Messages in this thread | | | Date | Thu, 7 Feb 2019 20:03:26 +0100 | From | Lukas Wunner <> | Subject | Re: [PATCH v2 2/9] driver core: Avoid careless re-use of existing device links |
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Sorry, late to the party.
On Fri, Feb 01, 2019 at 01:46:54AM +0100, Rafael J. Wysocki wrote: > After commit ead18c23c263 ("driver core: Introduce device links > reference counting"), if there is a link between the given supplier > and the given consumer already, device_link_add() will refcount it > and return it unconditionally. However, if the flags passed to > it on the second (or any subsequent) attempt to create a device > link between the same consumer-supplier pair are not compatible with > the existing link's flags, that is incorrect.
Prior to ead18c23c263, a second invocation of device_link_add() also returned the existing device link without checking for incompatible flags. Hence this issue was not introduced by ead18c23c263, but rather by 9ed9895370ae ("driver core: Functional dependencies tracking support"), i.e. it was present all along. (Unless I'm missing something.)
> Moreover, if the DL_FLAG_AUTOREMOVE_CONSUMER flag is passed to > device_link_add(), its caller will expect its reference to the link > to be dropped automatically on consumer driver removal, which will > not happen if that flag is not set in the link's flags (and > analogously for DL_FLAG_AUTOREMOVE_SUPPLIER). For this reason, make > device_link_add() update the existing link's flags accordingly > before returning it to the caller.
Same here.
> Fixes: ead18c23c263 ("driver core: Introduce device links reference counting")
Should rather be Fixes: 9ed9895370ae ("driver core: Functional dependencies tracking support")
(Again, unless I'm missing something.)
Thanks,
Lukas
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