sched_ext: Maintain an online cid mask in the scheduler arenagrafted

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 <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

1 files changed, 313 insertions, 0 deletions

diff --git a/drivers/usb/chipidea/debug.c b/drivers/usb/chipidea/debug.c
new file mode 100644
index 000000000..e72c43615
--- /dev/null
+++ b/drivers/usb/chipidea/debug.c
@@ -0,0 +1,313 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/types.h>
+#include <linux/spinlock.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+#include <linux/usb/ch9.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/phy.h>
+#include <linux/usb/otg.h>
+#include <linux/usb/otg-fsm.h>
+#include <linux/usb/chipidea.h>
+
+#include "ci.h"
+#include "udc.h"
+#include "bits.h"
+#include "otg.h"
+
+/*
+ * ci_device_show: prints information about device capabilities and status
+ */
+static int ci_device_show(struct seq_file *s, void *data)
+{
+	struct ci_hdrc *ci = s->private;
+	struct usb_gadget *gadget = &ci->gadget;
+
+	seq_printf(s, "speed             = %d\n", gadget->speed);
+	seq_printf(s, "max_speed         = %d\n", gadget->max_speed);
+	seq_printf(s, "is_otg            = %d\n", gadget->is_otg);
+	seq_printf(s, "is_a_peripheral   = %d\n", gadget->is_a_peripheral);
+	seq_printf(s, "b_hnp_enable      = %d\n", gadget->b_hnp_enable);
+	seq_printf(s, "a_hnp_support     = %d\n", gadget->a_hnp_support);
+	seq_printf(s, "a_alt_hnp_support = %d\n", gadget->a_alt_hnp_support);
+	seq_printf(s, "name              = %s\n",
+		   (gadget->name ? gadget->name : ""));
+
+	if (!ci->driver)
+		return 0;
+
+	seq_printf(s, "gadget function   = %s\n",
+		       (ci->driver->function ? ci->driver->function : ""));
+	seq_printf(s, "gadget max speed  = %d\n", ci->driver->max_speed);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(ci_device);
+
+/*
+ * ci_port_test_show: reads port test mode
+ */
+static int ci_port_test_show(struct seq_file *s, void *data)
+{
+	struct ci_hdrc *ci = s->private;
+	unsigned long flags;
+	unsigned mode;
+
+	pm_runtime_get_sync(ci->dev);
+	spin_lock_irqsave(&ci->lock, flags);
+	mode = hw_port_test_get(ci);
+	spin_unlock_irqrestore(&ci->lock, flags);
+	pm_runtime_put_sync(ci->dev);
+
+	seq_printf(s, "mode = %u\n", mode);
+
+	return 0;
+}
+
+/*
+ * ci_port_test_write: writes port test mode
+ */
+static ssize_t ci_port_test_write(struct file *file, const char __user *ubuf,
+				  size_t count, loff_t *ppos)
+{
+	struct seq_file *s = file->private_data;
+	struct ci_hdrc *ci = s->private;
+	unsigned long flags;
+	unsigned mode;
+	char buf[32];
+	int ret;
+
+	count = min_t(size_t, sizeof(buf) - 1, count);
+	if (copy_from_user(buf, ubuf, count))
+		return -EFAULT;
+
+	/* sscanf requires a zero terminated string */
+	buf[count] = '\0';
+
+	if (sscanf(buf, "%u", &mode) != 1)
+		return -EINVAL;
+
+	if (mode > 255)
+		return -EBADRQC;
+
