On 2018-06-22 16:26:48 [+0200], Daniel Wagner wrote:
> On 06/22/2018 04:15 PM, Sebastian Andrzej Siewior wrote:
> > On 2018-06-22 15:56:42 [+0200], Daniel Wagner wrote:
> > > From: Daniel Wagner <daniel.wagner@xxxxxxxxxxx>
> > >
> > > [ Upstream commit 8afb1d2c12163f77777f84616a8e9444d0050ebe ]
> > >
> > > Commit 40f70c03e33a ("serial: sh-sci: add locking to console write
> > > function to avoid SMP lockup") copied the strategy to avoid locking
> > > problems in conjuncture with the console from the UART8250
> > > driver. Instead using directly spin_{try}lock_irqsave(),
> > > local_irq_save() followed by spin_{try}lock() was used. While this is
> > > correct on mainline, for -rt it is a problem. spin_{try}lock() will
> > > check if it is running in a valid context. Since the local_irq_save()
> > > has already been executed, the context has changed and
> > > spin_{try}lock() will complain. The reason why spin_{try}lock()
> > > complains is that on -rt the spin locks are turned into mutexes and
> > > therefore can sleep. Sleeping with interrupts disabled is not valid.
> >
> > This change only effects RT. Usually I don't bother Greg/stable team
> > which changes which went upstream and help/fix RT but don't affect (as
> > in fix) non-RT code.
> > I usually add them to the RT queue and let RT-stable team pick it up. So
> > I would suggest I pick it up for v4.16 and it gets then picked up the
> > RT-stable team.
> > Any objections?
>
> I don't mind for all non 4.4 versions. The 4.4 is special for me. Ben will
> merge the stable into the cip tree and I merge the -rt patches on top the
> cip-rt tree. That's why I would like to get the patch via the stable tree.
Does Ben need this patch in CIP?
Sebastian
