netdev - [PATCH v8 RESEND 5/6] r8169: Use mutex to guard config register locking

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Message-Id: <20230221023849.1906728-6-kai.heng.feng@canonical.com>
Date:   Tue, 21 Feb 2023 10:38:48 +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 v8 RESEND 5/6] r8169: Use mutex 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 mutex to protect the config register from any potential race.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
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 e40498dd08d17..897f90b48bba6 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;
 
+	struct mutex 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);
+	mutex_unlock(&tp->config_lock);
 }
 
 static void rtl_unlock_config_regs(struct rtl8169_private *tp)
 {
+	mutex_lock(&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;
 	}
 
+	mutex_init(&tp->config_lock);
+
 	tp->mmio_addr = pcim_iomap_table(pdev)[region];
 
 	xid = (RTL_R32(tp, TxConfig) >> 20) & 0xfcf;
-- 
2.34.1