+	pm_runtime_get_sync(ci->dev);
+	spin_lock_irqsave(&ci->lock, flags);
+	ret = hw_port_test_set(ci, mode);
+	spin_unlock_irqrestore(&ci->lock, flags);
+	pm_runtime_put_sync(ci->dev);
+
+	return ret ? ret : count;
+}
+
+static int ci_port_test_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, ci_port_test_show, inode->i_private);
+}
+
+static const struct file_operations ci_port_test_fops = {
+	.open		= ci_port_test_open,
+	.write		= ci_port_test_write,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+/*
+ * ci_qheads_show: DMA contents of all queue heads
+ */
+static int ci_qheads_show(struct seq_file *s, void *data)
+{
+	struct ci_hdrc *ci = s->private;
+	unsigned long flags;
+	unsigned i, j;
+
+	if (ci->role != CI_ROLE_GADGET) {
+		seq_printf(s, "not in gadget mode\n");
+		return 0;
+	}
+
+	spin_lock_irqsave(&ci->lock, flags);
+	for (i = 0; i < ci->hw_ep_max/2; i++) {
+		struct ci_hw_ep *hweprx = &ci->ci_hw_ep[i];
+		struct ci_hw_ep *hweptx =
+			&ci->ci_hw_ep[i + ci->hw_ep_max/2];
+		seq_printf(s, "EP=%02i: RX=%08X TX=%08X\n",
+			   i, (u32)hweprx->qh.dma, (u32)hweptx->qh.dma);
+		for (j = 0; j < (sizeof(struct ci_hw_qh)/sizeof(u32)); j++)
+			seq_printf(s, " %04X:    %08X    %08X\n", j,
+				   *((u32 *)hweprx->qh.ptr + j),
+				   *((u32 *)hweptx->qh.ptr + j));
+	}
+	spin_unlock_irqrestore(&ci->lock, flags);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(ci_qheads);
+
+/*
+ * ci_requests_show: DMA contents of all requests currently queued (all endpts)
+ */
+static int ci_requests_show(struct seq_file *s, void *data)
+{
+	struct ci_hdrc *ci = s->private;
+	unsigned long flags;
+	struct ci_hw_req *req = NULL;
+	struct td_node *node, *tmpnode;
+	unsigned i, j, qsize = sizeof(struct ci_hw_td)/sizeof(u32);
+
+	if (ci->role != CI_ROLE_GADGET) {
+		seq_printf(s, "not in gadget mode\n");
+		return 0;
+	}
+
+	spin_lock_irqsave(&ci->lock, flags);
+	for (i = 0; i < ci->hw_ep_max; i++)
+		list_for_each_entry(req, &ci->ci_hw_ep[i].qh.queue, queue) {
+			list_for_each_entry_safe(node, tmpnode, &req->tds, td) {
+				seq_printf(s, "EP=%02i: TD=%08X %s\n",
+					   i % (ci->hw_ep_max / 2),
+					   (u32)node->dma,
+					   ((i < ci->hw_ep_max/2) ?
+					   "RX" : "TX"));
+
+				for (j = 0; j < qsize; j++)
+					seq_printf(s, " %04X:    %08X\n", j,
+						   *((u32 *)node->ptr + j));
+			}
+		}
+	spin_unlock_irqrestore(&ci->lock, flags);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(ci_requests);
+
+static int ci_otg_show(struct seq_file *s, void *unused)
+{
+	struct ci_hdrc *ci = s->private;
+	struct otg_fsm *fsm;
+
+	if (!ci || !ci_otg_is_fsm_mode(ci))
+		return 0;
+
+	fsm = &ci->fsm;
+
+	/* ------ State ----- */
+	seq_printf(s, "OTG state: %s\n\n",
+			usb_otg_state_string(ci->otg.state));
+
+	/* ------ State Machine Variables ----- */
+	seq_printf(s, "a_bus_drop: %d\n", fsm->a_bus_drop);
+
+	seq_printf(s, "a_bus_req: %d\n", fsm->a_bus_req);
