Messages in this thread | | | Date | Wed, 16 Apr 2014 11:17:49 -0400 | From | Tejun Heo <> | Subject | Re: [RFC PATCH v3] Use kernfs_break_active_protection() for device online store callbacks |
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Hello,
On Wed, Apr 16, 2014 at 09:41:40AM +0800, Li Zhong wrote: > > If so, that is > > an actually possible deadlock, no? > > Yes, but it seems to me that it is solved in commit 5e33bc41, which uses > lock_device_hotplug_sysfs() to return a restart syscall error if not > able to try lock the device_hotplug_lock. That also requires the device > removing code path to take the device_hotplug_lock.
But that patch only takes out device_hotplug_lock out of the dependency graph and does nothing for cpu_add_remove_lock. It seems to be that there still is a deadlock condition involving s_active and cpu_add_remove_lock. Am I missing something here?
Now that kernfs has a proper mechanism to deal with it, wouldn't it make more sense to replace 5e33bc41 with prper s_active protection breaking?
Thanks.
-- tejun
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