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Date: Tue, 12 Dec 2017 15:51:05 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Ilia Mirkin <imirkin@...m.mit.edu>
Cc: Ingo Molnar <mingo@...nel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Pekka Paalanen <ppaalanen@...il.com>, Lyude <lyude@...hat.com>,
Steven Rostedt <rostedt@...dmis.org>,
Thomas Gleixner <tglx@...utronix.de>,
Karol Herbst <kherbst@...hat.com>,
Linus Torvalds <torvalds@...ux-foundation.org>, hpa@...or.com,
linux-tip-commits@...r.kernel.org,
Karol Herbst <karolherbst@...il.com>
Subject: Re: [tip:x86/urgent] x86/mm/kmmio: Fix mmiotrace for page unaligned
addresses
On Tue, Dec 12, 2017 at 09:47:05AM -0500, Ilia Mirkin wrote:
> > So this 'thing' has huge gaping SMP holes in.
>
> Sure does! Probably why the following happens when mmiotrace is enabled:
>
> void enable_mmiotrace(void)
> {
> mutex_lock(&mmiotrace_mutex);
> if (is_enabled())
> goto out;
>
> if (nommiotrace)
> pr_info("MMIO tracing disabled.\n");
> kmmio_init();
> enter_uniprocessor();
^^^^^
Ah! I completely missed that. OK, that makes it much less broken :-)
If I don't forget, I'll add some comments to this file to clarify that.
Thanks!
> spin_lock_irq(&trace_lock);
> atomic_inc(&mmiotrace_enabled);
> spin_unlock_irq(&trace_lock);
> pr_info("enabled.\n");
> out:
> mutex_unlock(&mmiotrace_mutex);
> }
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