linux-kernel - Re: [PATCH] [PATCH/RESEND] driver core: remove polling for driver_probe

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Message-ID: <20090220073345.501247f7@infradead.org>
Date:	Fri, 20 Feb 2009 07:33:45 -0800
From:	Arjan van de Ven <arjan@...radead.org>
To:	tom.leiming@...il.com
Cc:	kay.sievers@...y.org, greg@...ah.com, cornelia.huck@...ibm.com,
	linux-kernel@...r.kernel.org, Ming Lei <tom.leiming@...il.com>
Subject: Re: [PATCH] [PATCH/RESEND] driver core: remove polling for
 driver_probe_done(v4)

On Fri, 20 Feb 2009 22:17:27 +0800
tom.leiming@...il.com wrote:

> From: Ming Lei <tom.leiming@...il.com>
> 
> This patch adds a function : driver_wait_probe_done,
> which waits on condition of probing done to replace
> polling for driver_probe_done in fs initialization.
> 
> There is no better way to avoid polling for
> driver_probe_done _and_ existence of the root device,
> so we does not replace the driver_probe_done with
> driver_wait_probe_done in such special case.
> 
> Removing polling in fs initialization may lead to
> a faster boot.
> 
> This patch is against the latest linux-next tree.

you broke it i this revision though

> -int wait_for_device_probe(void)
> +void driver_wait_probe_done(void)
>  {
> -	/* wait for the known devices to complete their probing */
> -	while (driver_probe_done() != 0)
> -		msleep(100);
> -	async_synchronize_full();
> -	return 0;
> +	pr_debug("%s: probe_count = %d\n", __func__,
> +		 atomic_read(&probe_count));
> +	wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);


You lost the async_synchronize_full()!


> -	wait_for_device_probe();
> +	driver_wait_probe_done();

I also don't understand why you rename the function..
wait_for_device_probe() is not a bad name ;)
Sounds like a gratuitous change to me.


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
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