Re: [PATCH 10/10] Replace tasklets with workqueues

[Maksym Planeta]

Hi,

this is a kind reminder regarding the patchset. I added description of 
races in the original email.

On 30/07/2019 21:20, Maksym Planeta wrote:
> On 25/07/2019 20:50, Jason Gunthorpe wrote:
> > On Thu, Jul 25, 2019 at 04:36:20PM +0200, Maksym Planeta wrote:
> > > Is this one better?
> > >
> > > Replace tasklets with workqueues in rxe driver. The reason for this
> > > replacement is that tasklets are supposed to run atomically, although 
> > > the
> > > actual code may block.
> > >
> > > Modify the SKB destructor for outgoing SKB's to schedule QP tasks 
> > > only if
> > > the QP is not destroyed itself.
> > >
> > > Add a variable "pending_skb_down" to ensure that reference counting 
> > > for a QP
> > > is decremented only when QP access related to this skb is over.
> > >
> > > Separate part of pool element cleanup code to allow this code to be 
> > > called
> > > in the very end of cleanup, even if some of cleanup is scheduled for
> > > asynchronous execution. Example, when it was happening is destructor 
> > > for a
> > > QP.
> > >
> > > Disallow calling of task functions "directly". This allows to 
> > > simplify logic
> > > inside rxe_task.c
> > >
> > > Schedule rxe_qp_do_cleanup onto high-priority system workqueue, 
> > > because this
> > > function can be scheduled from normal system workqueue.
> > >
> > > Before destroying a QP, wait until all references to this QP are gone.
> > > Previously the problem was that outgoing SKBs could be freed after 
> > > the QP
> > > these SKBs refer to is destroyed.
> > >
> > > Add blocking rxe_run_task to replace __rxe_do_task that was calling task
> > > function directly.
> >
> > Mostly but it would also be good to describe the use after free and
> > races more specifically
>
> These situations are described in the cover letter (PATCH 00/10). Do you 
> need a more detailed description than that?
>
> > Jason

--
Regards,
Maksym Planeta