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Re: [PATCH 0/3] make printk work again

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On Wed, Oct 19, 2016 at 08:48:28PM +0900, Sergey Senozhatsky wrote:
> On (10/18/16 19:08), Peter Zijlstra wrote:
> > This basically fixes printk by evading everything it does.
> > 
> > There's too many problems with printk, from sleeping locks to broken console
> > drivers. Stop using it.
> > 
> > The early_console drivers are the most robust and simple, use those.
> 
> ACK
> 
> Can we also please ban that pre Because it's a bit tricky.emption thing?

Ha, so that's actually quite complicated. The 3rd patch does what is
simple and robust. Doing more gets very tricky real quick.

So actual preemption is disabled per get_cpu()/put_cpu(), and cross-cpu
interleaving is disabled by that 'lock'. But interrupt (and NMI) nesting
are still possible.

It does sporadically happen, but I've not really found it to be a
problem when reading the output.

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[PATCH 0/3] make printk work again Peter Zijlstra <peterz@infradead.org> - 2016-10-18 19:20 +0200
  [PATCH 1/3] printk: Fix kdb_trap_printk placement Peter Zijlstra <peterz@infradead.org> - 2016-10-18 19:20 +0200
    Re: [PATCH 1/3] printk: Fix kdb_trap_printk placement Petr Mladek <pmladek@suse.com> - 2016-10-19 16:50 +0200
      Re: [PATCH 1/3] printk: Fix kdb_trap_printk placement Peter Zijlstra <peterz@infradead.org> - 2016-10-19 17:20 +0200
    Re: [PATCH 1/3] printk: Fix kdb_trap_printk placement Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-10-20 15:10 +0200
  [PATCH 3/3] early_printk: Add simple serialization to early_vprintk() Peter Zijlstra <peterz@infradead.org> - 2016-10-18 19:20 +0200
    Re: [PATCH 3/3] early_printk: Add simple serialization to  early_vprintk() Steven Rostedt <rostedt@goodmis.org> - 2016-10-18 19:30 +0200
      Re: [PATCH 3/3] early_printk: Add simple serialization to  early_vprintk() Peter Zijlstra <peterz@infradead.org> - 2016-10-18 19:40 +0200
        Re: [PATCH 3/3] early_printk: Add simple serialization to  early_vprintk() Steven Rostedt <rostedt@goodmis.org> - 2016-10-18 20:00 +0200
  [PATCH 2/3] early_printk: Add force_early_printk kernel parameter Peter Zijlstra <peterz@infradead.org> - 2016-10-18 19:20 +0200
  Re: [PATCH 0/3] make printk work again Peter Zijlstra <peterz@infradead.org> - 2016-10-19 16:30 +0200
  Re: [PATCH 0/3] make printk work again Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-10-19 16:30 +0200
  Re: [PATCH 0/3] make printk work again Jan Kara <jack@suse.cz> - 2016-10-19 17:00 +0200
    Re: [PATCH 0/3] make printk work again Peter Zijlstra <peterz@infradead.org> - 2016-10-19 18:20 +0200

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