[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>

1 files changed, 80 insertions, 0 deletions

diff --git a/include/linux/spinlock_api_up.h b/include/linux/spinlock_api_up.h
new file mode 100644
index 000000000000..cd81cee566f4
--- /dev/null
+++ b/include/linux/spinlock_api_up.h
@@ -0,0 +1,80 @@
+#ifndef __LINUX_SPINLOCK_API_UP_H
+#define __LINUX_SPINLOCK_API_UP_H
+
+#ifndef __LINUX_SPINLOCK_H
+# error "please don't include this file directly"
+#endif
+
+/*
+ * include/linux/spinlock_api_up.h
+ *
+ * spinlock API implementation on UP-nondebug (inlined implementation)
+ *
+ * portions Copyright 2005, Red Hat, Inc., Ingo Molnar
+ * Released under the General Public License (GPL).
+ */
+
+#define in_lock_functions(ADDR)         0
+
+#define assert_spin_locked(lock)        do { (void)(lock); } while (0)
+
+/*
+ * In the UP-nondebug case there's no real locking going on, so the
+ * only thing we have to do is to keep the preempt counts and irq
+ * flags straight, to supress compiler warnings of unused lock
+ * variables, and to add the proper checker annotations:
+ */
+#define __LOCK(lock) \
+  do { preempt_disable(); __acquire(lock); (void)(lock); } while (0)
+
+#define __LOCK_BH(lock) \
+  do { local_bh_disable(); __LOCK(lock); } while (0)
+
+#define __LOCK_IRQ(lock) \
+  do { local_irq_disable(); __LOCK(lock); } while (0)
+
+#define __LOCK_IRQSAVE(lock, flags) \
+  do { local_irq_save(flags); __LOCK(lock); } while (0)
+
+#define __UNLOCK(lock) \
+  do { preempt_enable(); __release(lock); (void)(lock); } while (0)
+
+#define __UNLOCK_BH(lock) \
+  do { preempt_enable_no_resched(); local_bh_enable(); __release(lock); (void)(lock); } while (0)
+
+#define __UNLOCK_IRQ(lock) \
+  do { local_irq_enable(); __UNLOCK(lock); } while (0)
+
+#define __UNLOCK_IRQRESTORE(lock, flags) \
+  do { local_irq_restore(flags); __UNLOCK(lock); } while (0)
+
+#define _spin_lock(lock)                        __LOCK(lock)
+#define _read_lock(lock)                        __LOCK(lock)
+#define _write_lock(lock)                       __LOCK(lock)
+#define _spin_lock_bh(lock)                     __LOCK_BH(lock)
+#define _read_lock_bh(lock)                     __LOCK_BH(lock)
+#define _write_lock_bh(lock)                    __LOCK_BH(lock)
+#define _spin_lock_irq(lock)                    __LOCK_IRQ(lock)
+#define _read_lock_irq(lock)                    __LOCK_IRQ(lock)
+#define _write_lock_irq(lock)                   __LOCK_IRQ(lock)
+#define _spin_lock_irqsave(lock, flags)         __LOCK_IRQSAVE(lock, flags)
+#define _read_lock_irqsave(lock, flags)         __LOCK_IRQSAVE(lock, flags)
+#define _write_lock_irqsave(lock, flags)        __LOCK_IRQSAVE(lock, flags)
+#define _spin_trylock(lock)                     ({ __LOCK(lock); 1; })
+#define _read_trylock(lock)                     ({ __LOCK(lock); 1; })
+#define _write_trylock(lock)                    ({ __LOCK(lock); 1; })
+#define _spin_trylock_bh(lock)                  ({ __LOCK_BH(lock); 1; })
+#define _spin_unlock(lock)                      __UNLOCK(lock)
+#define _read_unlock(lock)                      __UNLOCK(lock)
+#define _write_unlock(lock)                     __UNLOCK(lock)
+#define _spin_unlock_bh(lock)                   __UNLOCK_BH(lock)
+#define _write_unlock_bh(lock)                  __UNLOCK_BH(lock)
+#define _read_unlock_bh(lock)                   __UNLOCK_BH(lock)
+#define _spin_unlock_irq(lock)                  __UNLOCK_IRQ(lock)
+#define _read_unlock_irq(lock)                  __UNLOCK_IRQ(lock)
+#define _write_unlock_irq(lock)                 __UNLOCK_IRQ(lock)
+#define _spin_unlock_irqrestore(lock, flags)    __UNLOCK_IRQRESTORE(lock, flags)
+#define _read_unlock_irqrestore(lock, flags)    __UNLOCK_IRQRESTORE(lock, flags)
+#define _write_unlock_irqrestore(lock, flags)   __UNLOCK_IRQRESTORE(lock, flags)
+
+#endif /* __LINUX_SPINLOCK_API_UP_H */