From ff6461c1483420d0da542ff085dbd94e841afc1a Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Fri, 24 Jul 2026 14:07:56 -0700 Subject: [PATCH] net_shaper: add some notes on re-parenting Clarify the re-parenting expectations. Specifically that @delete on a queue removes it from the hierarchy which is a bit unusual in the overall API structure. IIRC the implicit delete behavior was introduced because otherwise it would not be possible to remove a queue from the hierarchy without changing at least one handle of the shapers. Normally "removal" is done by "adding" to the new parent, but "outside the hierarchy" does not have a parent we can point at. Link: https://patch.msgid.link/20260724210756.1553565-4-kuba@kernel.org Signed-off-by: Jakub Kicinski --- include/net/net_shaper.h | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/include/net/net_shaper.h b/include/net/net_shaper.h index c14eb87efe5e..05cb625b0fe5 100644 --- a/include/net/net_shaper.h +++ b/include/net/net_shaper.h @@ -107,7 +107,12 @@ struct net_shaper_ops { * The @leaves array's size is specified by @leaves_count. * * @node and @leaves may or may not already exist - * (see the "Implicit creation" note). + * (see the "Implicit creation" note). If @node already exists, + * the @leaves should be *added* to its children. In this case, + * the @leaves array only holds new/modified leaves, not the full list. + * + * Re-parenting @leaves is implemented by a @group call on a new parent. + * There's no explicit call to remove the children from the old parent. */ int (*group)(struct net_shaper_binding *binding, int leaves_count, const struct net_shaper *leaves, @@ -128,6 +133,13 @@ struct net_shaper_ops { * * Removes the shaper configuration as identified by the given @handle * on the device specified by @binding, restoring the default behavior. + * + * Note that a @delete call on a NET_SHAPER_SCOPE_QUEUE shaper also + * implicitly removes the associated queue from the scheduling + * hierarchy. The driver must take care of that step. + * @delete calls on NET_SHAPER_SCOPE_NODE should not require any + * implicit re-parenting in the driver as core will re-parent the leaves + * first, before deleting the SCOPE_NODE shaper. */ int (*delete)(struct net_shaper_binding *binding, const struct net_shaper_handle *handle,