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tracing: Don't use tracing_record_cmdline() in workqueue tracer fix 

commit c3ffc7a40b
"Don't use tracing_record_cmdline() in workqueue tracer"
has a race window.

find_task_by_vpid() requires task_list_lock().

LKML-Reference: <20090313090042.43CD.A69D9226@jp.fujitsu.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This commit is contained in:
KOSAKI Motohiro 2009-03-13 09:03:04 +09:00 committed by Steven Rostedt
parent 39842323ce
commit 889a6c3672
1 changed files with 13 additions and 5 deletions
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18
kernel/trace/trace_workqueue.c
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@ -193,12 +193,20 @@ static int workqueue_stat_show(struct seq_file *s, void *p)
struct cpu_workqueue_stats *cws = p;
unsigned long flags;
int cpu = cws->cpu;
struct task_struct *tsk = find_task_by_vpid(cws->pid);
struct pid *pid;
struct task_struct *tsk;
seq_printf(s, "%3d %6d %6u %s\n", cws->cpu,
atomic_read(&cws->inserted),
cws->executed,
tsk ? tsk->comm : "<...>");
pid = find_get_pid(cws->pid);
if (pid) {
tsk = get_pid_task(pid, PIDTYPE_PID);
if (tsk) {
seq_printf(s, "%3d %6d %6u %s\n", cws->cpu,
atomic_read(&cws->inserted), cws->executed,
tsk->comm);
put_task_struct(tsk);
}
put_pid(pid);
}
spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
if (&cws->list == workqueue_cpu_stat(cpu)->list.next)