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, 112 insertions, 0 deletions

diff --git a/drivers/video/fbdev/sm712.h b/drivers/video/fbdev/sm712.h
new file mode 100644
index 000000000..83fe25fc6
--- /dev/null
+++ b/drivers/video/fbdev/sm712.h
@@ -0,0 +1,112 @@
+/*
+ * Silicon Motion SM712 frame buffer device
+ *
+ * Copyright (C) 2006 Silicon Motion Technology Corp.
+ * Authors:	Ge Wang, gewang@siliconmotion.com
+ *		Boyod boyod.yang@siliconmotion.com.cn
+ *
+ * Copyright (C) 2009 Lemote, Inc.
+ * Author: Wu Zhangjin, wuzhangjin@gmail.com
+ *
+ *  This file is subject to the terms and conditions of the GNU General Public
+ *  License. See the file COPYING in the main directory of this archive for
+ *  more details.
+ */
+
+#define FB_ACCEL_SMI_LYNX 88
+
+#define SCREEN_X_RES          1024
+#define SCREEN_Y_RES_PC       768
+#define SCREEN_Y_RES_NETBOOK  600
+#define SCREEN_BPP            16
+
+#define dac_reg	(0x3c8)
+#define dac_val	(0x3c9)
+
+extern void __iomem *smtc_regbaseaddress;
+#define smtc_mmiowb(dat, reg)	writeb(dat, smtc_regbaseaddress + reg)
+
+#define smtc_mmiorb(reg)	readb(smtc_regbaseaddress + reg)
+
+#define SIZE_SR00_SR04      (0x04 - 0x00 + 1)
+#define SIZE_SR10_SR24      (0x24 - 0x10 + 1)
+#define SIZE_SR30_SR75      (0x75 - 0x30 + 1)
+#define SIZE_SR80_SR93      (0x93 - 0x80 + 1)
+#define SIZE_SRA0_SRAF      (0xAF - 0xA0 + 1)
+#define SIZE_GR00_GR08      (0x08 - 0x00 + 1)
+#define SIZE_AR00_AR14      (0x14 - 0x00 + 1)
+#define SIZE_CR00_CR18      (0x18 - 0x00 + 1)
+#define SIZE_CR30_CR4D      (0x4D - 0x30 + 1)
+#define SIZE_CR90_CRA7      (0xA7 - 0x90 + 1)
+
+static inline void smtc_crtcw(int reg, int val)
+{
+	smtc_mmiowb(reg, 0x3d4);
+	smtc_mmiowb(val, 0x3d5);
+}
+
+static inline void smtc_grphw(int reg, int val)
+{
+	smtc_mmiowb(reg, 0x3ce);
+	smtc_mmiowb(val, 0x3cf);
+}
+
+static inline void smtc_attrw(int reg, int val)
+{
+	smtc_mmiorb(0x3da);
+	smtc_mmiowb(reg, 0x3c0);
+	smtc_mmiorb(0x3c1);
+	smtc_mmiowb(val, 0x3c0);
+}
+
+static inline void smtc_seqw(int reg, int val)
+{
+	smtc_mmiowb(reg, 0x3c4);
+	smtc_mmiowb(val, 0x3c5);
+}
+
+static inline unsigned int smtc_seqr(int reg)
+{
+	smtc_mmiowb(reg, 0x3c4);
+	return smtc_mmiorb(0x3c5);
+}
+
+/* The next structure holds all information relevant for a specific video mode.
+ */
+
+struct modeinit {
+	int mmsizex;
+	int mmsizey;
+	int bpp;
+	int hz;
+	unsigned char init_misc;
+	unsigned char init_sr00_sr04[SIZE_SR00_SR04];
+	unsigned char init_sr10_sr24[SIZE_SR10_SR24];
+	unsigned char init_sr30_sr75[SIZE_SR30_SR75];
+	unsigned char init_sr80_sr93[SIZE_SR80_SR93];
+	unsigned char init_sra0_sraf[SIZE_SRA0_SRAF];
+	unsigned char init_gr00_gr08[SIZE_GR00_GR08];
+	unsigned char init_ar00_ar14[SIZE_AR00_AR14];
+	unsigned char init_cr00_cr18[SIZE_CR00_CR18];
+	unsigned char init_cr30_cr4d[SIZE_CR30_CR4D];
+	unsigned char init_cr90_cra7[SIZE_CR90_CRA7];
+};
+
+#ifdef __BIG_ENDIAN
+#define pal_rgb(r, g, b, val)	(((r & 0xf800) >> 8) | \
+				((g & 0xe000) >> 13) | \
+				((g & 0x1c00) << 3) | \
+				((b & 0xf800) >> 3))
+#define big_addr		0x800000
+#define mmio_addr		0x00800000
+#define seqw17()		smtc_seqw(0x17, 0x30)
+#define big_pixel_depth(p, d)	{if (p == 24) {p = 32; d = 32; } }
+#define big_swap(p)		(((p & 0xff00ff00) >> 8) | ((p & 0x00ff00ff) << 8))
+#else
+#define pal_rgb(r, g, b, val)	val
+#define big_addr		0
+#define mmio_addr		0x00c00000
+#define seqw17()		do { } while (0)
+#define big_pixel_depth(p, d)	do { } while (0)
+#define big_swap(p)		p
+#endif