From 61b67684c4a4d04b30d9ed67aa2eadfa0089c590 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 13 Aug 2014 19:39:56 +0200 Subject: perf: Fix perf_poll to return proper POLLHUP value Currently perf_poll returns POLL_HUP in case of error, which is wrong, because poll syscall expects POLLHUP. The POLL_HUP is meant to be used for SIGIO state. Signed-off-by: Jiri Olsa Acked-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140811120102.GY9918@twins.programming.kicks-ass.net Cc: Adrian Hunter Cc: Arnaldo Carvalho de Melo Cc: Corey Ashford Cc: David Ahern Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Jean Pihet Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-0ywfthh4lh65swe15f6w2x2q@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index 2d7363adf678..4575dd6e59ea 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3627,7 +3627,7 @@ static unsigned int perf_poll(struct file *file, poll_table *wait) { struct perf_event *event = file->private_data; struct ring_buffer *rb; - unsigned int events = POLL_HUP; + unsigned int events = POLLHUP; poll_wait(file, &event->waitq, wait); /* -- cgit v1.2.3 From 179033b3e064d2cd3f5f9945e76b0a0f0fbf4883 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Thu, 7 Aug 2014 11:48:26 -0400 Subject: 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 Acked-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140811120102.GY9918@twins.programming.kicks-ass.net Cc: Adrian Hunter Cc: Arnaldo Carvalho de Melo Cc: Corey Ashford Cc: David Ahern Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Jean Pihet Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-t5y3w8jjx6tfo5w8y6oajsjq@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- include/linux/perf_event.h | 1 + kernel/events/core.c | 10 +++++++++- 2 files changed, 10 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index f0a1036b1911..893a0d07986f 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -269,6 +269,7 @@ struct pmu { * enum perf_event_active_state - the states of a event */ enum perf_event_active_state { + PERF_EVENT_STATE_EXIT = -3, PERF_EVENT_STATE_ERROR = -2, PERF_EVENT_STATE_OFF = -1, PERF_EVENT_STATE_INACTIVE = 0, 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); } } -- cgit v1.2.3