linux-kernel - [tip:perf/core] hw_breakpoint: Simplify the "weight" usage in toggle_bp

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Message-ID: <tip-7ab71f3244e9f970c29566c5a67e13d1fa38c387@git.kernel.org>
Date:	Thu, 20 Jun 2013 09:19:04 -0700
From:	tip-bot for Oleg Nesterov <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	fweisbec@...il.com, vincent.weaver@...ne.edu, oleg@...hat.com,
	tglx@...utronix.de
Subject: [tip:perf/core] hw_breakpoint: Simplify the "weight"
  usage in toggle_bp_slot() paths

Commit-ID:  7ab71f3244e9f970c29566c5a67e13d1fa38c387
Gitweb:     http://git.kernel.org/tip/7ab71f3244e9f970c29566c5a67e13d1fa38c387
Author:     Oleg Nesterov <oleg@...hat.com>
AuthorDate: Thu, 20 Jun 2013 17:50:13 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 20 Jun 2013 17:58:55 +0200

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@...ne.edu>
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Acked-by: Frederic Weisbecker <fweisbec@...il.com>
Link: http://lkml.kernel.org/r/20130620155013.GA6337@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/events/hw_breakpoint.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index dee0148..5cd4f6d 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -182,7 +182,7 @@ 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 */
@@ -190,10 +190,7 @@ static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable,
 	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)
--
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