[dpdk-stable] [PATCH RFC v1 3/7] net/ena: relax the rmb for DMA

[Gavin Hu]

The user space DPDK rte_cio_rmb barrier in definition corresponds to the
kernel dma_rmb barrier on all supported architectures[1][2][3].

As it is called in the data path[4], redefine it to relax the barrier and
uplift the performance.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/
linux.git/tree/arch/x86/include/asm/barrier.h?h=v5.5#n54
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/
linux.git/tree/arch/powerpc/include/asm/barrier.h?h=v5.5#n46
[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/
linux.git/tree/arch/arm64/include/asm/barrier.h?h=v5.5#n48
[4] http://code.dpdk.org/dpdk/v20.02/source/drivers/net/ena/
ena_ethdev.c#L2021

Fixes: b68309be44c0 ("net/ena/base: update communication layer for the ENAv2")
Cc: stable at dpdk.org

Signed-off-by: Gavin Hu <gavin.hu at arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
---
 drivers/net/ena/base/ena_plat_dpdk.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ena/base/ena_plat_dpdk.h b/drivers/net/ena/base/ena_plat_dpdk.h
index b611fb204..60327a726 100644
--- a/drivers/net/ena/base/ena_plat_dpdk.h
+++ b/drivers/net/ena/base/ena_plat_dpdk.h
@@ -254,7 +254,7 @@ extern uint32_t ena_alloc_cnt;
 #define msleep(x) rte_delay_us(x * 1000)
 #define udelay(x) rte_delay_us(x)
 
-#define dma_rmb() rmb()
+#define dma_rmb() rte_cio_rmb()
 
 #define MAX_ERRNO       4095
 #define IS_ERR(x) (((unsigned long)x) >= (unsigned long)-MAX_ERRNO)
-- 
2.17.1