From: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Date: Thu, 11 Oct 2018 15:28:26 +0300
Subject: net: socionext: clear rx irq correctly
Git-commit: 2a1e89df785082a0fd7264ca6d3d834abe84fa25
Patch-mainline: v4.19-rc8
References: bsc#1132778
commit 63ae7949e94a ("net: socionext: Use descriptor info instead of MMIO reads on Rx")
removed constant mmio reads from the driver and started using a descriptor
field to check if packet should be processed.
This lead the napi rx handler being constantly called while no packets
needed processing and ksoftirq getting 100% cpu usage. Issue one mmio read
to clear the irq correcty after processing packets
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reported-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
drivers/net/ethernet/socionext/netsec.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c
index 7aa5ebb6766c..4289ccb26e4e 100644
--- a/drivers/net/ethernet/socionext/netsec.c
+++ b/drivers/net/ethernet/socionext/netsec.c
@@ -735,8 +735,11 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget)
u16 idx = dring->tail;
struct netsec_de *de = dring->vaddr + (DESC_SZ * idx);
- if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD))
+ if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD)) {
+ /* reading the register clears the irq */
+ netsec_read(priv, NETSEC_REG_NRM_RX_PKTCNT);
break;
+ }
/* This barrier is needed to keep us from reading
* any other fields out of the netsec_de until we have
--
2.11.0