linux-kernel - Re: [PATCH 1/2] Drivers: hv: balloon: Fix a bug in the hot-add code

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Message-ID: <20130712201703.GB7729@decadent.org.uk>
Date:	Fri, 12 Jul 2013 21:17:03 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	"K. Y. Srinivasan" <kys@...rosoft.com>
Cc:	gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
	devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com,
	jasowang@...hat.com, Stable <stable@...r.kernel.org>
Subject: Re: [PATCH 1/2] Drivers: hv: balloon: Fix a bug in the hot-add code

On Fri, Jul 12, 2013 at 06:56:14AM -0700, K. Y. Srinivasan wrote:
> As we hot-add 128 MB chunks of memory, we wait to ensure that the memory
> is onlined before attempting to hot-add the next chunk. If the udev rule for
> memory hot-add is not executed within the allowed time, we would rollback the
> state and abort further hot-add. Since the hot-add has succeeded and the only
> failure is that the memory is not onlined within the allowed time, we should not
> be rolling back the state. Fix this bug.
[...]
>  		/*
>  		 * Wait for the memory block to be onlined.
>  		 */
> -		t = wait_for_completion_timeout(&dm_device.ol_waitevent, 5*HZ);
> -		if (t == 0) {
> -			pr_info("hot_add memory timedout\n");
> -			has->ha_end_pfn -= HA_CHUNK;
> -			has->covered_end_pfn -=  processed_pfn;
> -			break;
> -		}
> +		wait_for_completion_timeout(&dm_device.ol_waitevent, 5*HZ);
>  
>  	}
>  

Well now it might look like a bug that you don't test the result
of wait_for_completion_timeout().  Maybe update the comment to
explain why it's OK to continue anyway?

Ben.

-- 
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
                                                              - Albert Camus
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