hw_breakpoint: Simplify the "weight" usage in toggle_bp_slot() paths

Change toggle_bp_slot() to make "weight" negative if !enable.
This way we can always use "+ weight" without additional "if
(enable)" check and toggle_bp_task_slot() no longer needs this
arg.

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20130620155013.GA6337@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/events/hw_breakpoint.c

@@ -182,18 +182,15 @@ fetch_this_slot(struct bp_busy_slots *slots, int weight)
 /*
  * Add a pinned breakpoint for the given task in our constraint table
  */
-static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable,
+static void toggle_bp_task_slot(struct perf_event *bp, int cpu,
 				enum bp_type_idx type, int weight)
 {
 	/* tsk_pinned[n-1] is the number of tasks having n>0 breakpoints */
 	unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
 	int old_idx, new_idx;
 
 	old_idx = task_bp_pinned(cpu, bp, type) - 1;
-	if (enable)
-		new_idx = old_idx + weight;
-	else
-		new_idx = old_idx - weight;
+	new_idx = old_idx + weight;
 
 	if (old_idx >= 0)
 		tsk_pinned[old_idx]--;
@@ -211,22 +208,21 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
 	int cpu = bp->cpu;
 	struct task_struct *tsk = bp->hw.bp_target;
 
+	if (!enable)
+		weight = -weight;
+
 	/* Pinned counter cpu profiling */
 	if (!tsk) {
-
-		if (enable)
-			per_cpu(nr_cpu_bp_pinned[type], bp->cpu) += weight;
-		else
-			per_cpu(nr_cpu_bp_pinned[type], bp->cpu) -= weight;
+		per_cpu(nr_cpu_bp_pinned[type], cpu) += weight;
 		return;
 	}
 
 	/* Pinned counter task profiling */
 	if (cpu >= 0) {
-		toggle_bp_task_slot(bp, cpu, enable, type, weight);
+		toggle_bp_task_slot(bp, cpu, type, weight);
 	} else {
 		for_each_possible_cpu(cpu)
-			toggle_bp_task_slot(bp, cpu, enable, type, weight);
+			toggle_bp_task_slot(bp, cpu, type, weight);
 	}
 
 	if (enable)