powerpc: powernv: ocxl: use lock guard for mutex

use guard(mutex) for scope based resource management of mutex.
This would make the code simpler and easier to maintain.

More details on lock guards can be found at
https://lore.kernel.org/all/[email protected]/T/#u

Reviewed-by: Srikar Dronamraju <[email protected]>
Acked-by: Andrew Donnellan <[email protected]>
Signed-off-by: Shrikanth Hegde <[email protected]>
Tested-by: Venkat Rao Bagalkote <[email protected]>
Signed-off-by: Madhavan Srinivasan <[email protected]>
Link: https://patch.msgid.link/[email protected]

Author: Shrikanth Hegde

arch/powerpc/platforms/powernv/ocxl.c

@@ -172,12 +172,11 @@ static void pnv_ocxl_fixup_actag(struct pci_dev *dev)
 	if (phb->type != PNV_PHB_NPU_OCAPI)
 		return;
 
-	mutex_lock(&links_list_lock);
+	guard(mutex)(&links_list_lock);
 
 	link = find_link(dev);
 	if (!link) {
 		dev_warn(&dev->dev, "couldn't update actag information\n");
-		mutex_unlock(&links_list_lock);
 		return;
 	}
 
@@ -206,7 +205,6 @@ static void pnv_ocxl_fixup_actag(struct pci_dev *dev)
 	dev_dbg(&dev->dev, "total actags for function: %d\n",
 		link->fn_desired_actags[PCI_FUNC(dev->devfn)]);
 
-	mutex_unlock(&links_list_lock);
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID, pnv_ocxl_fixup_actag);
 
@@ -253,12 +251,11 @@ int pnv_ocxl_get_actag(struct pci_dev *dev, u16 *base, u16 *enabled,
 {
 	struct npu_link *link;
 
-	mutex_lock(&links_list_lock);
+	guard(mutex)(&links_list_lock);
 
 	link = find_link(dev);
 	if (!link) {
 		dev_err(&dev->dev, "actag information not found\n");
-		mutex_unlock(&links_list_lock);
 		return -ENODEV;
 	}
 	/*
@@ -274,7 +271,6 @@ int pnv_ocxl_get_actag(struct pci_dev *dev, u16 *base, u16 *enabled,
 	*enabled   = link->fn_actags[PCI_FUNC(dev->devfn)].count;
 	*supported = link->fn_desired_actags[PCI_FUNC(dev->devfn)];
 
-	mutex_unlock(&links_list_lock);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pnv_ocxl_get_actag);
@@ -293,12 +289,11 @@ int pnv_ocxl_get_pasid_count(struct pci_dev *dev, int *count)
 	 *
 	 * We only support one AFU-carrying function for now.
 	 */
-	mutex_lock(&links_list_lock);
+	guard(mutex)(&links_list_lock);
 
 	link = find_link(dev);
 	if (!link) {
 		dev_err(&dev->dev, "actag information not found\n");
-		mutex_unlock(&links_list_lock);
 		return -ENODEV;
 	}
 
@@ -309,7 +304,6 @@ int pnv_ocxl_get_pasid_count(struct pci_dev *dev, int *count)
 			break;
 		}
 
-	mutex_unlock(&links_list_lock);
 	dev_dbg(&dev->dev, "%d PASIDs available for function\n",
 		rc ? 0 : *count);
 	return rc;