ptrace: cleanup arch_ptrace() on x86

Remove checking @addr less than 0 because @addr is now unsigned and
use new udescp variable in order to remove unnecessary castings.

[akpm@linux-foundation.org: fix unused variable 'udescp']
Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/x86/kernel/ptrace.c

@@ -813,8 +813,7 @@ long arch_ptrace(struct task_struct *child, long request,
 		unsigned long tmp;
 
 		ret = -EIO;
-		if ((addr & (sizeof(data) - 1)) || addr < 0 ||
-		    addr >= sizeof(struct user))
+		if ((addr & (sizeof(data) - 1)) || addr >= sizeof(struct user))
 			break;
 
 		tmp = 0;  /* Default return condition */
@@ -831,8 +830,7 @@ long arch_ptrace(struct task_struct *child, long request,
 
 	case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
 		ret = -EIO;
-		if ((addr & (sizeof(data) - 1)) || addr < 0 ||
-		    addr >= sizeof(struct user))
+		if ((addr & (sizeof(data) - 1)) || addr >= sizeof(struct user))
 			break;
 
 		if (addr < sizeof(struct user_regs_struct))
@@ -892,14 +890,14 @@ long arch_ptrace(struct task_struct *child, long request,
 		if ((int) addr < 0)
 			return -EIO;
 		ret = do_get_thread_area(child, addr,
-					 (struct user_desc __user *) data);
+					(struct user_desc __user *)data);
 		break;
 
 	case PTRACE_SET_THREAD_AREA:
 		if ((int) addr < 0)
 			return -EIO;
 		ret = do_set_thread_area(child, addr,
-					 (struct user_desc __user *) data, 0);
+					(struct user_desc __user *)data, 0);
 		break;
 #endif