[systemd-devel] [RFC 01/12] event: allow EPOLLET as event flag
EPOLLET enables edge-triggered mode (see epoll(7) for more). For most use-cases, level-triggered is just fine, but for master-TTYs we need edge-triggered to catch EPOLLHUP. master-TTYs signal EPOLLHUP if no client is connected, but a client may connect some time later (same happens during vhangup(2)). However, epoll doesn't allow masking EPOLLHUP so it's signaled constantly. To avoid this, edge-triggered mode is needed. --- src/libsystemd-bus/sd-event.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/libsystemd-bus/sd-event.c b/src/libsystemd-bus/sd-event.c index 6a6581b..b5ddf71 100644 --- a/src/libsystemd-bus/sd-event.c +++ b/src/libsystemd-bus/sd-event.c @@ -584,7 +584,7 @@ _public_ int sd_event_add_io( assert_return(e, -EINVAL); assert_return(fd = 0, -EINVAL); -assert_return(!(events ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP)), -EINVAL); +assert_return(!(events ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET)), -EINVAL); assert_return(callback, -EINVAL); assert_return(ret, -EINVAL); assert_return(e-state != SD_EVENT_FINISHED, -ESTALE); @@ -1022,7 +1022,7 @@ _public_ int sd_event_source_set_io_events(sd_event_source *s, uint32_t events) assert_return(s, -EINVAL); assert_return(s-type == SOURCE_IO, -EDOM); -assert_return(!(events ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP)), -EINVAL); +assert_return(!(events ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET)), -EINVAL); assert_return(s-event-state != SD_EVENT_FINISHED, -ESTALE); assert_return(!event_pid_changed(s-event), -ECHILD); -- 1.8.4.2 ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] [RFC 01/12] event: allow EPOLLET as event flag
On Wed, 27.11.13 19:48, David Herrmann (dh.herrm...@gmail.com) wrote: Looks obvious. Applied. EPOLLET enables edge-triggered mode (see epoll(7) for more). For most use-cases, level-triggered is just fine, but for master-TTYs we need edge-triggered to catch EPOLLHUP. master-TTYs signal EPOLLHUP if no client is connected, but a client may connect some time later (same happens during vhangup(2)). However, epoll doesn't allow masking EPOLLHUP so it's signaled constantly. To avoid this, edge-triggered mode is needed. --- src/libsystemd-bus/sd-event.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/libsystemd-bus/sd-event.c b/src/libsystemd-bus/sd-event.c index 6a6581b..b5ddf71 100644 --- a/src/libsystemd-bus/sd-event.c +++ b/src/libsystemd-bus/sd-event.c @@ -584,7 +584,7 @@ _public_ int sd_event_add_io( assert_return(e, -EINVAL); assert_return(fd = 0, -EINVAL); -assert_return(!(events ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP)), -EINVAL); +assert_return(!(events ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET)), -EINVAL); assert_return(callback, -EINVAL); assert_return(ret, -EINVAL); assert_return(e-state != SD_EVENT_FINISHED, -ESTALE); @@ -1022,7 +1022,7 @@ _public_ int sd_event_source_set_io_events(sd_event_source *s, uint32_t events) assert_return(s, -EINVAL); assert_return(s-type == SOURCE_IO, -EDOM); -assert_return(!(events ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP)), -EINVAL); +assert_return(!(events ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET)), -EINVAL); assert_return(s-event-state != SD_EVENT_FINISHED, -ESTALE); assert_return(!event_pid_changed(s-event), -ECHILD); Lennart -- Lennart Poettering, Red Hat ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
