Messages in this thread | | | Date | Wed, 2 May 2018 16:27:41 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH] mm: memory_hotplug: use put_device() if device_register fail |
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On Sat 28-04-18 11:05:44, arvindY wrote: > > > On Friday 27 April 2018 08:26 PM, Michal Hocko wrote: > > On Thu 26-04-18 21:12:09, Arvind Yadav wrote: > > > if device_register() returned an error. Always use put_device() > > > to give up the initialized reference and release allocated memory. > > Is this patch correct? The docummentation says > > * NOTE: _Never_ directly free @dev after calling this function, even > > * if it returned an error! Always use put_device() to give up your > > * reference instead. > > > > but we do not have _our_ reference in this path AFAICS. Maybe this is > > just a documentation issue? How have you tested this change btw.? > The document is correct. Here device_register() will initialize object by > making reference count as 1 and also increment reference count for device. > > device_register() { > device_initialize()->kobject_init()->kref_init() - initialize object( > reference count = 1). > device_add()->get_device() - increment reference count for device. > } > > If device_register() will fail then we have to release the object by making > reference count 0.
I am confused. If device_register intializes the reference to 1 then why it doesn't decrement it on a failure path and rather expects the caller to do that? The doc as I read it means that we should only drop a reference if we have our own one before calling device_register.
Or what do I miss here? -- Michal Hocko SUSE Labs
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