locking/seqlock, headers: Untangle the spaghetti monster

By using lockdep_assert_*() from seqlock.h, the spaghetti monster
attacked.

Attack back by reducing seqlock.h dependencies from two key high level headers:

 - <linux/seqlock.h>:               -Remove <linux/ww_mutex.h>
 - <linux/time.h>:                  -Remove <linux/seqlock.h>
 - <linux/sched.h>:                 +Add    <linux/seqlock.h>

The price was to add it to sched.h ...

Core header fallout, we add direct header dependencies instead of gaining them
parasitically from higher level headers:

 - <linux/dynamic_queue_limits.h>:  +Add <asm/bug.h>
 - <linux/hrtimer.h>:               +Add <linux/seqlock.h>
 - <linux/ktime.h>:                 +Add <asm/bug.h>
 - <linux/lockdep.h>:               +Add <linux/smp.h>
 - <linux/sched.h>:                 +Add <linux/seqlock.h>
 - <linux/videodev2.h>:             +Add <linux/kernel.h>

Arch headers fallout:

 - PARISC: <asm/timex.h>:           +Add <asm/special_insns.h>
 - SH:     <asm/io.h>:              +Add <asm/page.h>
 - SPARC:  <asm/timer_64.h>:        +Add <uapi/asm/asi.h>
 - SPARC:  <asm/vvar.h>:            +Add <asm/processor.h>, <asm/barrier.h>
                                    -Remove <linux/seqlock.h>
 - X86:    <asm/fixmap.h>:          +Add <asm/pgtable_types.h>
                                    -Remove <asm/acpi.h>

There's also a bunch of parasitic header dependency fallout in .c files, not listed
separately.

[ mingo: Extended the changelog, split up & fixed the original patch. ]

Co-developed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200804133438.GK2674@hirez.programming.kicks-ass.net

arch/sh/include/asm/io.h

@@ -17,6 +17,7 @@
 #include <asm/cache.h>
 #include <asm/addrspace.h>
 #include <asm/machvec.h>
+#include <asm/page.h>
 #include <linux/pgtable.h>
 #include <asm-generic/iomap.h>
 

arch/sh/kernel/machvec.c

@@ -15,6 +15,7 @@
 #include <asm/setup.h>
 #include <asm/io.h>
 #include <asm/irq.h>
+#include <asm/processor.h>
 
 #define MV_NAME_SIZE 32
 

arch/sparc/include/asm/timer_64.h

@@ -7,6 +7,7 @@
 #ifndef _SPARC64_TIMER_H
 #define _SPARC64_TIMER_H
 
+#include <uapi/asm/asi.h>
 #include <linux/types.h>
 #include <linux/init.h>
 

arch/sparc/include/asm/vvar.h

@@ -6,7 +6,8 @@
 #define _ASM_SPARC_VVAR_DATA_H
 
 #include <asm/clocksource.h>
-#include <linux/seqlock.h>
+#include <asm/processor.h>
+#include <asm/barrier.h>
 #include <linux/time.h>
 #include <linux/types.h>
 

arch/sparc/kernel/vdso.c

@@ -7,7 +7,6 @@
  *  a different vsyscall implementation for Linux/IA32 and for the name.
  */
 
-#include <linux/seqlock.h>
 #include <linux/time.h>
 #include <linux/timekeeper_internal.h>
 

arch/x86/include/asm/fixmap.h

@@ -26,9 +26,9 @@
 
 #ifndef __ASSEMBLY__
 #include <linux/kernel.h>
-#include <asm/acpi.h>
 #include <asm/apicdef.h>
 #include <asm/page.h>
+#include <asm/pgtable_types.h>
 #ifdef CONFIG_X86_32
 #include <linux/threads.h>
 #include <asm/kmap_types.h>

arch/x86/kernel/apic/apic_noop.c

@@ -10,6 +10,7 @@
  * like self-ipi, etc...
  */
 #include <linux/cpumask.h>
+#include <linux/thread_info.h>
 
 #include <asm/apic.h>
 

arch/x86/kernel/apic/hw_nmi.c

@@ -9,6 +9,7 @@
  *  Bits copied from original nmi.c file
  *
  */
+#include <linux/thread_info.h>
 #include <asm/apic.h>
 #include <asm/nmi.h>
 

arch/x86/kernel/apic/probe_64.c

@@ -8,6 +8,7 @@
  * Martin Bligh, Andi Kleen, James Bottomley, John Stultz, and
  * James Cleverdon.
  */
+#include <linux/thread_info.h>
 #include <asm/apic.h>
 
 #include "local.h"

arch/x86/kernel/cpu/amd.c

@@ -15,6 +15,7 @@
 #include <asm/cpu.h>
 #include <asm/spec-ctrl.h>
 #include <asm/smp.h>
+#include <asm/numa.h>
 #include <asm/pci-direct.h>
 #include <asm/delay.h>
 #include <asm/debugreg.h>

arch/x86/kernel/cpu/common.c

@@ -45,6 +45,7 @@
 #include <asm/mtrr.h>
 #include <asm/hwcap2.h>
 #include <linux/numa.h>
+#include <asm/numa.h>
 #include <asm/asm.h>
 #include <asm/bugs.h>
 #include <asm/cpu.h>

arch/x86/kernel/cpu/hygon.c

@@ -10,6 +10,7 @@
 
 #include <asm/cpu.h>
 #include <asm/smp.h>
+#include <asm/numa.h>
 #include <asm/cacheinfo.h>
 #include <asm/spec-ctrl.h>
 #include <asm/delay.h>

arch/x86/kernel/cpu/intel.c

@@ -23,6 +23,7 @@
 #include <asm/cmdline.h>
 #include <asm/traps.h>
 #include <asm/resctrl.h>
+#include <asm/numa.h>
 
