From 4b76112dc43b775abd3deb2d9f65458ca08424ee Mon Sep 17 00:00:00 2001 From: Florin Coras Date: Thu, 21 Mar 2019 13:54:53 -0700 Subject: session/fifo: make event unset atomic Ensures that fifo cursize loads cannot be speculated to before the event unset. Change-Id: Ia7c20c510d58f26a8e9b82d3982c6d4143a3a4d6 Signed-off-by: Florin Coras --- src/svm/svm_fifo.h | 4 ++-- src/vnet/session/application_interface.h | 10 ++++++---- 2 files changed, 8 insertions(+), 6 deletions(-) (limited to 'src') diff --git a/src/svm/svm_fifo.h b/src/svm/svm_fifo.h index d7146ae1fb0..6c3940dfad5 100644 --- a/src/svm/svm_fifo.h +++ b/src/svm/svm_fifo.h @@ -179,12 +179,12 @@ svm_fifo_set_event (svm_fifo_t * f) /** * Unsets fifo event flag. * - * Also acts as a release barrier. + * Also acts as an acquire barrier. */ always_inline void svm_fifo_unset_event (svm_fifo_t * f) { - clib_atomic_release (&f->has_event); + __atomic_exchange_n (&f->has_event, 0, __ATOMIC_ACQUIRE); } svm_fifo_t *svm_fifo_create (u32 data_size_in_bytes); diff --git a/src/vnet/session/application_interface.h b/src/vnet/session/application_interface.h index 56d034e18ed..8323e72e768 100644 --- a/src/vnet/session/application_interface.h +++ b/src/vnet/session/application_interface.h @@ -475,9 +475,10 @@ app_send_dgram_raw (svm_fifo_t * f, app_session_transport_t * at, rv = svm_fifo_enqueue_nowait (f, sizeof (hdr), (u8 *) & hdr); ASSERT (rv == sizeof (hdr)); - if ((rv = svm_fifo_enqueue_nowait (f, actual_write, data)) > 0) + rv = svm_fifo_enqueue_nowait (f, actual_write, data); + if (do_evt) { - if (do_evt && svm_fifo_set_event (f)) + if (rv > 0 && svm_fifo_set_event (f)) app_send_io_evt_to_vpp (vpp_evt_q, f->master_session_index, evt_type, noblock); } @@ -499,9 +500,10 @@ app_send_stream_raw (svm_fifo_t * f, svm_msg_q_t * vpp_evt_q, u8 * data, { int rv; - if ((rv = svm_fifo_enqueue_nowait (f, len, data)) > 0) + rv = svm_fifo_enqueue_nowait (f, len, data); + if (do_evt) { - if (do_evt && svm_fifo_set_event (f)) + if (rv > 0 && svm_fifo_set_event (f)) app_send_io_evt_to_vpp (vpp_evt_q, f->master_session_index, evt_type, noblock); } -- cgit 1.2.3-korg