在 2025/7/8 1:04, Sathyanarayanan Kuppuswamy 写道: > > On 7/7/25 3:30 AM, Andy Xu wrote: >> From: Hongbo Yao <andy.xu@xxxxxxxxxxxx> >> >> Extend the DPC recovery timeout from 4 seconds to 7 seconds to >> support Mellanox ConnectX series network adapters. >> >> My environment: >> - Platform: arm64 N2 based server >> - Endpoint1: Mellanox Technologies MT27800 Family [ConnectX-5] >> - Endpoint2: Mellanox Technologies MT2910 Family [ConnectX-7] >> >> With the original 4s timeout, hotplug would still be triggered: >> >> [ 81.012463] pcieport 0004:00:00.0: DPC: containment event, >> status:0x1f01 source:0x0000 >> [ 81.014536] pcieport 0004:00:00.0: DPC: unmasked uncorrectable error >> detected >> [ 81.029598] pcieport 0004:00:00.0: PCIe Bus Error: >> severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Receiver ID) >> [ 81.040830] pcieport 0004:00:00.0: device [0823:0110] error status/ >> mask=00008000/04d40000 >> [ 81.049870] pcieport 0004:00:00.0: [ 0] ERCR (First) >> [ 81.053520] pcieport 0004:00:00.0: AER: TLP Header: 60008010 010000ff >> 00001000 9c4c0000 >> [ 81.065793] mlx5_core 0004:01:00.0: mlx5_pci_err_detected Device >> state = 1 health sensors: 1 pci_status: 1. Enter, pci channel state = 2 >> [ 81.076183] mlx5_core 0004:01:00.0: mlx5_error_sw_reset:231:(pid >> 1618): start >> [ 81.083307] mlx5_core 0004:01:00.0: mlx5_error_sw_reset:252:(pid >> 1618): PCI channel offline, stop waiting for NIC IFC >> [ 81.077428] mlx5_core 0004:01:00.0: E-Switch: Disable: mode(LEGACY), >> nvfs(0), neovfs(0), active vports(0) >> [ 81.486693] mlx5_core 0004:01:00.0: mlx5_wait_for_pages:786:(pid >> 1618): Skipping wait for vf pages stage >> [ 81.496965] mlx5_core 0004:01:00.0: mlx5_wait_for_pages:786:(pid >> 1618): Skipping wait for vf pages stage >> [ 82.395040] mlx5_core 0004:01:00.1: print_health:819:(pid 0): Fatal >> error detected >> [ 82.395493] mlx5_core 0004:01:00.1: print_health_info:423:(pid 0): >> PCI slot 1 is unavailable >> [ 83.431094] mlx5_core 0004:01:00.0: mlx5_pci_err_detected Device >> state = 2 pci_status: 0. Exit, result = 3, need reset >> [ 83.442100] mlx5_core 0004:01:00.1: mlx5_pci_err_detected Device >> state = 2 health sensors: 1 pci_status: 1. Enter, pci channel state = 2 >> [ 83.441801] mlx5_core 0004:01:00.0: mlx5_crdump_collect:50:(pid >> 2239): crdump: failed to lock gw status -13 >> [ 83.454050] mlx5_core 0004:01:00.1: mlx5_error_sw_reset:231:(pid >> 1618): start >> [ 83.454050] mlx5_core 0004:01:00.1: mlx5_error_sw_reset:252:(pid >> 1618): PCI channel offline, stop waiting for NIC IFC >> [ 83.849429] mlx5_core 0004:01:00.1: E-Switch: Disable: mode(LEGACY), >> nvfs(0), neovfs(0), active vports(0) >> [ 83.858892] mlx5_core 0004:01:00.1: mlx5_wait_for_pages:786:(pid >> 1618): Skipping wait for vf pages stage >> [ 83.869464] mlx5_core 0004:01:00.1: mlx5_wait_for_pages:786:(pid >> 1618): Skipping wait for vf pages stage >> [ 85.201433] pcieport 0004:00:00.0: pciehp: Slot(41): Link Down >> [ 85.815016] mlx5_core 0004:01:00.1: mlx5_health_try_recover:335:(pid >> 2239): handling bad device here >> [ 85.824164] mlx5_core 0004:01:00.1: mlx5_error_sw_reset:231:(pid >> 2239): start >> [ 85.831283] mlx5_core 0004:01:00.1: mlx5_error_sw_reset:252:(pid >> 2239): PCI channel offline, stop waiting for NIC IFC >> [ 85.841899] mlx5_core 0004:01:00.1: mlx5_unload_one_dev_locked:1612: >> (pid 2239): mlx5_unload_one_dev_locked: interface is down, NOP >> [ 85.853799] mlx5_core 0004:01:00.1: mlx5_health_wait_pci_up:325:(pid >> 2239): PCI channel offline, stop waiting for PCI >> [ 85.863494] mlx5_core 0004:01:00.1: mlx5_health_try_recover:338:(pid >> 2239): health recovery flow aborted, PCI reads still not working >> [ 85.873231] mlx5_core 0004:01:00.1: mlx5_pci_err_detected Device >> state = 2 pci_status: 0. Exit, result = 3, need reset >> [ 85.879899] mlx5_core 0004:01:00.1: E-Switch: Unload vfs: >> mode(LEGACY), nvfs(0), neovfs(0), active vports(0) >> [ 85.921428] mlx5_core 0004:01:00.1: E-Switch: Disable: mode(LEGACY), >> nvfs(0), neovfs(0), active vports(0) >> [ 85.930491] mlx5_core 0004:01:00.1: mlx5_wait_for_pages:786:(pid >> 1617): Skipping wait for vf pages stage >> [ 85.940849] mlx5_core 0004:01:00.1: mlx5_wait_for_pages:786:(pid >> 1617): Skipping wait for vf pages stage >> [ 85.949971] mlx5_core 0004:01:00.1: mlx5_uninit_one:1528:(pid 1617): >> mlx5_uninit_one: interface is down, NOP >> [ 85.959944] mlx5_core 0004:01:00.1: E-Switch: cleanup >> [ 86.035541] mlx5_core 0004:01:00.0: E-Switch: Unload vfs: >> mode(LEGACY), nvfs(0), neovfs(0), active vports(0) >> [ 86.077568] mlx5_core 0004:01:00.0: E-Switch: Disable: mode(LEGACY), >> nvfs(0), neovfs(0), active vports(0) >> [ 86.071727] mlx5_core 0004:01:00.0: mlx5_wait_for_pages:786:(pid >> 1617): Skipping wait for vf pages stage >> [ 86.096577] mlx5_core 0004:01:00.0: mlx5_wait_for_pages:786:(pid >> 1617): Skipping wait for vf pages stage >> [ 86.106909] mlx5_core 0004:01:00.0: mlx5_uninit_one:1528:(pid 1617): >> mlx5_uninit_one: interface is down, NOP >> [ 86.115940] pcieport 0004:00:00.0: AER: subordinate device reset failed >> [ 86.122557] pcieport 0004:00:00.0: AER: device recovery failed >> [ 86.128571] mlx5_core 0004:01:00.0: E-Switch: cleanup >> >> I added some prints and found that: >> - ConnectX-5 requires >5s for full recovery >> - ConnectX-7 requires >6s for full recovery >> >> Setting timeout to 7s covers both devices with safety margin. > > > Instead of updating the recovery time, can you check why your device > recovery takes > such a long time and how to fix it from the device end? > Hi, Sathyanarayanan. Thanks for the valuable feedback and suggestions. I fully agree that ideally the root cause should be addressed on the device side to reduce the DPC recovery latency, and that waiting longer in the kernel is not a perfect solution. However, the current 4 seconds timeout in pci_dpc_recovered() is indeed an empirical value rather than a hard requirement from the PCIe specification. In real-world scenarios, like with Mellanox ConnectX-5/7 adapters, we've observed that full DPC recovery can take more than 5-6 seconds, which leads to premature hotplug processing and device removal. To improve robustness and maintain flexibility, I’m considering introducing a module parameter to allow tuning the DPC recovery timeout dynamically. Would you like me to prepare and submit such a patch for review? Best regards, Hongbo Yao > >> Signed-off-by: Hongbo Yao <andy.xu@xxxxxxxxxxxx> >> --- >> drivers/pci/pcie/dpc.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c >> index fc18349614d7..35a37fd86dcd 100644 >> --- a/drivers/pci/pcie/dpc.c >> +++ b/drivers/pci/pcie/dpc.c >> @@ -118,10 +118,10 @@ bool pci_dpc_recovered(struct pci_dev *pdev) >> /* >> * Need a timeout in case DPC never completes due to failure of >> * dpc_wait_rp_inactive(). The spec doesn't mandate a time limit, >> - * but reports indicate that DPC completes within 4 seconds. >> + * but reports indicate that DPC completes within 7 seconds. >> */ >> wait_event_timeout(dpc_completed_waitqueue, dpc_completed(pdev), >> - msecs_to_jiffies(4000)); >> + msecs_to_jiffies(7000)); >> return test_and_clear_bit(PCI_DPC_RECOVERED, &pdev->priv_flags); >> } >
