Re: [PATCH] printk/nmi: Prevent deadlock when serializing NMI backtraces

From: Sergey Senozhatsky
Date: Tue Jun 19 2018 - 21:58:45 EST


On (06/19/18 09:23), Steven Rostedt wrote:
> > On (06/19/18 09:52), Petr Mladek wrote:
> > > On Mon 2018-06-18 19:07:18, Sergey Senozhatsky wrote:
> > > > On (06/18/18 11:39), Petr Mladek wrote:
> > > > [..]
> > > >
> > > > Hmm. Can't answer right now :)
> > >
> > > Please, let me know what name you would like ;-)
> >
> > :) Wow, it's hard. Maybe we can derive some bits from the ftrace_dump()
> > function name? Dunno... Does printk_dump_nmi_enter() sound terrible?
> >
> > Maybe Steven has some opinions on this?
> >
>
> What exactly is the question?

Which one of these you'd prefer to see in ftrace_dump():

- printk_nmi_direct_enter() / printk_nmi_direct_exit()
- printk_chatty_nmi_enter() / printk_chatty_nmi_exit()
- printk_large_nmi_enter() / printk_large_nmi_exit()
- printk_dump_nmi_enter() / printk_dump_nmi_exit()

> Also, from a previous email in this thread, if you have to risk
> interleaved output to solve a deadlock, then just do that.

Yep.

-ss