hw-breakpoints: Simplify error handling in breakpoint creation requests

This simplifies the error handling when we create a breakpoint.
We don't need to check the NULL return value corner case anymore
since we have improved perf_event_create_kernel_counter() to
always return an error code in the failure case.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1259210142-5714-3-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/ptrace.c

@@ -657,10 +657,7 @@ restore:
 					       tsk, true);
 		thread->ptrace_bps[i] = NULL;
 
-		if (!bp) { /* incorrect bp, or we have a bug in bp API */
-			rc = -EINVAL;
-			break;
-		}
+		/* Incorrect bp, or we have a bug in bp API */
 		if (IS_ERR(bp)) {
 			rc = PTR_ERR(bp);
 			bp = NULL;
@@ -729,9 +726,6 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
 					       tsk,
 					       bp->attr.disabled);
 	}
-
-	if (!bp)
-		return -EIO;
 	/*
 	 * CHECKME: the previous code returned -EIO if the addr wasn't a
 	 * valid task virtual addr. The new one will return -EINVAL in this