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

[Justin He]

> -----Original Message-----
> From: Jakub Kicinski <kuba@xxxxxxxxxx>
> Sent: Tuesday, July 20, 2021 5:06 PM
> To: Justin He <Justin.He@xxxxxxx>
> Cc: Prabhakar Kushwaha <prabhakar.pkin@xxxxxxxxx>; David S. Miller
> <davem@xxxxxxxxxxxxx>; Ariel Elior <aelior@xxxxxxxxxxx>; GR-everest-linux-
> l2@xxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; Linux Kernel Mailing List <linux-
> kernel@xxxxxxxxxxxxxxx>; nd <nd@xxxxxxx>; Shai Malin <malin1024@xxxxxxxxx>;
> Shai Malin <smalin@xxxxxxxxxxx>; Prabhakar Kushwaha <pkushwaha@xxxxxxxxxxx>
> Subject: Re: [PATCH] qed: fix possible unpaired spin_{un}lock_bh in
> _qed_mcp_cmd_and_union()
> 
> 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.
Okay，will do that
Thanks for the reminder

--
Cheers,
Justin (Jia He)