Re: [PATCH V2 net 4/4] net: hns3: fix deadlock issue when externel_lb and reset are executed together

[Leon Romanovsky]

On Mon, Aug 07, 2023 at 07:34:52PM +0800, Jijie Shao wrote:
> From: Yonglong Liu <liuyonglong@xxxxxxxxxx>
> 
> When externel_lb and reset are executed together, a deadlock may
> occur:
> [ 3147.217009] INFO: task kworker/u321:0:7 blocked for more than 120 seconds.
> [ 3147.230483] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 3147.238999] task:kworker/u321:0  state:D stack:    0 pid:    7 ppid:     2 flags:0x00000008
> [ 3147.248045] Workqueue: hclge hclge_service_task [hclge]
> [ 3147.253957] Call trace:
> [ 3147.257093]  __switch_to+0x7c/0xbc
> [ 3147.261183]  __schedule+0x338/0x6f0
> [ 3147.265357]  schedule+0x50/0xe0
> [ 3147.269185]  schedule_preempt_disabled+0x18/0x24
> [ 3147.274488]  __mutex_lock.constprop.0+0x1d4/0x5dc
> [ 3147.279880]  __mutex_lock_slowpath+0x1c/0x30
> [ 3147.284839]  mutex_lock+0x50/0x60
> [ 3147.288841]  rtnl_lock+0x20/0x2c
> [ 3147.292759]  hclge_reset_prepare+0x68/0x90 [hclge]
> [ 3147.298239]  hclge_reset_subtask+0x88/0xe0 [hclge]
> [ 3147.303718]  hclge_reset_service_task+0x84/0x120 [hclge]
> [ 3147.309718]  hclge_service_task+0x2c/0x70 [hclge]
> [ 3147.315109]  process_one_work+0x1d0/0x490
> [ 3147.319805]  worker_thread+0x158/0x3d0
> [ 3147.324240]  kthread+0x108/0x13c
> [ 3147.328154]  ret_from_fork+0x10/0x18
> 
> In externel_lb process, the hns3 driver call napi_disable()
> first, then the reset happen, then the restore process of the
> externel_lb will fail, and will not call napi_enable(). When
> doing externel_lb again, napi_disable() will be double call,
> cause a deadlock of rtnl_lock().
> 
> This patch use the HNS3_NIC_STATE_DOWN state to protect the
> calling of napi_disable() and napi_enable() in externel_lb
> process, just as the usage in ndo_stop() and ndo_start().
> 
> Fixes: 04b6ba143521 ("net: hns3: add support for external loopback test")
> Signed-off-by: Yonglong Liu <liuyonglong@xxxxxxxxxx>
> Signed-off-by: Jijie Shao <shaojijie@xxxxxxxxxx>
> ---
>  drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 

Thanks,
Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxx>