lib/stackdepot: simplify __stack_depot_save

The retval local variable in __stack_depot_save has the union type
handle_parts, but the function never uses anything but the union's handle
field.

Define retval simply as depot_stack_handle_t to simplify the code.

Link: https://lkml.kernel.org/r/3b0763c8057a1cf2f200ff250a5f9580ee36a28c.1700502145.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/stackdepot.c

@@ -366,7 +366,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *entries,
 					gfp_t alloc_flags, bool can_alloc)
 {
 	struct stack_record *found = NULL, **bucket;
-	union handle_parts retval = { .handle = 0 };
+	depot_stack_handle_t handle = 0;
 	struct page *page = NULL;
 	void *prealloc = NULL;
 	unsigned long flags;
@@ -383,7 +383,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *entries,
 	nr_entries = filter_irq_stacks(entries, nr_entries);
 
 	if (unlikely(nr_entries == 0) || stack_depot_disabled)
-		goto fast_exit;
+		return 0;
 
 	hash = hash_stack(entries, nr_entries);
 	bucket = &stack_table[hash & stack_hash_mask];
@@ -449,9 +449,8 @@ depot_stack_handle_t __stack_depot_save(unsigned long *entries,
 		free_pages((unsigned long)prealloc, DEPOT_POOL_ORDER);
 	}
 	if (found)
-		retval.handle = found->handle.handle;
-fast_exit:
-	return retval.handle;
+		handle = found->handle.handle;
+	return handle;
 }
 EXPORT_SYMBOL_GPL(__stack_depot_save);