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Subject[tip:tracing/ftrace] tracing: Don't assume possible cpu list have continuous numbers
Commit-ID:  bbcd3063597a3824357cd83c501c2a2aa21ef37b
Gitweb: http://git.kernel.org/tip/bbcd3063597a3824357cd83c501c2a2aa21ef37b
Author: "KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>
AuthorDate: Tue, 10 Mar 2009 10:49:53 +0900
Commit: Ingo Molnar <mingo@elte.hu>
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@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20090310104437.A480.A69D9226@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
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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