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

10 files changed, 18 insertions, 10 deletions

diff --git a/include/linux/dynamic_queue_limits.h b/include/linux/dynamic_queue_limits.h
index 99fc06f0afc1..407c2f281b64 100644
--- a/include/linux/dynamic_queue_limits.h
+++ b/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 */
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 25993b86ac5c..107cedd7019a 100644
--- a/include/linux/hrtimer.h
+++ b/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>
 
diff --git a/include/linux/ktime.h b/include/linux/ktime.h
index 42d2e6ac35f2..a12b5523cc18 100644
--- a/include/linux/ktime.h
+++ b/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;
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 39a35699d0d6..62a382d1845b 100644
--- a/include/linux/lockdep.h
+++ b/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;
diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index ae197cc00cc8..dcd185cbfe79 100644
--- a/include/linux/mutex.h
+++ b/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:
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9a9d8263962d..7c7a9499d7bc 100644
--- a/include/linux/sched.h
+++ b/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): */
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index a076f783aa36..962d9768945f 100644
--- a/include/linux/seqlock.h
+++ b/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>
 
diff --git a/include/linux/time.h b/include/linux/time.h
index 4c325bf44ce0..b142cb5f5a53 100644
--- a/include/linux/time.h
+++ b/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>
 
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 16c0ed6c50a7..219037f4c08d 100644
--- a/include/linux/videodev2.h
+++ b/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 */
diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
index d7554252404c..850424e5d030 100644
--- a/include/linux/ww_mutex.h
+++ b/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