Re: [PATCH] char/random: silence a lockdep splat with printk()

From: Sergey Senozhatsky
Date: Wed Dec 04 2019 - 20:01:00 EST


Hi,

On (19/12/03 13:46), Qian Cai wrote:
> > On Nov 13, 2019, at 4:16 PM, Qian Cai <cai@xxxxxx> wrote:
> >
> > From: Sergey Senozhatsky <sergey.senozhatsky.work@xxxxxxxxx>
> >
> > Sergey didn't like the locking order,
> >
> > uart_port->lock -> tty_port->lock
> >
> > uart_write (uart_port->lock)
> > __uart_start
> > pl011_start_tx
> > pl011_tx_chars
> > uart_write_wakeup
> > tty_port_tty_wakeup
> > tty_port_default
> > tty_port_tty_get (tty_port->lock)
> >
> > but those code is so old, and I have no clue how to de-couple it after
> > checking other locks in the splat. There is an onging effort to make all
> > printk() as deferred, so until that happens, workaround it for now as a
> > short-term fix.
>
> Sergey, could we have a ACK from you so Ted might be able to merge?

Not sure if I can ACK it, but overall it makes sense to use deferred
printk there.

[..]
>
> > [cai@xxxxxx: add a commit log.]
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky.work@xxxxxxxxx>
> > Signed-off-by: Qian Cai <cai@xxxxxx>
> > ---
> >
> > Sergey, please let us know if you are fine with the Signed-off-by.

A 'Reviewed-by' will suffice.

Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>

-ss