Most architectures currently check this in their get_wchan() implementation
(ARC doesn't hence this patch). However doing this in core code shows
the semantics better so move the check one level up (eventually remove
the boiler-plate code from arches)

Signed-off-by: Vineet Gupta <vgu...@synopsys.com>

 #      tools/perf/arch/arc/util/
---
 fs/proc/array.c | 4 +++-
 fs/proc/base.c  | 6 ++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 65ec2029fa80..081fade5a361 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -519,8 +519,10 @@ static int do_task_stat(struct seq_file *m, struct 
pid_namespace *ns,
                unlock_task_sighand(task, &flags);
        }
 
-       if (permitted && (!whole || num_threads < 2))
+       if (task != current && task->state != TASK_RUNNING &&
+           permitted && (!whole || num_threads < 2))
                wchan = get_wchan(task);
+
        if (!whole) {
                min_flt = task->min_flt;
                maj_flt = task->maj_flt;
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 0f707003dda5..abd7ec6324c5 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -385,13 +385,15 @@ static const struct file_operations proc_pid_cmdline_ops 
= {
 static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
                          struct pid *pid, struct task_struct *task)
 {
-       unsigned long wchan;
+       unsigned long wchan = 0;
        char symname[KSYM_NAME_LEN];
 
        if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
                goto print0;
 
-       wchan = get_wchan(task);
+       if (task != current && task->state != TASK_RUNNING)
+               wchan = get_wchan(task);
+
        if (wchan && !lookup_symbol_name(wchan, symname)) {
                seq_puts(m, symname);
                return 0;
-- 
2.25.1


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