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authorJiri Olsa <jolsa@kernel.org>2014-08-07 11:48:26 -0400
committerArnaldo Carvalho de Melo <acme@redhat.com>2014-08-24 08:11:09 -0300
commit179033b3e064d2cd3f5f9945e76b0a0f0fbf4883 (patch)
tree7a470e9a799e4221fd4f319f4e190fd6e313e908 /kernel/events
parent61b67684c4a4d04b30d9ed67aa2eadfa0089c590 (diff)
downloadlinux-179033b3e064d2cd3f5f9945e76b0a0f0fbf4883.tar.bz2
perf: Add PERF_EVENT_STATE_EXIT state for events with exited task
Adding new perf event state to indicate that the monitored task has exited. In this case the event stays alive until the owner task exits or close the event fd while providing the last data through the read syscall and ring buffer. Instead it needs to propagate the error info (monitored task has died) via poll and read syscalls by returning POLLHUP and 0 respectively. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140811120102.GY9918@twins.programming.kicks-ass.net Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jean Pihet <jean.pihet@linaro.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-t5y3w8jjx6tfo5w8y6oajsjq@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4575dd6e59ea..d8cb4d21a346 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3600,7 +3600,8 @@ perf_read_hw(struct perf_event *event, char __user *buf, size_t count)
* error state (i.e. because it was pinned but it couldn't be
* scheduled on to the CPU at some point).
*/
- if (event->state == PERF_EVENT_STATE_ERROR)
+ if ((event->state == PERF_EVENT_STATE_ERROR) ||
+ (event->state == PERF_EVENT_STATE_EXIT))
return 0;
if (count < event->read_size)
@@ -3630,6 +3631,10 @@ static unsigned int perf_poll(struct file *file, poll_table *wait)
unsigned int events = POLLHUP;
poll_wait(file, &event->waitq, wait);
+
+ if (event->state == PERF_EVENT_STATE_EXIT)
+ return events;
+
/*
* Pin the event->rb by taking event->mmap_mutex; otherwise
* perf_event_set_output() can swizzle our rb and make us miss wakeups.
@@ -7588,6 +7593,9 @@ __perf_event_exit_task(struct perf_event *child_event,
if (child_event->parent) {
sync_child_event(child_event, child);
free_event(child_event);
+ } else {
+ child_event->state = PERF_EVENT_STATE_EXIT;
+ perf_event_wakeup(child_event);
}
}