While debugging latency issues for task waiting on epoll_wait, sometimes it becomes necessary to see if the lower layer is invoking ep_poll_callback timely for a given pid or not. Recording task_struct in involved eppoll_entry's wait_queue_entry, allows us to check this using a probe (say dtrace) at this function. We could also achieve this by checking wait_queue_entry on eventpoll's wait_queue_head itself, but that would involve more indirections. Signed-off-by: Imran Khan <imran.f.khan@xxxxxxxxxx> --- Since it just helps in debugging, I have kept the patch RFC. fs/eventpoll.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 3534d36a1474..3d4faf0a2d25 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1287,6 +1287,8 @@ static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, init_waitqueue_func_entry(&pwq->wait, ep_poll_callback); pwq->whead = whead; pwq->base = epi; + pwq->wait.private = current; + if (epi->event.events & EPOLLEXCLUSIVE) add_wait_queue_exclusive(whead, &pwq->wait); else -- 2.34.1
