From 2c1291325d9c6f5cd24c9a98b86154ade667328f Mon Sep 17 00:00:00 2001 From: Vishwanatha Subbanna Date: Tue, 29 Aug 2017 21:12:01 +0530 Subject: Seek to file offset 0 after reading error file For a fd watching for data in sysfs file, a poll would return immediately after read unless file is closed and re-opened OR stream is seeked to 0. This commit chooses latter. From stackoverflow: Once poll/select indicates that the value has changed, you need to close and re-open the file, or seek to 0 and read again. Also, use EPOLLPRI | EPOLLERR than EPOLLIN as needed by sysfs_inotify Change-Id: I243cdfd9a09c567eac5e52abd9980ebf90b94f89 Signed-off-by: Vishwanatha Subbanna --- occ_errors.cpp | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/occ_errors.cpp b/occ_errors.cpp index fe81f17..bc01c91 100644 --- a/occ_errors.cpp +++ b/occ_errors.cpp @@ -42,7 +42,7 @@ void Error::registerCallBack() { decltype(eventSource.get()) sourcePtr = nullptr; auto r = sd_event_add_io(event.get(), &sourcePtr, fd, - EPOLLIN, processEvents, this); + EPOLLPRI | EPOLLERR, processEvents, this); eventSource.reset(sourcePtr); if (r < 0) @@ -150,6 +150,19 @@ std::string Error::readFile(int len) const phosphor::logging::org::open_power::OCC::Device:: ReadFailure::CALLOUT_DEVICE_PATH(file.c_str())); } + + // Need to seek to START, else the poll returns immediately telling + // there is data to be read + r = lseek(fd, 0, SEEK_SET); + if (r < 0) + { + log("Failure seeking error file to START"); + elog( + phosphor::logging::org::open_power::OCC::Device:: + ConfigFailure::CALLOUT_ERRNO(errno), + phosphor::logging::org::open_power::OCC::Device:: + ConfigFailure::CALLOUT_DEVICE_PATH(file.c_str())); + } return std::string(data.get()); } -- cgit v1.2.1