From 1d953111b648e48923171c3c9cf17be2250544fa Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 22 Aug 2017 17:59:28 +0200 Subject: [PATCH] perf/core: Don't report zero PIDs for exiting tasks 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 Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170822155928.GA6892@redhat.com Signed-off-by: Ingo Molnar --- 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 1ac5015bab04..b411321b6c26 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); } /* -- 2.20.1