x86: Use kmemdup() in copy_thread(), rather than duplicating its implementation

The semantic patch that makes this change is available
in scripts/coccinelle/api/memdup.cocci.
Signed-off-by: NThomas Meyer <thomas@m3y3r.de>
Link: http://lkml.kernel.org/r/1321569820.1624.275.camel@localhost.localdomainSigned-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/process_64.c

@@ -293,13 +293,12 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
 	memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 
 	if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
-		p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
+		p->thread.io_bitmap_ptr = kmemdup(me->thread.io_bitmap_ptr,
+						  IO_BITMAP_BYTES, GFP_KERNEL);
 		if (!p->thread.io_bitmap_ptr) {
 			p->thread.io_bitmap_max = 0;
 			return -ENOMEM;
 		}
-		memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr,
-				IO_BITMAP_BYTES);
 		set_tsk_thread_flag(p, TIF_IO_BITMAP);
 	}