Re: [PATCH 1/2] igc: don't rd/wr iomem when PCI is removed
From: Pali Rohár <pali@kernel.org>
Date: 2021-07-04 14:28:16
Also in:
intel-wired-lan, linux-pci, lkml
+ Bjorn, Krzysztof and linux-pci On Friday 02 July 2021 12:51:19 Aaron Ma wrote:
quoted hunk ↗ jump to hunk
Check PCI state when rd/wr iomem. Implement wr32 function as rd32 too. When unplug TBT dock with i225, rd/wr PCI iomem will cause error log: Trace: BUG: unable to handle page fault for address: 000000000000b604 Oops: 0000 [#1] SMP NOPTI RIP: 0010:igc_rd32+0x1c/0x90 [igc] Call Trace: igc_ptp_suspend+0x6c/0xa0 [igc] igc_ptp_stop+0x12/0x50 [igc] igc_remove+0x7f/0x1c0 [igc] pci_device_remove+0x3e/0xb0 __device_release_driver+0x181/0x240 Signed-off-by: Aaron Ma <redacted> --- drivers/net/ethernet/intel/igc/igc_main.c | 16 ++++++++++++++++ drivers/net/ethernet/intel/igc/igc_regs.h | 7 ++----- 2 files changed, 18 insertions(+), 5 deletions(-)diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index f1adf154ec4a..606b72cb6193 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c@@ -5292,6 +5292,10 @@ u32 igc_rd32(struct igc_hw *hw, u32 reg) u8 __iomem *hw_addr = READ_ONCE(hw->hw_addr); u32 value = 0; + if (igc->pdev && + igc->pdev->error_state == pci_channel_io_perm_failure)
Hello! This code pattern and commit message looks like that we could use pci_dev_is_disconnected() helper function for checking if device is still connected or was disconnected. Apparently pci_dev_is_disconnected() is defined only in private header file drivers/pci/pci.h and not in public include/linux/pci.h. Aaron: can you check if pci_dev_is_disconnected() is really something which should be used and it helps you? Bjorn, Krzysztof: what do you think about lifting helper function pci_dev_is_disconnected() to be available to all drivers and not only in PCI subsystem? I think that such helper function makes driver code more readable and can be useful also for other drivers which are checking if return value is all F's.
+ return 0;
Aaron: should not you return all F's on error? Because few lines below in this function is returned value with all F's when PCIe link lost.
+ value = readl(&hw_addr[reg]);
Anyway, this code looks to be racy. When pci_channel_io_perm_failure is set (e.g. by hotplug interrupt) after checking for pdev->error_state and prior executing above readl() then mentioned fatal error still occurs.
quoted hunk ↗ jump to hunk
/* reads should not return all F's */@@ -5308,6 +5312,18 @@ u32 igc_rd32(struct igc_hw *hw, u32 reg) return value; } +void igc_wr32(struct igc_hw *hw, u32 reg, u32 val) +{ + struct igc_adapter *igc = container_of(hw, struct igc_adapter, hw); + u8 __iomem *hw_addr = READ_ONCE(hw->hw_addr); + + if (igc->pdev && + igc->pdev->error_state == pci_channel_io_perm_failure) + return; + + writel((val), &hw_addr[(reg)]); +} + int igc_set_spd_dplx(struct igc_adapter *adapter, u32 spd, u8 dplx) { struct igc_mac_info *mac = &adapter->hw.mac;diff --git a/drivers/net/ethernet/intel/igc/igc_regs.h b/drivers/net/ethernet/intel/igc/igc_regs.h index cc174853554b..eb4be87d0e8b 100644 --- a/drivers/net/ethernet/intel/igc/igc_regs.h +++ b/drivers/net/ethernet/intel/igc/igc_regs.h@@ -260,13 +260,10 @@ struct igc_hw; u32 igc_rd32(struct igc_hw *hw, u32 reg); /* write operations, indexed using DWORDS */ -#define wr32(reg, val) \ -do { \ - u8 __iomem *hw_addr = READ_ONCE((hw)->hw_addr); \ - writel((val), &hw_addr[(reg)]); \ -} while (0) +void igc_wr32(struct igc_hw *hw, u32 reg, u32 val); #define rd32(reg) (igc_rd32(hw, reg)) +#define wr32(reg, val) (igc_wr32(hw, reg, val)) #define wrfl() ((void)rd32(IGC_STATUS))-- 2.30.2