tty/vt: consolemap: extract dict unsharing to con_unshare_unimap()

The code in con_set_unimap() is too nested. Extract its obvious part
into a separate function and name it after what the code does:
con_unshare_unimap().
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220607104946.18710-19-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/vt/consolemap.c

@@ -563,49 +563,28 @@ int con_clear_unimap(struct vc_data *vc)
 	return ret;
 }
 
-int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
+static struct uni_pagedict *con_unshare_unimap(struct vc_data *vc,
+		struct uni_pagedict *p)
 {
-	int err = 0, err1, i;
-	struct uni_pagedict *p, *q;
-	struct unipair *unilist, *plist;
-
-	if (!ct)
-		return 0;
-
-	unilist = vmemdup_user(list, array_size(sizeof(*unilist), ct));
-	if (IS_ERR(unilist))
-		return PTR_ERR(unilist);
-
-	console_lock();
-
-	/* Save original vc_unipagdir_loc in case we allocate a new one */
-	p = *vc->vc_uni_pagedir_loc;
-	if (!p) {
-		err = -EINVAL;
-		goto out_unlock;
-	}
-
-	if (p->refcount > 1) {
-		int j, k;
+	struct uni_pagedict *q;
 	u16 **p1, *p2, l;
+	int ret;
+	int i, j, k;
 
-		err1 = con_do_clear_unimap(vc);
-		if (err1) {
-			err = err1;
-			goto out_unlock;
-		}
+	ret = con_do_clear_unimap(vc);
+	if (ret)
+		return ERR_PTR(ret);
 
 	/*
-		 * Since refcount was > 1, con_clear_unimap() allocated a
-		 * a new uni_pagedict for this vc.  Re: p != q
+	 * Since refcount was > 1, con_clear_unimap() allocated a new
+	 * uni_pagedict for this vc.  Re: p != q
 	 */
 	q = *vc->vc_uni_pagedir_loc;
 
 	/*
-		 * uni_pgdir is a 32*32*64 table with rows allocated
-		 * when its first entry is added.  The unicode value must
-		 * still be incremented for empty rows.  We are copying
-		 * entries from "p" (old) to "q" (new).
+	 * uni_pgdir is a 32*32*64 table with rows allocated when its first
+	 * entry is added. The unicode value must still be incremented for
+	 * empty rows. We are copying entries from "p" (old) to "q" (new).
 	 */
 	l = 0;		/* unicode value */
 	for (i = 0; i < UNI_DIRS; i++) {
@@ -619,9 +598,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
 		for (j = 0; j < UNI_DIR_ROWS; j++) {
 			p2 = p1[j];
 			if (!p2) {
-					/*
-					 * Account for row of 64 empty entries
-					 */
+				/* Account for row of 64 empty entries */
 				l += UNI_ROW_GLYPHS;
 				continue;
 			}
@@ -630,26 +607,52 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
 				if (p2[k] == 0xffff)
 					continue;
 				/*
-					 * Found one, copy entry for unicode
-					 * l with fontpos value p2[k].
+				 * Found one, copy entry for unicode l with
+				 * fontpos value p2[k].
 				 */
-					err1 = con_insert_unipair(q, l, p2[k]);
-					if (err1) {
+				ret = con_insert_unipair(q, l, p2[k]);
+				if (ret) {
 					p->refcount++;
 					*vc->vc_uni_pagedir_loc = p;
 					con_release_unimap(q);
 					kfree(q);
-						err = err1;
-						goto out_unlock;
+					return ERR_PTR(ret);
 				}
 			}
 		}
 	}
 
-		/*
-		 * Finished copying font table, set vc_uni_pagedir to new table
-		 */
-		p = q;
+	return q;
+}
+
+int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
+{
+	int err = 0, err1;
+	struct uni_pagedict *p;
+	struct unipair *unilist, *plist;
+
+	if (!ct)
+		return 0;
+
+	unilist = vmemdup_user(list, array_size(sizeof(*unilist), ct));
+	if (IS_ERR(unilist))
+		return PTR_ERR(unilist);
+
+	console_lock();
+
+	/* Save original vc_unipagdir_loc in case we allocate a new one */
+	p = *vc->vc_uni_pagedir_loc;
+	if (!p) {
+		err = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (p->refcount > 1) {
+		p = con_unshare_unimap(vc, p);
+		if (IS_ERR(p)) {
+			err = PTR_ERR(p);
+			goto out_unlock;
+		}
 	} else if (p == dflt) {
 		dflt = NULL;
 	}