RE: [Intel-wired-lan] [PATCH net] iavf: Fix deadlock in initialization

[Jankowski, Konrad0]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@xxxxxxxxxx> On Behalf Of
> Ivan Vecera
> Sent: Monday, August 8, 2022 7:59 PM
> To: netdev@xxxxxxxxxxxxxxx
> Cc: moderated list:INTEL ETHERNET DRIVERS <intel-wired-
> lan@xxxxxxxxxxxxxxxx>; Brandeburg, Jesse <jesse.brandeburg@xxxxxxxxx>;
> open list <linux-kernel@xxxxxxxxxxxxxxx>; Stefan Assmann
> <sassmann@xxxxxxxxx>; Eric Dumazet <edumazet@xxxxxxxxxx>; Jakub
> Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni <pabeni@xxxxxxxxxx>; David S.
> Miller <davem@xxxxxxxxxxxxx>
> Subject: [Intel-wired-lan] [PATCH net] iavf: Fix deadlock in initialization
> 
> Fix deadlock that occurs when iavf interface is a part of failover configuration.
> 
> 1. Mutex crit_lock is taken at the beginning of iavf_watchdog_task() 2.
> Function iavf_init_config_adapter() is called when adapter
>    state is __IAVF_INIT_CONFIG_ADAPTER
> 3. iavf_init_config_adapter() calls register_netdevice() that emits
>    NETDEV_REGISTER event
> 4. Notifier function failover_event() then calls
>    net_failover_slave_register() that calls dev_open() 5. dev_open() calls
> iavf_open() that tries to take crit_lock in
>    end-less loop
> 
> Stack trace:
> ...
> [  790.251876]  usleep_range_state+0x5b/0x80 [  790.252547]
> iavf_open+0x37/0x1d0 [iavf] [  790.253139]  __dev_open+0xcd/0x160 [
> 790.253699]  dev_open+0x47/0x90 [  790.254323]
> net_failover_slave_register+0x122/0x220 [net_failover] [  790.255213]
> failover_slave_register.part.7+0xd2/0x180 [failover] [  790.256050]
> failover_event+0x122/0x1ab [failover] [  790.256821]
> notifier_call_chain+0x47/0x70 [  790.257510]
> register_netdevice+0x20f/0x550 [  790.258263]
> iavf_watchdog_task+0x7c8/0xea0 [iavf] [  790.259009]
> process_one_work+0x1a7/0x360 [  790.259705]  worker_thread+0x30/0x390
> 
> To fix the situation we should check the current adapter state after first
> unsuccessful mutex_trylock() and return with -EBUSY if it is
> __IAVF_INIT_CONFIG_ADAPTER.
> 
> Fixes: 226d528512cf ("iavf: fix locking of critical sections")
> Signed-off-by: Ivan Vecera <ivecera@xxxxxxxxxx>
> ---
>  drivers/net/ethernet/intel/iavf/iavf_main.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c
> b/drivers/net/ethernet/intel/iavf/iavf_main.c
> index 45d097a164ad..f9dcaadc7ea0 100644
> --- a/drivers/net/ethernet/intel/iavf/iavf_main.c
> +++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
> @@ -4085,8 +4085,17 @@ static int iavf_open(struct net_device *netdev)

Tested-by: Konrad Jankowski <konrad0.jankowski@xxxxxxxxx>