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

[Tyler Retzlaff <roretzla@linux.microsoft.com>]

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

Signed-off-by: Tyler Retzlaff <roretzla@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