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, 250 insertions, 0 deletions

diff --git a/drivers/video/fbdev/sunxvr2500.c b/drivers/video/fbdev/sunxvr2500.c
new file mode 100644
index 000000000..b7587ff4d
--- /dev/null
+++ b/drivers/video/fbdev/sunxvr2500.c
@@ -0,0 +1,250 @@
+/* sunxvr2500.c: Sun 3DLABS XVR-2500 et al. fb driver for sparc64 systems
+ *
+ * License: GPL
+ *
+ * Copyright (C) 2007 David S. Miller (davem@davemloft.net)
+ */
+
+#include <linux/aperture.h>
+#include <linux/kernel.h>
+#include <linux/fb.h>
+#include <linux/pci.h>
+#include <linux/init.h>
+#include <linux/of.h>
+
+#include <asm/io.h>
+
+struct s3d_info {
+	struct fb_info		*info;
+	struct pci_dev		*pdev;
+
+	char __iomem		*fb_base;
+	unsigned long		fb_base_phys;
+
+	struct device_node	*of_node;
+
+	unsigned int		width;
+	unsigned int		height;
+	unsigned int		depth;
+	unsigned int		fb_size;
+
+	u32			pseudo_palette[16];
+};
+
+static int s3d_get_props(struct s3d_info *sp)
+{
+	sp->width = of_getintprop_default(sp->of_node, "width", 0);
+	sp->height = of_getintprop_default(sp->of_node, "height", 0);
+	sp->depth = of_getintprop_default(sp->of_node, "depth", 8);
+
+	if (!sp->width || !sp->height) {
+		pci_err(sp->pdev, "Critical properties missing\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int s3d_setcolreg(unsigned regno,
+			 unsigned red, unsigned green, unsigned blue,
+			 unsigned transp, struct fb_info *info)
+{
+	u32 value;
+
+	if (regno < 16) {
+		red >>= 8;
+		green >>= 8;
+		blue >>= 8;
+
+		value = (blue << 24) | (green << 16) | (red << 8);
+		((u32 *)info->pseudo_palette)[regno] = value;
+	}
+
+	return 0;
+}
+
+static const struct fb_ops s3d_ops = {
+	.owner			= THIS_MODULE,
+	FB_DEFAULT_IOMEM_OPS,
+	.fb_setcolreg		= s3d_setcolreg,
+};
+
+static int s3d_set_fbinfo(struct s3d_info *sp)
+{
+	struct fb_info *info = sp->info;
+	struct fb_var_screeninfo *var = &info->var;
+
+	info->fbops = &s3d_ops;
+	info->screen_base = sp->fb_base;
+	info->screen_size = sp->fb_size;
+
+	info->pseudo_palette = sp->pseudo_palette;
+
+	/* Fill fix common fields */
+	strscpy(info->fix.id, "s3d", sizeof(info->fix.id));
+        info->fix.smem_start = sp->fb_base_phys;
+        info->fix.smem_len = sp->fb_size;
+        info->fix.type = FB_TYPE_PACKED_PIXELS;
+	if (sp->depth == 32 || sp->depth == 24)
+		info->fix.visual = FB_VISUAL_TRUECOLOR;
+	else
+		info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
+
+	var->xres = sp->width;
+	var->yres = sp->height;
+	var->xres_virtual = var->xres;
+	var->yres_virtual = var->yres;
+	var->bits_per_pixel = sp->depth;
+
+	var->red.offset = 8;
+	var->red.length = 8;
+	var->green.offset = 16;
+	var->green.length = 8;
+	var->blue.offset = 24;
+	var->blue.length = 8;
+	var->transp.offset = 0;
+	var->transp.length = 0;
+
+	if (fb_alloc_cmap(&info->cmap, 256, 0)) {
+		pci_err(sp->pdev, "Cannot allocate color map\n");
+		return -ENOMEM;
+	}
+
+        return 0;
+}
+
+static int s3d_pci_register(struct pci_dev *pdev,
+			    const struct pci_device_id *ent)
+{
+	struct fb_info *info;
+	struct s3d_info *sp;
+	int err;
+
+	err = aperture_remove_conflicting_pci_devices(pdev, "s3dfb");
+	if (err)
+		return err;
+
+	err = pci_enable_device(pdev);
+	if (err < 0) {
+		pci_err(pdev, "Cannot enable PCI device\n");
+		goto err_out;
+	}
+
+	info = framebuffer_alloc(sizeof(struct s3d_info), &pdev->dev);
+	if (!info) {
+		err = -ENOMEM;
+		goto err_disable;
+	}
+
+	sp = info->par;
+	sp->info = info;
+	sp->pdev = pdev;
+	sp->of_node = pci_device_to_OF_node(pdev);
+	if (!sp->of_node) {
+		pci_err(pdev, "Cannot find OF node\n");
+		err = -ENODEV;
+		goto err_release_fb;
+	}
+
+	sp->fb_base_phys = pci_resource_start (pdev, 1);
+
+	err = pci_request_region(pdev, 1, "s3d framebuffer");
+	if (err < 0) {
+		pci_err(pdev, "Cannot request region 1\n");
+		goto err_release_fb;
+	}
+
+	err = s3d_get_props(sp);
+	if (err)
+		goto err_release_pci;
+
+	/* XXX 'linebytes' is often wrong, it is equal to the width
+	 * XXX with depth of 32 on my XVR-2500 which is clearly not
+	 * XXX right.  So we don't try to use it.
+	 */
+	switch (sp->depth) {
+	case 8:
+		info->fix.line_length = sp->width;
+		break;
+	case 16:
+		info->fix.line_length = sp->width * 2;
+		break;
+	case 24:
+		info->fix.line_length = sp->width * 3;
+		break;
+	case 32:
+		info->fix.line_length = sp->width * 4;
+		break;
+	}
+	sp->fb_size = info->fix.line_length * sp->height;
+
+	sp->fb_base = ioremap(sp->fb_base_phys, sp->fb_size);
+	if (!sp->fb_base) {
+		err = -ENOMEM;
+		goto err_release_pci;
+	}
+
+	err = s3d_set_fbinfo(sp);
+	if (err)
+		goto err_unmap_fb;
+
+	pci_set_drvdata(pdev, info);
+
+	pci_info(pdev, "Found device\n");
+
+	err = register_framebuffer(info);
+	if (err < 0) {
+		pci_err(pdev, "Could not register framebuffer\n");
+		goto err_unmap_fb;
+	}
+
+	return 0;
+
+err_unmap_fb:
+	iounmap(sp->fb_base);
+
+err_release_pci:
+	pci_release_region(pdev, 1);
+
+err_release_fb:
+        framebuffer_release(info);
+
+err_disable:
+	pci_disable_device(pdev);
+
+err_out:
+	return err;
+}
+
+static const struct pci_device_id s3d_pci_table[] = {
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x002c),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x002d),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x002e),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x002f),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x0030),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x0031),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x0032),	},
+	{	PCI_DEVICE(PCI_VENDOR_ID_3DLABS, 0x0033),	},
+	{ 0, }
+};
+
+static struct pci_driver s3d_driver = {
+	.driver = {
+		.suppress_bind_attrs = true,
+	},
+	.name		= "s3d",
+	.id_table	= s3d_pci_table,
+	.probe		= s3d_pci_register,
+};
+
+static int __init s3d_init(void)
+{
+	if (fb_modesetting_disabled("s3d"))
+		return -ENODEV;
+
+	if (fb_get_options("s3d", NULL))
+		return -ENODEV;
+
+	return pci_register_driver(&s3d_driver);
+}
+device_initcall(s3d_init);