[PATCH v3 3/7] dma/idxd: replace rte atomics with GCC builtin atomics

[David Marchand]

Hello Bruce, Kevin,

Review please.


On Thu, Mar 23, 2023 at 11:54 PM Tyler Retzlaff
<roretzla at linux.microsoft.com> wrote:
>
> 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 at 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..2de5d15 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
>

-- 
David Marchand