[tip:tracing/ftrace] tracing: Don't assume possible cpu list have continuous numbers

[KOSAKI Motohiro]

Commit-ID:  bbcd3063597a3824357cd83c501c2a2aa21ef37b
Gitweb:     http://git.kernel.org/tip/bbcd3063597a3824357cd83c501c2a2aa21ef37b
Author:     "KOSAKI Motohiro" <kosaki.motohiro@xxxxxxxxxxxxxx>
AuthorDate: Tue, 10 Mar 2009 10:49:53 +0900
Commit:     Ingo Molnar <mingo@xxxxxxx>
CommitDate: Tue, 10 Mar 2009 10:20:30 +0100

tracing: Don't assume possible cpu list have continuous numbers

"for (++cpu ; cpu < num_possible_cpus(); cpu++)" statement assumes
possible cpus have continuous number - but that's a wrong assumption.

Insted, cpumask_next() should be used.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Cc: Steven Rostedt <srostedt@xxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
LKML-Reference: <20090310104437.A480.A69D9226@xxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 kernel/trace/trace_workqueue.c |   14 +++++++-------
 1 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/trace_workqueue.c b/kernel/trace/trace_workqueue.c
index 46c8dc8..739fdac 100644
--- a/kernel/trace/trace_workqueue.c
+++ b/kernel/trace/trace_workqueue.c
@@ -91,7 +91,7 @@ static void probe_workqueue_creation(struct task_struct *wq_thread, int cpu)
 	struct cpu_workqueue_stats *cws;
 	unsigned long flags;
 
-	WARN_ON(cpu < 0 || cpu >= num_possible_cpus());
+	WARN_ON(cpu < 0);
 
 	/* Workqueues are sometimes created in atomic context */
 	cws = kzalloc(sizeof(struct cpu_workqueue_stats), GFP_ATOMIC);
@@ -175,12 +175,12 @@ static void *workqueue_stat_next(void *prev, int idx)
 	spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
 	if (list_is_last(&prev_cws->list, &workqueue_cpu_stat(cpu)->list)) {
 		spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
-		for (++cpu ; cpu < num_possible_cpus(); cpu++) {
-			ret = workqueue_stat_start_cpu(cpu);
-			if (ret)
-				return ret;
-		}
-		return NULL;
+		do {
+			cpu = cpumask_next(cpu, cpu_possible_mask);
+			if (cpu >= nr_cpu_ids)
+				return NULL;
+		} while (!(ret = workqueue_stat_start_cpu(cpu)));
+		return ret;
 	}
 	spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
 
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