From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- include/net/llc_sap.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 include/net/llc_sap.h (limited to 'include/net/llc_sap.h') diff --git a/include/net/llc_sap.h b/include/net/llc_sap.h new file mode 100644 index 000000000..b259f5993 --- /dev/null +++ b/include/net/llc_sap.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef LLC_SAP_H +#define LLC_SAP_H + +#include + +/* + * Copyright (c) 1997 by Procom Technology,Inc. + * 2001-2003 by Arnaldo Carvalho de Melo + */ +struct llc_sap; +struct net_device; +struct sk_buff; +struct sock; + +void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb); +void llc_save_primitive(struct sock *sk, struct sk_buff *skb, + unsigned char prim); +struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev, + u8 type, u32 data_size); + +void llc_build_and_send_test_pkt(struct llc_sap *sap, struct sk_buff *skb, + unsigned char *dmac, unsigned char dsap); +void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb, + unsigned char *dmac, unsigned char dsap); +#endif /* LLC_SAP_H */ -- cgit v1.3.1