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 <redacted>
---
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.