbot.org>

diff --git a/drivers/vfio/pci/virtio/migrate.c b/drivers/vfio/pci/virtio/migrate.c
index 601ef4865ed41b21e818d20f2066939d8cd0ee28..4b1e5502f0a71683700b8d8a335f8948f7497b11 100644 (file)
--- 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;
 }