+
+	seq_printf(s, "a_srp_det: %d\n", fsm->a_srp_det);
+
+	seq_printf(s, "a_vbus_vld: %d\n", fsm->a_vbus_vld);
+
+	seq_printf(s, "b_conn: %d\n", fsm->b_conn);
+
+	seq_printf(s, "adp_change: %d\n", fsm->adp_change);
+
+	seq_printf(s, "power_up: %d\n", fsm->power_up);
+
+	seq_printf(s, "a_bus_resume: %d\n", fsm->a_bus_resume);
+
+	seq_printf(s, "a_bus_suspend: %d\n", fsm->a_bus_suspend);
+
+	seq_printf(s, "a_conn: %d\n", fsm->a_conn);
+
+	seq_printf(s, "b_bus_req: %d\n", fsm->b_bus_req);
+
+	seq_printf(s, "b_bus_suspend: %d\n", fsm->b_bus_suspend);
+
+	seq_printf(s, "b_se0_srp: %d\n", fsm->b_se0_srp);
+
+	seq_printf(s, "b_ssend_srp: %d\n", fsm->b_ssend_srp);
+
+	seq_printf(s, "b_sess_vld: %d\n", fsm->b_sess_vld);
+
+	seq_printf(s, "b_srp_done: %d\n", fsm->b_srp_done);
+
+	seq_printf(s, "drv_vbus: %d\n", fsm->drv_vbus);
+
+	seq_printf(s, "loc_conn: %d\n", fsm->loc_conn);
+
+	seq_printf(s, "loc_sof: %d\n", fsm->loc_sof);
+
+	seq_printf(s, "adp_prb: %d\n", fsm->adp_prb);
+
+	seq_printf(s, "id: %d\n", fsm->id);
+
+	seq_printf(s, "protocol: %d\n", fsm->protocol);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(ci_otg);
+
+static int ci_registers_show(struct seq_file *s, void *unused)
+{
+	struct ci_hdrc *ci = s->private;
+	u32 tmp_reg;
+
+	if (!ci || ci->in_lpm)
+		return -EPERM;
+
+	/* ------ Registers ----- */
+	tmp_reg = hw_read_intr_enable(ci);
+	seq_printf(s, "USBINTR reg: %08x\n", tmp_reg);
+
+	tmp_reg = hw_read_intr_status(ci);
+	seq_printf(s, "USBSTS reg: %08x\n", tmp_reg);
+
+	tmp_reg = hw_read(ci, OP_USBMODE, ~0);
+	seq_printf(s, "USBMODE reg: %08x\n", tmp_reg);
+
+	tmp_reg = hw_read(ci, OP_USBCMD, ~0);
+	seq_printf(s, "USBCMD reg: %08x\n", tmp_reg);
+
+	tmp_reg = hw_read(ci, OP_PORTSC, ~0);
+	seq_printf(s, "PORTSC reg: %08x\n", tmp_reg);
+
+	if (ci->is_otg) {
+		tmp_reg = hw_read_otgsc(ci, ~0);
+		seq_printf(s, "OTGSC reg: %08x\n", tmp_reg);
+	}
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(ci_registers);
+
+/**
+ * dbg_create_files: initializes the attribute interface
+ * @ci: device
+ *
+ * This function returns an error code
+ */
+void dbg_create_files(struct ci_hdrc *ci)
+{
+	struct dentry *dir;
+
+	dir = debugfs_create_dir(dev_name(ci->dev), usb_debug_root);
+
+	debugfs_create_file("device", S_IRUGO, dir, ci, &ci_device_fops);
+	debugfs_create_file("port_test", S_IRUGO | S_IWUSR, dir, ci, &ci_port_test_fops);
+	debugfs_create_file("qheads", S_IRUGO, dir, ci, &ci_qheads_fops);
+	debugfs_create_file("requests", S_IRUGO, dir, ci, &ci_requests_fops);
+
+	if (ci_otg_is_fsm_mode(ci))
+		debugfs_create_file("otg", S_IRUGO, dir, ci, &ci_otg_fops);
+
+	debugfs_create_file("registers", S_IRUGO, dir, ci, &ci_registers_fops);
+}
+
+/**
+ * dbg_remove_files: destroys the attribute interface
+ * @ci: device
+ */
+void dbg_remove_files(struct ci_hdrc *ci)
+{
+	debugfs_lookup_and_remove(dev_name(ci->dev), usb_debug_root);
+}