netdev - [PATCH net-next v9 4/5] r8169: Use spinlock to guard config register locking

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Message-Id: <20230225034635.2220386-5-kai.heng.feng@canonical.com>
Date:   Sat, 25 Feb 2023 11:46:34 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     hkallweit1@...il.com, nic_swsd@...ltek.com, bhelgaas@...gle.com
Cc:     koba.ko@...onical.com, acelan.kao@...onical.com,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, sathyanarayanan.kuppuswamy@...ux.intel.com,
        vidyas@...dia.com, rafael.j.wysocki@...el.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>
Subject: [PATCH net-next v9 4/5] r8169: Use spinlock to guard config register locking

Right now r8169 doesn't have parallel access to its config register, but
the next patch makes the driver access config register at anytime.

So add a spinlock to protect the config register from any potential race.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
v9:
 - Replace mutex with spinlock so it can be used in softirq context.

v8:
 - Swap the place when using the mutex. Protect when config register is
   unlocked.

v7:
 - This is a new patch.

 drivers/net/ethernet/realtek/r8169_main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index a857650c2e82b..fb73b5386701f 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -613,6 +613,8 @@ struct rtl8169_private {
 		struct work_struct work;
 	} wk;
 
+	spinlock_t config_lock;
+
 	unsigned supports_gmii:1;
 	unsigned aspm_manageable:1;
 	dma_addr_t counters_phys_addr;
@@ -662,10 +664,12 @@ static inline struct device *tp_to_dev(struct rtl8169_private *tp)
 static void rtl_lock_config_regs(struct rtl8169_private *tp)
 {
 	RTL_W8(tp, Cfg9346, Cfg9346_Lock);
+	spin_unlock_bh(&tp->config_lock);
 }
 
 static void rtl_unlock_config_regs(struct rtl8169_private *tp)
 {
+	spin_lock_bh(&tp->config_lock);
 	RTL_W8(tp, Cfg9346, Cfg9346_Unlock);
 }
 
@@ -5217,6 +5221,8 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 		return rc;
 	}
 
+	spin_lock_init(&tp->config_lock);
+
 	tp->mmio_addr = pcim_iomap_table(pdev)[region];
 
 	xid = (RTL_R32(tp, TxConfig) >> 20) & 0xfcf;
-- 
2.34.1