[PATCH net] r8169: fix DMA being used after buffer free if WoL is enabled

IOMMU errors have been reported if WoL is enabled and interface is
brought down. It turned out that the network chip triggers DMA
transfers after the DMA buffers have been freed. For WoL to work we
need to leave rx enabled, therefore simply stop the chip from being
a DMA busmaster.

Fixes: 567ca57faa62 ("r8169: add rtl8169_up")
Tested-by: Paul Blazejowski <redacted>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 8ea6ddc7d..0d7001303 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c

@@ -4644,6 +4644,9 @@ static void rtl8169_down(struct rtl8169_private *tp)
 
 	rtl8169_update_counters(tp);
 
+	pci_clear_master(tp->pci_dev);
+	rtl_pci_commit(tp);
+
 	rtl8169_cleanup(tp, true);
 
 	rtl_prepare_power_down(tp);

@@ -4651,6 +4654,7 @@ static void rtl8169_down(struct rtl8169_private *tp)
 
 static void rtl8169_up(struct rtl8169_private *tp)
 {
+	pci_set_master(tp->pci_dev);
 	phy_resume(tp->phydev);
 	rtl8169_init_phy(tp);
 	napi_enable(&tp->napi);

@@ -5305,8 +5309,6 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	rtl_hw_reset(tp);
 
-	pci_set_master(pdev);
-
 	rc = rtl_alloc_irq(tp);
 	if (rc < 0) {
 		dev_err(&pdev->dev, "Can't allocate interrupt\n");

-- 
2.31.0

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Sat, 20 Mar 2021 21:40:08 +0100 you wrote:

IOMMU errors have been reported if WoL is enabled and interface is
brought down. It turned out that the network chip triggers DMA
transfers after the DMA buffers have been freed. For WoL to work we
need to leave rx enabled, therefore simply stop the chip from being
a DMA busmaster.

Fixes: 567ca57faa62 ("r8169: add rtl8169_up")
Tested-by: Paul Blazejowski <redacted>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>

[...]

Here is the summary with links:
  - [net] r8169: fix DMA being used after buffer free if WoL is enabled
    https://git.kernel.org/netdev/net/c/f658b90977d2

You are awesome, thank you!
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