[PATCH v2 3/7] dma/idxd: replace rte atomics with GCC builtin atomics

[Tyler Retzlaff]

Replace the use of rte_atomic.h types and functions, instead use GCC
supplied C++11 memory model builtins.

Signed-off-by: Tyler Retzlaff <roret...@linux.microsoft.com>
---
 drivers/dma/idxd/idxd_internal.h | 3 +--
 drivers/dma/idxd/idxd_pci.c      | 8 +++++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/idxd/idxd_internal.h b/drivers/dma/idxd/idxd_internal.h
index 180a858..cd41777 100644
--- a/drivers/dma/idxd/idxd_internal.h
+++ b/drivers/dma/idxd/idxd_internal.h
@@ -7,7 +7,6 @@
 
 #include <rte_dmadev_pmd.h>
 #include <rte_spinlock.h>
-#include <rte_atomic.h>
 
 #include "idxd_hw_defs.h"
 
@@ -34,7 +33,7 @@ struct idxd_pci_common {
        rte_spinlock_t lk;
 
        uint8_t wq_cfg_sz;
-       rte_atomic16_t ref_count;
+       uint16_t ref_count;
        volatile struct rte_idxd_bar0 *regs;
        volatile uint32_t *wq_regs_base;
        volatile struct rte_idxd_grpcfg *grp_regs;
diff --git a/drivers/dma/idxd/idxd_pci.c b/drivers/dma/idxd/idxd_pci.c
index 781fa02..89cce1d 100644
--- a/drivers/dma/idxd/idxd_pci.c
+++ b/drivers/dma/idxd/idxd_pci.c
@@ -6,7 +6,6 @@
 #include <rte_devargs.h>
 #include <rte_dmadev_pmd.h>
 #include <rte_malloc.h>
-#include <rte_atomic.h>
 
 #include "idxd_internal.h"
 
@@ -136,7 +135,9 @@
        /* if this is the last WQ on the device, disable the device and free
         * the PCI struct
         */
-       is_last_wq = rte_atomic16_dec_and_test(&idxd->u.pci->ref_count);
+       // NOTE: review for potential ordering optimization
+       is_last_wq = __atomic_fetch_sub(&idxd->u.pci->ref_count, 1,
+               __ATOMIC_SEQ_CST) - 1 == 0;
        if (is_last_wq) {
                /* disable the device */
                err_code = idxd_pci_dev_command(idxd, idxd_disable_dev);
@@ -350,7 +351,8 @@
                                free(idxd.u.pci);
                        return ret;
                }
-               rte_atomic16_inc(&idxd.u.pci->ref_count);
+               // NOTE: review for potential ordering optimization
+               __atomic_fetch_add(&idxd.u.pci->ref_count, 1, __ATOMIC_SEQ_CST);
        }
 
        return 0;
-- 
1.8.3.1