vfio/virtio: Use guard() for bar_mutex in legacy I/O

Convert the bar_mutex acquisition in virtiovf_issue_legacy_rw_cmd()
to use guard(), eliminating the out label and goto-based error paths
in favor of direct returns.

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/20260414200625.3601509-5-alex.williamson@nvidia.com
Signed-off-by: Alex Williamson <alex@shazbot.org>

diff --git a/drivers/vfio/pci/virtio/legacy_io.c b/drivers/vfio/pci/virtio/legacy_io.c
index 1ed349a556291b41736e0e2d0c0c7f99f30f437e..f022301e60d6e888d5cc4dcd2fad46bb81391b66 100644 (file)
--- a/drivers/vfio/pci/virtio/legacy_io.c
+++ b/drivers/vfio/pci/virtio/legacy_io.c
@@ -34,7 +34,9 @@ virtiovf_issue_legacy_rw_cmd(struct virtiovf_pci_core_device *virtvdev,
        common = pos < VIRTIO_PCI_CONFIG_OFF(msix_enabled);
        /* offset within the relevant configuration area */
        offset = common ? pos : pos - VIRTIO_PCI_CONFIG_OFF(msix_enabled);
-       mutex_lock(&virtvdev->bar_mutex);
+
+       guard(mutex)(&virtvdev->bar_mutex);
+
        if (read) {
                if (common)
                        ret = virtio_pci_admin_legacy_common_io_read(pdev, offset,
@@ -43,14 +45,12 @@ virtiovf_issue_legacy_rw_cmd(struct virtiovf_pci_core_device *virtvdev,
                        ret = virtio_pci_admin_legacy_device_io_read(pdev, offset,
                                        count, bar0_buf + pos);
                if (ret)
-                       goto out;
+                       return ret;
                if (copy_to_user(buf, bar0_buf + pos, count))
-                       ret = -EFAULT;
+                       return -EFAULT;
        } else {
-               if (copy_from_user(bar0_buf + pos, buf, count)) {
-                       ret = -EFAULT;
-                       goto out;
-               }
+               if (copy_from_user(bar0_buf + pos, buf, count))
+                       return -EFAULT;
 
                if (common)
                        ret = virtio_pci_admin_legacy_common_io_write(pdev, offset,
@@ -59,8 +59,7 @@ virtiovf_issue_legacy_rw_cmd(struct virtiovf_pci_core_device *virtvdev,
                        ret = virtio_pci_admin_legacy_device_io_write(pdev, offset,
                                        count, bar0_buf + pos);
        }
-out:
-       mutex_unlock(&virtvdev->bar_mutex);
+
        return ret;
 }