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?
Sebastian
