linux-kernel - RE: [PATCH v3 4/9] ACPI, x86: Extended error log driver for x86 platform

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Date:	Fri, 27 Jun 2014 20:43:14 +0000
From:	"Luck, Tony" <tony.luck@...el.com>
To:	Borislav Petkov <bp@...en8.de>, Xie XiuQi <xiexiuqi@...wei.com>
CC:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
	"Chen, Gong" <gong.chen@...ux.intel.com>,
	"joe@...ches.com" <joe@...ches.com>,
	"m.chehab@...sung.com" <m.chehab@...sung.com>,
	"arozansk@...hat.com" <arozansk@...hat.com>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Li Bin <huawei.libin@...wei.com>
Subject: RE: [PATCH v3 4/9] ACPI, x86: Extended error log driver for x86
 platform

>> There's a logbuf_lock in printk. If logbuf_lock is held by other cpu,
>> it'll lead to an infinity spin here. Isn't it?
>
> Yes, but we want to take the risk and print something out before the
> machine dies instead of waiting to get into printk-safe context first
> and maybe corrupt state.

Not all machine checks are fatal - it would be bad for us to go into an
infinite spin instead of executing the recovery code.

> Besides, there's work currently going on to make printk safe in atomic
> context so...

Good - we need this.

-Tony