From: Yong Zhang <yong.zhang0@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>
Subject: Re: [PATCH -rt] printk: Don't emit console_cpu_notify() for CPU_DYING
Date: Thu, 17 Nov 2011 13:29:06 +0800 [thread overview]
Message-ID: <20111117052906.GC14492@zhy> (raw)
In-Reply-To: <alpine.LFD.2.02.1111161547560.4902@ionos>
On Wed, Nov 16, 2011 at 03:48:11PM +0100, Thomas Gleixner wrote:
> On Wed, 16 Nov 2011, Steven Rostedt wrote:
> > Thomas, doesn't printk not print to serial in atomic contexts? Or did
I guess you mean console_trylock_for_printk() will fail in atomic context?
If so, yeah, that doesn't change.
But the issue is console_cpu_notify() call console_lock() directly.
That means below scenario could also happen in mainline:
CPU A CPU B
doing printk with console_sem held
take_cpu_down();
cpu_notify(CPU_DYING);
console_cpu_notify();
console_lock();
down(&console_sem);
*bang*
up(&console_sem);
Sounds I should also send this patch to mainline.
Thanks,
Yong
prev parent reply other threads:[~2011-11-17 5:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-16 9:42 [PATCH -rt] printk: Don't emit console_cpu_notify() for CPU_DYING Yong Zhang
2011-11-16 14:19 ` Steven Rostedt
2011-11-16 14:48 ` Thomas Gleixner
2011-11-17 5:29 ` Yong Zhang [this message]
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