[PATCH 1/6 V2][SRU][Lunar] r8169: use spinlock to protect mac ocp register access

[Koba Ko]

From: Heiner Kallweit <hkallweit1 at gmail.com>

BugLink: https://bugs.launchpad.net/bugs/1946433                                

For disabling ASPM during NAPI poll we'll have to access mac ocp
registers in atomic context. This could result in races because
a mac ocp read consists of a write to register OCPDR, followed
by a read from the same register. Therefore add a spinlock to
protect access to mac ocp registers.

Reviewed-by: Simon Horman <simon.horman at corigine.com>
Tested-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
Tested-by: Holger Hoffstätte <holger at applied-asynchrony.com>
Signed-off-by: Heiner Kallweit <hkallweit1 at gmail.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(cherry picked from commit 91c8643578a21e435c412ffbe902bb4b4773e262)
Signed-off-by: Koba Ko <koba.ko at canonical.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 37 ++++++++++++++++++++---
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 6fd040dd74234..c3ba74c611199 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -612,6 +612,8 @@ struct rtl8169_private {
 		struct work_struct work;
 	} wk;
 
+	spinlock_t mac_ocp_lock;
+
 	unsigned supports_gmii:1;
 	unsigned aspm_manageable:1;
 	dma_addr_t counters_phys_addr;
@@ -846,7 +848,7 @@ static int r8168_phy_ocp_read(struct rtl8169_private *tp, u32 reg)
 		(RTL_R32(tp, GPHY_OCP) & 0xffff) : -ETIMEDOUT;
 }
 
-static void r8168_mac_ocp_write(struct rtl8169_private *tp, u32 reg, u32 data)
+static void __r8168_mac_ocp_write(struct rtl8169_private *tp, u32 reg, u32 data)
 {
 	if (rtl_ocp_reg_failure(reg))
 		return;
@@ -854,7 +856,16 @@ static void r8168_mac_ocp_write(struct rtl8169_private *tp, u32 reg, u32 data)
 	RTL_W32(tp, OCPDR, OCPAR_FLAG | (reg << 15) | data);
 }
 
-static u16 r8168_mac_ocp_read(struct rtl8169_private *tp, u32 reg)
+static void r8168_mac_ocp_write(struct rtl8169_private *tp, u32 reg, u32 data)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&tp->mac_ocp_lock, flags);
+	__r8168_mac_ocp_write(tp, reg, data);
+	spin_unlock_irqrestore(&tp->mac_ocp_lock, flags);
+}
+
+static u16 __r8168_mac_ocp_read(struct rtl8169_private *tp, u32 reg)
 {
 	if (rtl_ocp_reg_failure(reg))
 		return 0;
@@ -864,12 +875,28 @@ static u16 r8168_mac_ocp_read(struct rtl8169_private *tp, u32 reg)
 	return RTL_R32(tp, OCPDR);
 }
 
+static u16 r8168_mac_ocp_read(struct rtl8169_private *tp, u32 reg)
+{
+	unsigned long flags;
+	u16 val;
+
+	spin_lock_irqsave(&tp->mac_ocp_lock, flags);
+	val = __r8168_mac_ocp_read(tp, reg);
+	spin_unlock_irqrestore(&tp->mac_ocp_lock, flags);
+
+	return val;
+}
+
 static void r8168_mac_ocp_modify(struct rtl8169_private *tp, u32 reg, u16 mask,
 				 u16 set)
 {
-	u16 data = r8168_mac_ocp_read(tp, reg);
+	unsigned long flags;
+	u16 data;
 
-	r8168_mac_ocp_write(tp, reg, (data & ~mask) | set);
+	spin_lock_irqsave(&tp->mac_ocp_lock, flags);
+	data = __r8168_mac_ocp_read(tp, reg);
+	__r8168_mac_ocp_write(tp, reg, (data & ~mask) | set);
+	spin_unlock_irqrestore(&tp->mac_ocp_lock, flags);
 }
 
 /* Work around a hw issue with RTL8168g PHY, the quirk disables
@@ -5155,6 +5182,8 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	tp->eee_adv = -1;
 	tp->ocp_base = OCP_STD_PHY_BASE;
 
+	spin_lock_init(&tp->mac_ocp_lock);
+
 	dev->tstats = devm_netdev_alloc_pcpu_stats(&pdev->dev,
 						   struct pcpu_sw_netstats);
 	if (!dev->tstats)
-- 
2.25.1