Messages in this thread | | | Date | Wed, 20 Jul 2011 23:46:03 +0400 | From | Vasiliy Kulikov <> | Subject | Re: [PATCH 2/2] taskstats: add_del_listener() should ignore !valid listener's |
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On Wed, Jul 20, 2011 at 21:00 +0200, Oleg Nesterov wrote: > When send_cpu_listeners() finds the orphaned listener it marks > it as !valid and drops listeners->sem. Before it takes this sem > for wrinting, s->pid can be reused and add_del_listener() can > wrongly try to re-use this entry. > > Change add_del_listener() to check ->valid = T.
I think the current logic is wrong. If s was claimed is invalid, it then points to a dead task, it is unknown when it died. As the same pid can be reused by a new process BEFORE add_del_listener(), it is unknown whether ->pid points to the actual owner task.
Rather than optimizing the wrong algorithm it's better to change the processes keeping way.
Thanks,
-- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments
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