 #ifdef CONFIG_X86_64
 #include <linux/topology.h>

arch/x86/kernel/jailhouse.c

@@ -14,6 +14,7 @@
 #include <linux/serial_8250.h>
 #include <asm/apic.h>
 #include <asm/io_apic.h>
+#include <asm/acpi.h>
 #include <asm/cpu.h>
 #include <asm/hypervisor.h>
 #include <asm/i8259.h>

arch/x86/kernel/tsc_msr.c

@@ -7,6 +7,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/thread_info.h>
 
 #include <asm/apic.h>
 #include <asm/cpu_device_id.h>

arch/x86/mm/init_32.c

@@ -52,6 +52,7 @@
 #include <asm/cpu_entry_area.h>
 #include <asm/init.h>
 #include <asm/pgtable_areas.h>
+#include <asm/numa.h>
 
 #include "mm_internal.h"
 

arch/x86/xen/apic.c

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/init.h>
+#include <linux/thread_info.h>
 
 #include <asm/x86_init.h>
 #include <asm/apic.h>

arch/x86/xen/smp_hvm.c

@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
+#include <linux/thread_info.h>
 #include <asm/smp.h>
 
 #include <xen/events.h>

arch/x86/xen/suspend_pv.c

@@ -1,11 +1,11 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/types.h>
 
-#include <asm/fixmap.h>
-
 #include <asm/xen/hypercall.h>
 #include <asm/xen/page.h>
 
+#include <asm/fixmap.h>
+
 #include "xen-ops.h"
 
 void xen_pv_pre_suspend(void)

include/linux/dynamic_queue_limits.h

@@ -38,6 +38,8 @@
 
 #ifdef __KERNEL__
 
+#include <asm/bug.h>
+
 struct dql {
 	/* Fields accessed in enqueue path (dql_queued) */
 	unsigned int	num_queued;		/* Total ever queued */

include/linux/hrtimer.h

@@ -17,6 +17,7 @@
 #include <linux/init.h>
 #include <linux/list.h>
 #include <linux/percpu.h>
+#include <linux/seqlock.h>
 #include <linux/timer.h>
 #include <linux/timerqueue.h>
 

include/linux/ktime.h

@@ -23,6 +23,7 @@
 
 #include <linux/time.h>
 #include <linux/jiffies.h>
+#include <asm/bug.h>
 
 /* Nanosecond scalar representation for kernel time values */
 typedef s64	ktime_t;

include/linux/lockdep.h

@@ -11,6 +11,7 @@
 #define __LINUX_LOCKDEP_H
 
 #include <linux/lockdep_types.h>
+#include <linux/smp.h>
 #include <asm/percpu.h>
 
 struct task_struct;

include/linux/mutex.h

@@ -65,6 +65,17 @@ struct mutex {
 #endif
 };
 
+struct ww_class;
+struct ww_acquire_ctx;
+
+struct ww_mutex {
+	struct mutex base;
+	struct ww_acquire_ctx *ctx;
+#ifdef CONFIG_DEBUG_MUTEXES
+	struct ww_class *ww_class;
+#endif
+};
+
 /*
  * This is the control structure for tasks blocked on mutex,
  * which resides on the blocked task's kernel stack:

include/linux/sched.h

@@ -31,6 +31,7 @@
 #include <linux/task_io_accounting.h>
 #include <linux/posix-timers.h>
 #include <linux/rseq.h>
+#include <linux/seqlock.h>
 #include <linux/kcsan.h>
 
 /* task_struct member predeclarations (sorted alphabetically): */

include/linux/seqlock.h

@@ -19,7 +19,6 @@
 #include <linux/mutex.h>
 #include <linux/preempt.h>
 #include <linux/spinlock.h>
-#include <linux/ww_mutex.h>
 
 #include <asm/processor.h>
 

include/linux/time.h

@@ -3,7 +3,6 @@
 #define _LINUX_TIME_H
 
 # include <linux/cache.h>
-# include <linux/seqlock.h>
 # include <linux/math64.h>
 # include <linux/time64.h>
 

include/linux/videodev2.h

@@ -57,6 +57,7 @@
 #define __LINUX_VIDEODEV2_H
 
 #include <linux/time.h>     /* need struct timeval */
+#include <linux/kernel.h>
 #include <uapi/linux/videodev2.h>
 
 #endif /* __LINUX_VIDEODEV2_H */

include/linux/ww_mutex.h

@@ -48,14 +48,6 @@ struct ww_acquire_ctx {
 #endif
 };
 
-struct ww_mutex {
-	struct mutex base;
-	struct ww_acquire_ctx *ctx;
-#ifdef CONFIG_DEBUG_MUTEXES
-	struct ww_class *ww_class;
-#endif
-};
-
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 # define __WW_CLASS_MUTEX_INITIALIZER(lockname, class) \
 		, .ww_class = class