Re: [dpdk-dev] [PATCH 1/2] kni: fix kernel deadlock when using mlx devices

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 2/25/2021 2:32 PM, Elad Nachman wrote:
> This first part of v4 of the patch re-introduces Stephen Hemminger's
> patch 64106 . This part changes the parameter kni_net_process_request()
> gets and introduces the initial rtnl unlocking mechanism.
> 
> Signed-off-by: Elad Nachman <eladv6@gmail.com>
> ---
> v4:
> * for if down case, send asynchronously with rtnl locked and without
>    wait, returning immediately to avoid both kernel race conditions
>    and deadlock in user-space
> v3:
> * Include original patch and new patch as a series of patch, added a
>    comment to the new patch
> v2:
> * rebuild the patch as increment from patch 64106
> * fix comment and blank lines

<...>

>   
> +	/* Since we need to wait and RTNL mutex is held
> +	 * drop the mutex and hold reference to keep device
> +	 */
> +	dev_hold(dev);
> +	rtnl_unlock();
> +
>   	ret_val = wait_event_interruptible_timeout(kni->wq,
>   			kni_fifo_count(kni->resp_q), 3 * HZ);
> +	rtnl_lock();
> +	dev_put(dev);
> +

Hi Elad,

Let's drop rtnl lock/unlock form this patch, it will be changed in next patch 
already, and make this patch only function parameter change, as preparation to 
actual change.