[PATCH] spinlock consolidation

This patch (written by me and also containing many suggestions of Arjan van
de Ven) does a major cleanup of the spinlock code.  It does the following
things:

 - consolidates and enhances the spinlock/rwlock debugging code

 - simplifies the asm/spinlock.h files

 - encapsulates the raw spinlock type and moves generic spinlock
   features (such as ->break_lock) into the generic code.

 - cleans up the spinlock code hierarchy to get rid of the spaghetti.

Most notably there's now only a single variant of the debugging code,
located in lib/spinlock_debug.c.  (previously we had one SMP debugging
variant per architecture, plus a separate generic one for UP builds)

Also, i've enhanced the rwlock debugging facility, it will now track
write-owners.  There is new spinlock-owner/CPU-tracking on SMP builds too.
All locks have lockup detection now, which will work for both soft and hard
spin/rwlock lockups.

The arch-level include files now only contain the minimally necessary
subset of the spinlock code - all the rest that can be generalized now
lives in the generic headers:

 include/asm-i386/spinlock_types.h       |   16
 include/asm-x86_64/spinlock_types.h     |   16

I have also split up the various spinlock variants into separate files,
making it easier to see which does what. The new layout is:

   SMP                         |  UP
   ----------------------------|-----------------------------------
   asm/spinlock_types_smp.h    |  linux/spinlock_types_up.h
   linux/spinlock_types.h      |  linux/spinlock_types.h
   asm/spinlock_smp.h          |  linux/spinlock_up.h
   linux/spinlock_api_smp.h    |  linux/spinlock_api_up.h
   linux/spinlock.h            |  linux/spinlock.h

/*
 * here's the role of the various spinlock/rwlock related include files:
 *
 * on SMP builds:
 *
 *  asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the
 *                        initializers
 *
 *  linux/spinlock_types.h:
 *                        defines the generic type and initializers
 *
 *  asm/spinlock.h:       contains the __raw_spin_*()/etc. lowlevel
 *                        implementations, mostly inline assembly code
 *
 *   (also included on UP-debug builds:)
 *
 *  linux/spinlock_api_smp.h:
 *                        contains the prototypes for the _spin_*() APIs.
 *
 *  linux/spinlock.h:     builds the final spin_*() APIs.
 *
 * on UP builds:
 *
 *  linux/spinlock_type_up.h:
 *                        contains the generic, simplified UP spinlock type.
 *                        (which is an empty structure on non-debug builds)
 *
 *  linux/spinlock_types.h:
 *                        defines the generic type and initializers
 *
 *  linux/spinlock_up.h:
 *                        contains the __raw_spin_*()/etc. version of UP
 *                        builds. (which are NOPs on non-debug, non-preempt
 *                        builds)
 *
 *   (included on UP-non-debug builds:)
 *
 *  linux/spinlock_api_up.h:
 *                        builds the _spin_*() APIs.
 *
 *  linux/spinlock.h:     builds the final spin_*() APIs.
 */

All SMP and UP architectures are converted by this patch.

arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via
crosscompilers.  m32r, mips, sh, sparc, have not been tested yet, but should
be mostly fine.

From: Grant Grundler <grundler@parisc-linux.org>

  Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU).
  Builds 32-bit SMP kernel (not booted or tested).  I did not try to build
  non-SMP kernels.  That should be trivial to fix up later if necessary.

  I converted bit ops atomic_hash lock to raw_spinlock_t.  Doing so avoids
  some ugly nesting of linux/*.h and asm/*.h files.  Those particular locks
  are well tested and contained entirely inside arch specific code.  I do NOT
  expect any new issues to arise with them.

 If someone does ever need to use debug/metrics with them, then they will
  need to unravel this hairball between spinlocks, atomic ops, and bit ops
  that exist only because parisc has exactly one atomic instruction: LDCW
  (load and clear word).

From: "Luck, Tony" <tony.luck@intel.com>

   ia64 fix

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjanv@infradead.org>
Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Cc: Matthew Wilcox <willy@debian.org>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se>
Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 14 insertions, 6 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 8d57a2f1226b..ff4dc02ce170 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -12,6 +12,7 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
 obj-$(CONFIG_FUTEX) += futex.o
 obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
 obj-$(CONFIG_SMP) += cpu.o spinlock.o
+obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
 obj-$(CONFIG_UID16) += uid16.o
 obj-$(CONFIG_MODULES) += module.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
diff --git a/kernel/sched.c b/kernel/sched.c
index 2632b812cf24..15db82116e19 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1511,6 +1511,10 @@ static inline void finish_task_switch(runqueue_t *rq, task_t *prev)
 	 *		Manfred Spraul <manfred@colorfullife.com>
 	 */
 	prev_task_flags = prev->flags;
+#ifdef CONFIG_DEBUG_SPINLOCK
+	/* this is a valid case when another task releases the spinlock */
+	rq->lock.owner = current;
+#endif
 	finish_arch_switch(prev);
 	finish_lock_switch(rq, prev);
 	if (mm)
diff --git a/kernel/spinlock.c b/kernel/spinlock.c
index 0c3f9d8bbe17..0375fcd5921d 100644
--- a/kernel/spinlock.c
+++ b/kernel/spinlock.c
@@ -3,7 +3,10 @@
  *
  * Author: Zwane Mwaikambo <zwane@fsmlabs.com>
  *
- * Copyright (2004) Ingo Molnar
+ * Copyright (2004, 2005) Ingo Molnar
+ *
+ * This file contains the spinlock/rwlock implementations for the
+ * SMP and the DEBUG_SPINLOCK cases. (UP-nondebug inlines them)
  */
 
 #include <linux/config.h>
@@ -17,12 +20,12 @@
  * Generic declaration of the raw read_trylock() function,
  * architectures are supposed to optimize this:
  */
-int __lockfunc generic_raw_read_trylock(rwlock_t *lock)
+int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock)
 {
-	_raw_read_lock(lock);
+	__raw_read_lock(lock);
 	return 1;
 }
-EXPORT_SYMBOL(generic_raw_read_trylock);
+EXPORT_SYMBOL(generic__raw_read_trylock);
 
 int __lockfunc _spin_trylock(spinlock_t *lock)
 {
@@ -57,7 +60,7 @@ int __lockfunc _write_trylock(rwlock_t *lock)
 }
 EXPORT_SYMBOL(_write_trylock);
 
-#ifndef CONFIG_PREEMPT
+#if !defined(CONFIG_PREEMPT) || !defined(CONFIG_SMP)
 
 void __lockfunc _read_lock(rwlock_t *lock)
 {
@@ -72,7 +75,7 @@ unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
 
 	local_irq_save(flags);
 	preempt_disable();
-	_raw_spin_lock_flags(lock, flags);
+	_raw_spin_lock_flags(lock, &flags);
 	return flags;
 }
 EXPORT_SYMBOL(_spin_lock_irqsave);