UPSTREAM: driver core: Reject pointless SYNC_STATE_ONLY device links
SYNC_STATE_ONLY device links intentionally allow cycles because cyclic sync_state() dependencies are valid and necessary. However a SYNC_STATE_ONLY device link where the consumer and the supplier are the same device is pointless because the device link would be deleted as soon as the device probes (because it's also the consumer) and won't affect when the sync_state() callback is called. It's a waste of CPU cycles and memory to create this device link. So reject any attempts to create such a device link. Bug: 254441685 Fixes: 05ef983e0d65 ("driver core: Add device link support for SYNC_STATE_ONLY flag") Cc: stable <stable@vger.kernel.org> Reported-by:Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by:
Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by:
Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by:
Saravana Kannan <saravanak@google.com> Link: https://lore.kernel.org/r/20210929190549.860541-1-saravanak@google.com Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit f729a592adb6760013c3e48622a5bf256b992452) Signed-off-by:
Lee Jones <joneslee@google.com> Change-Id: I9eb0a3deba16944a698e6ac4a957776b539ab93a
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