linux-kernel - Re: [RFC][PATCH] printk: Fixup the nmi printk mess

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Date:	Wed, 10 Jun 2015 11:54:11 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Petr Mladek <pmladek@...e.cz>, linux-kernel@...r.kernel.org,
	jkosina@...e.cz, paulmck@...ux.vnet.ibm.com,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RFC][PATCH] printk: Fixup the nmi printk mess

On Wed, 10 Jun 2015 17:32:53 +0200
Peter Zijlstra <peterz@...radead.org> wrote:

> > Note that the backtraces used to be serialized via
> > static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED
> > in the past. See the commit
> > a9edc8809328 ("x86/nmi: Perform a safe NMI stack trace on all CPUs")
> 
> We could easily add a static raw_spinlock_t to __printk_nmi_flush() and
> serialize its invocations if people think that is important.

Yes please. One thing about the original change is that it made the NMI
backtraces readable. I hated the interleaving of the backtraces, as it
made it almost impossible to to debug.

-- Steve
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