From: Saravana Kannan Date: Wed, 29 Sep 2021 19:05:49 +0000 (-0700) Subject: driver core: Reject pointless SYNC_STATE_ONLY device links X-Git-Tag: v5.15-rc6~11^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f729a592adb6760013c3e48622a5bf256b992452;p=thirdparty%2Fkernel%2Flinux.git 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. Fixes: 05ef983e0d65 ("driver core: Add device link support for SYNC_STATE_ONLY flag") Cc: stable Reported-by: Ulf Hansson Reviewed-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20210929190549.860541-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/base/core.c b/drivers/base/core.c index 15986cc2fe5e5..249da496581a0 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -687,7 +687,8 @@ struct device_link *device_link_add(struct device *consumer, { struct device_link *link; - if (!consumer || !supplier || flags & ~DL_ADD_VALID_FLAGS || + if (!consumer || !supplier || consumer == supplier || + flags & ~DL_ADD_VALID_FLAGS || (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) || (flags & DL_FLAG_SYNC_STATE_ONLY && (flags & ~DL_FLAG_INFERRED) != DL_FLAG_SYNC_STATE_ONLY) ||