Re: [PATCH] qed: fix possible unpaired spin_{un}lock_bh in _qed_mcp_cmd_and_union()

[Jakub Kicinski]

On Tue, 20 Jul 2021 02:02:26 +0000, Justin He wrote:
> > > For instance:
> > > _qed_mcp_cmd_and_union()
> > >   In while loop
> > >     spin_lock_bh()
> > >     qed_mcp_has_pending_cmd() (assume false), will break the loop  
> > 
> > I agree till here.
> >   
> > >   if (cnt >= max_retries) {
> > > ...
> > >     return -EAGAIN; <-- here returns -EAGAIN without invoking bh unlock
> > >   }
> > >  
> > 
> > Because of break, cnt has not been increased.
> >    - cnt is still less than max_retries.
> >   - if (cnt >= max_retries) will not be *true*, leading to spin_unlock_bh().
> > Hence pairing completed.  
> 
> Sorry, indeed. Let me check other possibilities.
> @David S. Miller Sorry for the inconvenience, could you please revert it
> in netdev tree?

Please submit a revert patch with the conclusions from the discussion
included in the commit message.