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charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: kwepems100002.china.huawei.com (7.221.188.206) To kwepemk100013.china.huawei.com (7.202.194.61) on 2025/8/1 18:05, Simon Horman wrote: > On Thu, Jul 31, 2025 at 09:47:47PM +0800, Jijie Shao wrote: >> Currently, the hibmcge netdev acquires the rtnl_lock in >> pci_error_handlers.reset_prepare() and releases it in >> pci_error_handlers.reset_done(). >> >> However, in the PCI framework: >> pci_reset_bus - __pci_reset_slot - pci_slot_save_and_disable_locked - >> pci_dev_save_and_disable - err_handler->reset_prepare(dev); >> >> In pci_slot_save_and_disable_locked(): >> list_for_each_entry(dev, &slot->bus->devices, bus_list) { >> if (!dev->slot || dev->slot!= slot) >> continue; >> pci_dev_save_and_disable(dev); >> if (dev->subordinate) >> pci_bus_save_and_disable_locked(dev->subordinate); >> } >> >> This will iterate through all devices under the current bus and execute >> err_handler->reset_prepare(), causing two devices of the hibmcge driver >> to sequentially request the rtnl_lock, leading to a deadlock. >> >> Since the driver now executes netif_device_detach() >> before the reset process, it will not concurrently with >> other netdev APIs, so there is no need to hold the rtnl_lock now. >> >> Therefore, this patch removes the rtnl_lock during the reset process and >> adjusts the position of HBG_NIC_STATE_RESETTING to ensure >> that multiple resets are not executed concurrently. >> >> Fixes: 3f5a61f6d504f ("net: hibmcge: Add reset supported in this module") >> Signed-off-by: Jijie Shao >> --- >> drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c | 13 ++++--------- >> 1 file changed, 4 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c b/drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c >> index 503cfbfb4a8a..94bc6f0da912 100644 >> --- a/drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c >> +++ b/drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c >> @@ -53,9 +53,11 @@ static int hbg_reset_prepare(struct hbg_priv *priv, enum hbg_reset_type type) >> { >> int ret; >> >> - ASSERT_RTNL(); >> + if (test_and_set_bit(HBG_NIC_STATE_RESETTING, &priv->state)) >> + return -EBUSY; >> >> if (netif_running(priv->netdev)) { >> + clear_bit(HBG_NIC_STATE_RESETTING, &priv->state); >> dev_warn(&priv->pdev->dev, >> "failed to reset because port is up\n"); >> return -EBUSY; >> @@ -64,7 +66,6 @@ static int hbg_reset_prepare(struct hbg_priv *priv, enum hbg_reset_type type) >> netif_device_detach(priv->netdev); >> >> priv->reset_type = type; >> - set_bit(HBG_NIC_STATE_RESETTING, &priv->state); >> clear_bit(HBG_NIC_STATE_RESET_FAIL, &priv->state); >> ret = hbg_hw_event_notify(priv, HBG_HW_EVENT_RESET); >> if (ret) { >> @@ -84,10 +85,8 @@ static int hbg_reset_done(struct hbg_priv *priv, enum hbg_reset_type type) >> type != priv->reset_type) >> return 0; >> >> - ASSERT_RTNL(); >> - >> - clear_bit(HBG_NIC_STATE_RESETTING, &priv->state); >> ret = hbg_rebuild(priv); >> + clear_bit(HBG_NIC_STATE_RESETTING, &priv->state); > Hi Jijie, > > If I understand things correctly, then with this patch the > HBG_NIC_STATE_RESETTING bit is used to prevent concurrent execution. > > Noting that a reset may be triggered via eththool, where hbg_reset() is > used as a callback, I am concerned about concurrency implications for lines > below this one. Yes, just like the following, it can lead to reset and net open concurrency. =========== reset1 reset2 open set_bit HBG_NIC_STATE_RESETTING netif_device_detach() resetting... clear_bit HBG_NIC_STATE_RESETTING set_bit HBG_NIC_STATE_RESETTING netif_device_detach() netif_device_attach() resetting... hbg_net_open() hbg_txrx_init() clear_bit HBG_NIC_STATE_RESETTING netif_device_attach() ============ Thank you for your reminder. I will fix it in V2 Jijie Shao >> if (ret) { >> priv->stats.reset_fail_cnt++; >> set_bit(HBG_NIC_STATE_RESET_FAIL, &priv->state); >> @@ -101,12 +100,10 @@ static int hbg_reset_done(struct hbg_priv *priv, enum hbg_reset_type type) >> return ret; >> } >> >> -/* must be protected by rtnl lock */ >> int hbg_reset(struct hbg_priv *priv) >> { >> int ret; >> >> - ASSERT_RTNL(); >> ret = hbg_reset_prepare(priv, HBG_RESET_TYPE_FUNCTION); >> if (ret) >> return ret; >> @@ -171,7 +168,6 @@ static void hbg_pci_err_reset_prepare(struct pci_dev *pdev) >> struct net_device *netdev = pci_get_drvdata(pdev); >> struct hbg_priv *priv = netdev_priv(netdev); >> >> - rtnl_lock(); >> hbg_reset_prepare(priv, HBG_RESET_TYPE_FLR); >> } >> >> @@ -181,7 +177,6 @@ static void hbg_pci_err_reset_done(struct pci_dev *pdev) >> struct hbg_priv *priv = netdev_priv(netdev); >> >> hbg_reset_done(priv, HBG_RESET_TYPE_FLR); >> - rtnl_unlock(); >> } >> >> static const struct pci_error_handlers hbg_pci_err_handler = { >> -- >> 2.33.0 >>