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 --- samples/rpmsg/Makefile | 2 + samples/rpmsg/rpmsg_client_sample.c | 96 +++++++++++++++++++++++++++++++++++++ 2 files changed, 98 insertions(+) create mode 100644 samples/rpmsg/Makefile create mode 100644 samples/rpmsg/rpmsg_client_sample.c (limited to 'samples/rpmsg') diff --git a/samples/rpmsg/Makefile b/samples/rpmsg/Makefile new file mode 100644 index 000000000..ddf9a5d13 --- /dev/null +++ b/samples/rpmsg/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_SAMPLE_RPMSG_CLIENT) += rpmsg_client_sample.o diff --git a/samples/rpmsg/rpmsg_client_sample.c b/samples/rpmsg/rpmsg_client_sample.c new file mode 100644 index 000000000..ae5081662 --- /dev/null +++ b/samples/rpmsg/rpmsg_client_sample.c @@ -0,0 +1,96 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Remote processor messaging - sample client driver + * + * Copyright (C) 2011 Texas Instruments, Inc. + * Copyright (C) 2011 Google, Inc. + * + * Ohad Ben-Cohen + * Brian Swetland + */ + +#include +#include +#include + +#define MSG "hello world!" + +static int count = 100; +module_param(count, int, 0644); + +struct instance_data { + int rx_count; +}; + +static int rpmsg_sample_cb(struct rpmsg_device *rpdev, void *data, int len, + void *priv, u32 src) +{ + int ret; + struct instance_data *idata = dev_get_drvdata(&rpdev->dev); + + dev_info(&rpdev->dev, "incoming msg %d (src: 0x%x)\n", + ++idata->rx_count, src); + + print_hex_dump_debug(__func__, DUMP_PREFIX_NONE, 16, 1, data, len, + true); + + /* samples should not live forever */ + if (idata->rx_count >= count) { + dev_info(&rpdev->dev, "goodbye!\n"); + return 0; + } + + /* send a new message now */ + ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG)); + if (ret) + dev_err(&rpdev->dev, "rpmsg_send failed: %d\n", ret); + + return 0; +} + +static int rpmsg_sample_probe(struct rpmsg_device *rpdev) +{ + int ret; + struct instance_data *idata; + + dev_info(&rpdev->dev, "new channel: 0x%x -> 0x%x!\n", + rpdev->src, rpdev->dst); + + idata = devm_kzalloc(&rpdev->dev, sizeof(*idata), GFP_KERNEL); + if (!idata) + return -ENOMEM; + + dev_set_drvdata(&rpdev->dev, idata); + + /* send a message to our remote processor */ + ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG)); + if (ret) { + dev_err(&rpdev->dev, "rpmsg_send failed: %d\n", ret); + return ret; + } + + return 0; +} + +static void rpmsg_sample_remove(struct rpmsg_device *rpdev) +{ + dev_info(&rpdev->dev, "rpmsg sample client driver is removed\n"); +} + +static struct rpmsg_device_id rpmsg_driver_sample_id_table[] = { + { .name = "rpmsg-client-sample" }, + { }, +}; +MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_sample_id_table); + +static struct rpmsg_driver rpmsg_sample_client = { + .drv.name = KBUILD_MODNAME, + .id_table = rpmsg_driver_sample_id_table, + .probe = rpmsg_sample_probe, + .callback = rpmsg_sample_cb, + .remove = rpmsg_sample_remove, +}; +module_rpmsg_driver(rpmsg_sample_client); + +MODULE_DESCRIPTION("Remote processor messaging sample client driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1