Messages in this thread | | | Date | Wed, 23 Apr 2014 10:23:46 -0400 | From | Tejun Heo <> | Subject | Re: [RFC PATCH v5 2/2] Use kernfs_break_active_protection() for device online store callbacks |
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Hello, Rafael.
On Wed, Apr 23, 2014 at 12:21:33AM +0200, Rafael J. Wysocki wrote: > Can you please elaborate a bit?
Because it can get involved in larger locking dependency issues by joining dependency graphs of two otherwise largely disjoint subsystems. It has potential to create possible deadlocks which don't need to exist.
> It is there to protect hotplug operations involving multiple devices > (in different subsystems) from racing with each other. Why exactly > is it bad?
But why would different subsystems, say cpu and memory, use the same lock? Wouldn't those subsystems already have proper locking inside their own subsystems? Why add this additional global lock across multiple subsystems?
Thanks.
-- tejun
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