Re: [PATCH] staging: zcache: fix serialization bug in zv stats

From: Seth Jennings
Date: Fri Dec 30 2011 - 12:35:52 EST

On 12/30/2011 11:02 AM, Dan Magenheimer wrote:
>> From: Seth Jennings [mailto:sjenning@xxxxxxxxxxxxxxxxxx]
>> Sent: Friday, December 30, 2011 9:42 AM
>> To: Greg Kroah-Hartman
>> Cc: Seth Jennings; Dan Magenheimer; Brian King; devel@xxxxxxxxxxxxxxxxxxxx; linux-
>> kernel@xxxxxxxxxxxxxxx
>> Subject: [PATCH] staging: zcache: fix serialization bug in zv stats
>> In a multithreaded workload, the zv_curr_dist_counts
>> and zv_cumul_dist_counts statistics are being corrupted
>> because the increments and decrements in zv_create
>> and zv_free are not atomic.
>> This patch converts these statistics and their corresponding
>> increments/decrements/reads to atomic operations.
>> Based on v3.2-rc7
>> Signed-off-by: Seth Jennings <sjenning@xxxxxxxxxxxxxxxxxx>
> I'm inclined to nack this change, at least unless inside an #ifdef DEBUG,

I guess I didn't respond to this suggestion. We could put #ifdef DEBUG
around the updates in zv_create and zv_free and around the two sysfs
*_show functions. Kinda messy though. I guess it might not matter
if we'll be re-evaluating this whole thing soon.

I'd just like to have it correct in mainline until then.


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