net: core: Use the bitmap API to allocate bitmaps

Use bitmap_zalloc() and bitmap_free() instead of hand-writing them.
It is less verbose and it improves the type checking and semantic.

While at it, add missing header inclusion (should be bitops.h,
but with the above change it becomes bitmap.h).

Suggested-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230911154534.4174265-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: andy-shev

net/core/dev.c

@@ -69,7 +69,7 @@
  */
 
 #include <linux/uaccess.h>
-#include <linux/bitops.h>
+#include <linux/bitmap.h>
 #include <linux/capability.h>
 #include <linux/cpu.h>
 #include <linux/types.h>
@@ -1080,7 +1080,7 @@ static int __dev_alloc_name(struct net *net, const char *name, char *buf)
 			return -EINVAL;
 
 		/* Use one page as a bit array of possible slots */
-		inuse = (unsigned long *) get_zeroed_page(GFP_ATOMIC);
+		inuse = bitmap_zalloc(max_netdevices, GFP_ATOMIC);
 		if (!inuse)
 			return -ENOMEM;
 
@@ -1109,7 +1109,7 @@ static int __dev_alloc_name(struct net *net, const char *name, char *buf)
 		}
 
 		i = find_first_zero_bit(inuse, max_netdevices);
-		free_page((unsigned long) inuse);
+		bitmap_free(inuse);
 	}
 
 	snprintf(buf, IFNAMSIZ, name, i);