linux-kernel - Re: [v3 PATCH 1/1] init: fix race between rootfs mount and firmware loading

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Message-ID: <20140918174127.GB340@redhat.com>
Date:	Thu, 18 Sep 2014 19:41:27 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Roman Pen <r.peniaev@...il.com>
Cc:	Ming Lei <ming.lei@...onical.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [v3 PATCH 1/1] init: fix race between rootfs mount and
	firmware loading

On 09/18, Roman Pen wrote:
>
> +void wait_for_rootfs(void)
> +{
> +	/* Avoid waiting for ourselves */
> +	if (WARN_ON(is_global_init(current)))
> +		return;
> +	else
> +		wait_event(rootfs_waitq, rootfs_mounted);
> +}

Ah, wait, the is_global_init() check doesn't look right in any case.

What if /sbin/init does sys_init_module() and this module does
request_firmware() ?

I think we should only warn if init is going to wait,

	/* Avoid waiting for ourselves */
	if (rootfs_mounted || WARN_ON(is_global_init(current)))
		return;

	__wait_event(rootfs_waitq, rootfs_mounted);


> +EXPORT_SYMBOL(wait_for_rootfs);

Why?

Oleg.

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