From: Peter Zijlstra <peterz@infradead.org>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>, Tejun Heo <tj@kernel.org>,
Calvin Owens <calvinowens@fb.com>,
Thomas Gleixner <tglx@linutronix.de>,
Mel Gorman <mgorman@techsingularity.net>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/3] make printk work again
Date: Wed, 19 Oct 2016 14:21:08 +0200 [thread overview]
Message-ID: <20161019122108.GN3102@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20161019114828.GA414@swordfish>
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.
prev parent reply other threads:[~2016-10-19 14:20 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-18 17:08 [PATCH 0/3] make printk work again Peter Zijlstra
2016-10-18 17:08 ` [PATCH 1/3] printk: Fix kdb_trap_printk placement Peter Zijlstra
2016-10-19 14:41 ` Petr Mladek
2016-10-19 15:18 ` Peter Zijlstra
2016-10-20 13:02 ` Sergey Senozhatsky
2016-11-29 13:54 ` Petr Mladek
2016-10-18 17:08 ` [PATCH 2/3] early_printk: Add force_early_printk kernel parameter Peter Zijlstra
2016-11-29 14:02 ` Petr Mladek
2016-10-18 17:08 ` [PATCH 3/3] early_printk: Add simple serialization to early_vprintk() Peter Zijlstra
2016-10-18 17:19 ` Steven Rostedt
2016-10-18 17:30 ` Peter Zijlstra
2016-10-18 17:53 ` Steven Rostedt
2016-11-29 14:10 ` Petr Mladek
2016-10-19 7:04 ` [PATCH 0/3] make printk work again Jan Kara
2016-10-19 9:24 ` Peter Zijlstra
2016-10-19 11:48 ` Sergey Senozhatsky
2016-10-19 12:21 ` Peter Zijlstra [this message]
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