[PATCH 1/6] Move poll into perf_event and allow for wakeups when fd has not been mmap'd. This is useful when using read() to read out the current counter value.
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From: highguy on 7 Feb 2010 06:40 From: Stijn Devriendt <stijn(a)stijn.telenet.be> --- include/linux/perf_event.h | 2 +- kernel/perf_event.c | 30 +++++++++++++++--------------- 2 files changed, 16 insertions(+), 16 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index c66b34f..827a221 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -538,7 +538,6 @@ struct perf_mmap_data { int writable; /* are we writable */ int nr_locked; /* nr pages mlocked */ - atomic_t poll; /* POLL_ for wakeups */ atomic_t events; /* event_id limit */ atomic_long_t head; /* write position */ @@ -639,6 +638,7 @@ struct perf_event { struct perf_mmap_data *data; /* poll related */ + atomic_t poll; /* POLL_ for wakeups */ wait_queue_head_t waitq; struct fasync_struct *fasync; diff --git a/kernel/perf_event.c b/kernel/perf_event.c index e0eb4a2..42dc18d 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -1919,14 +1919,7 @@ perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) static unsigned int perf_poll(struct file *file, poll_table *wait) { struct perf_event *event = file->private_data; - struct perf_mmap_data *data; - unsigned int events = POLL_HUP; - - rcu_read_lock(); - data = rcu_dereference(event->data); - if (data) - events = atomic_xchg(&data->poll, 0); - rcu_read_unlock(); + unsigned int events = atomic_xchg(&event->poll, 0); poll_wait(file, &event->waitq, wait); @@ -2680,16 +2673,20 @@ static bool perf_output_space(struct perf_mmap_data *data, unsigned long tail, return true; } -static void perf_output_wakeup(struct perf_output_handle *handle) +static void __perf_output_wakeup(struct perf_event* event, int nmi) { - atomic_set(&handle->data->poll, POLL_IN); + atomic_set(&event->poll, POLLIN); - if (handle->nmi) { - handle->event->pending_wakeup = 1; - perf_pending_queue(&handle->event->pending, - perf_pending_event); + if (nmi) { + event->pending_wakeup = 1; + perf_pending_queue(&event->pending, perf_pending_event); } else - perf_event_wakeup(handle->event); + perf_event_wakeup(event); +} + +static void perf_output_wakeup(struct perf_output_handle *handle) +{ + __perf_output_wakeup(handle->event, handle->nmi); } /* @@ -3171,6 +3168,9 @@ static void perf_event_output(struct perf_event *event, int nmi, struct perf_output_handle handle; struct perf_event_header header; + if (!event->data) + return __perf_output_wakeup(event, nmi); + perf_prepare_sample(&header, data, event, regs); if (perf_output_begin(&handle, event, header.size, nmi, 1)) -- 1.6.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |