netdev - [PATCH net-next 1/2] r8169: improve rtl

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Message-ID: <1ede7930-0018-49dc-b63a-7c77dd4b367b@gmail.com>
Date:   Sun, 6 Dec 2020 01:00:07 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>,
        David Miller <davem@...emloft.net>,
        Realtek linux nic maintainers <nic_swsd@...ltek.com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net-next 1/2] r8169: improve rtl_rx

There's no need to check min(budget, NUM_RX_DESC). At first budget
(NAPI_POLL_WEIGHT = 64) is less then NUM_RX_DESC (256).
And more important: Even in case of budget > NUM_RX_DESC we could
safely continue processing descriptors as long as they are owned by
the CPU. In addition replace rx_left with a normal counter variable,
this allows to simplify the code. Last but not least there's no need
any longer to pass the budget as an u32.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 3ef1b31c9..3ea27a657 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4415,15 +4415,13 @@ static inline void rtl8169_rx_csum(struct sk_buff *skb, u32 opts1)
 		skb_checksum_none_assert(skb);
 }
 
-static int rtl_rx(struct net_device *dev, struct rtl8169_private *tp, u32 budget)
+static int rtl_rx(struct net_device *dev, struct rtl8169_private *tp, int budget)
 {
-	unsigned int cur_rx, rx_left, count;
 	struct device *d = tp_to_dev(tp);
+	int count;
 
-	cur_rx = tp->cur_rx;
-
-	for (rx_left = min(budget, NUM_RX_DESC); rx_left > 0; rx_left--, cur_rx++) {
-		unsigned int pkt_size, entry = cur_rx % NUM_RX_DESC;
+	for (count = 0; count < budget; count++, tp->cur_rx++) {
+		unsigned int pkt_size, entry = tp->cur_rx % NUM_RX_DESC;
 		struct RxDesc *desc = tp->RxDescArray + entry;
 		struct sk_buff *skb;
 		const void *rx_buf;
@@ -4500,9 +4498,6 @@ static int rtl_rx(struct net_device *dev, struct rtl8169_private *tp, u32 budget
 		rtl8169_mark_to_asic(desc);
 	}
 
-	count = cur_rx - tp->cur_rx;
-	tp->cur_rx = cur_rx;
-
 	return count;
 }
 
@@ -4561,7 +4556,7 @@ static int rtl8169_poll(struct napi_struct *napi, int budget)
 	struct net_device *dev = tp->dev;
 	int work_done;
 
-	work_done = rtl_rx(dev, tp, (u32) budget);
+	work_done = rtl_rx(dev, tp, budget);
 
 	rtl_tx(dev, tp, budget);
 
-- 
2.29.2