From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho <acme@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] perf_event_pid: don't report zero pids for exiting tasks
Date: Tue, 22 Aug 2017 17:59:28 +0200 [thread overview]
Message-ID: <20170822155928.GA6892@redhat.com> (raw)
The exiting/dead task has no pids and in this case perf_event_pid/tid
return zero, change them to return -1 to distinguish this case from
idle threads.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/events/core.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 426c2ff..8c597d4 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1249,26 +1249,31 @@ unclone_ctx(struct perf_event_context *ctx)
return parent_ctx;
}
-static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
+static u32 perf_event_pid_type(struct perf_event *event, struct task_struct *p,
+ enum pid_type type)
{
+ u32 nr;
/*
* only top level events have the pid namespace they were created in
*/
if (event->parent)
event = event->parent;
- return task_tgid_nr_ns(p, event->ns);
+ nr = __task_pid_nr_ns(p, type, event->ns);
+ /* avoid -1 if it is idle thread or runs in another ns */
+ if (!nr && !pid_alive(p))
+ nr = -1;
+ return nr;
}
-static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
+static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
{
- /*
- * only top level events have the pid namespace they were created in
- */
- if (event->parent)
- event = event->parent;
+ return perf_event_pid_type(event, p, __PIDTYPE_TGID);
+}
- return task_pid_nr_ns(p, event->ns);
+static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
+{
+ return perf_event_pid_type(event, p, PIDTYPE_PID);
}
/*
--
2.5.0
next reply other threads:[~2017-08-22 15:59 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-22 15:59 Oleg Nesterov [this message]
2017-08-25 11:53 ` [tip:perf/core] perf/core: Don't report zero PIDs for exiting tasks tip-bot for Oleg Nesterov
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