[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>

2 files changed, 0 insertions, 181 deletions

diff --git a/arch/alpha/kernel/alpha_ksyms.c b/arch/alpha/kernel/alpha_ksyms.c
index fc5ef90..24ae9a3 100644
--- a/arch/alpha/kernel/alpha_ksyms.c
+++ b/arch/alpha/kernel/alpha_ksyms.c
@@ -185,15 +185,6 @@ EXPORT_SYMBOL(smp_num_cpus);
 EXPORT_SYMBOL(smp_call_function);
 EXPORT_SYMBOL(smp_call_function_on_cpu);
 EXPORT_SYMBOL(_atomic_dec_and_lock);
-#ifdef CONFIG_DEBUG_SPINLOCK
-EXPORT_SYMBOL(_raw_spin_unlock);
-EXPORT_SYMBOL(debug_spin_lock);
-EXPORT_SYMBOL(debug_spin_trylock);
-#endif
-#ifdef CONFIG_DEBUG_RWLOCK
-EXPORT_SYMBOL(_raw_write_lock);
-EXPORT_SYMBOL(_raw_read_lock);
-#endif
 EXPORT_SYMBOL(cpu_present_mask);
 #endif /* CONFIG_SMP */
 
diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index e211aa7..da0be34 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -989,175 +989,3 @@ flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
 
 	preempt_enable();
 }
-
-#ifdef CONFIG_DEBUG_SPINLOCK
-void
-_raw_spin_unlock(spinlock_t * lock)
-{
-	mb();
-	lock->lock = 0;
-
-	lock->on_cpu = -1;
-	lock->previous = NULL;
-	lock->task = NULL;
-	lock->base_file = "none";
-	lock->line_no = 0;
-}
-
-void
-debug_spin_lock(spinlock_t * lock, const char *base_file, int line_no)
-{
-	long tmp;
-	long stuck;
-	void *inline_pc = __builtin_return_address(0);
-	unsigned long started = jiffies;
-	int printed = 0;
-	int cpu = smp_processor_id();
-
-	stuck = 1L << 30;
- try_again:
-
-	/* Use sub-sections to put the actual loop at the end
-	   of this object file's text section so as to perfect
-	   branch prediction.  */
-	__asm__ __volatile__(
-	"1:	ldl_l	%0,%1\n"
-	"	subq	%2,1,%2\n"
-	"	blbs	%0,2f\n"
-	"	or	%0,1,%0\n"
-	"	stl_c	%0,%1\n"
-	"	beq	%0,3f\n"
-	"4:	mb\n"
-	".subsection 2\n"
-	"2:	ldl	%0,%1\n"
-	"	subq	%2,1,%2\n"
-	"3:	blt	%2,4b\n"
-	"	blbs	%0,2b\n"
-	"	br	1b\n"
-	".previous"
-	: "=r" (tmp), "=m" (lock->lock), "=r" (stuck)
-	: "m" (lock->lock), "2" (stuck) : "memory");
-
-	if (stuck < 0) {
-		printk(KERN_WARNING
-		       "%s:%d spinlock stuck in %s at %p(%d)"
-		       " owner %s at %p(%d) %s:%d\n",
-		       base_file, line_no,
-		       current->comm, inline_pc, cpu,
-		       lock->task->comm, lock->previous,
-		       lock->on_cpu, lock->base_file, lock->line_no);
-		stuck = 1L << 36;
-		printed = 1;
-		goto try_again;
-	}
-
-	/* Exiting.  Got the lock.  */
-	lock->on_cpu = cpu;
-	lock->previous = inline_pc;
-	lock->task = current;
-	lock->base_file = base_file;
-	lock->line_no = line_no;
-
-	if (printed) {
-		printk(KERN_WARNING
-		       "%s:%d spinlock grabbed in %s at %p(%d) %ld ticks\n",
-		       base_file, line_no, current->comm, inline_pc,
-		       cpu, jiffies - started);
-	}
-}
-
-int
-debug_spin_trylock(spinlock_t * lock, const char *base_file, int line_no)
-{
-	int ret;
-	if ((ret = !test_and_set_bit(0, lock))) {
-		lock->on_cpu = smp_processor_id();
-		lock->previous = __builtin_return_address(0);
-		lock->task = current;
-	} else {
-		lock->base_file = base_file;
-		lock->line_no = line_no;
-	}
-	return ret;
-}
-#endif /* CONFIG_DEBUG_SPINLOCK */
-
-#ifdef CONFIG_DEBUG_RWLOCK
-void _raw_write_lock(rwlock_t * lock)
-{
-	long regx, regy;
-	int stuck_lock, stuck_reader;
-	void *inline_pc = __builtin_return_address(0);
-
- try_again:
-
-	stuck_lock = 1<<30;
-	stuck_reader = 1<<30;
-
-	__asm__ __volatile__(
-	"1:	ldl_l	%1,%0\n"
-	"	blbs	%1,6f\n"
-	"	blt	%1,8f\n"
-	"	mov	1,%1\n"
-	"	stl_c	%1,%0\n"
-	"	beq	%1,6f\n"
-	"4:	mb\n"
-	".subsection 2\n"
-	"6:	blt	%3,4b	# debug\n"
-	"	subl	%3,1,%3	# debug\n"
-	"	ldl	%1,%0\n"
-	"	blbs	%1,6b\n"
-	"8:	blt	%4,4b	# debug\n"
-	"	subl	%4,1,%4	# debug\n"
-	"	ldl	%1,%0\n"
-	"	blt	%1,8b\n"
-	"	br	1b\n"
-	".previous"
-	: "=m" (*(volatile int *)lock), "=&r" (regx), "=&r" (regy),
-	  "=&r" (stuck_lock), "=&r" (stuck_reader)
-	: "m" (*(volatile int *)lock), "3" (stuck_lock), "4" (stuck_reader) : "memory");
-
-	if (stuck_lock < 0) {
-		printk(KERN_WARNING "write_lock stuck at %p\n", inline_pc);
-		goto try_again;
-	}
-	if (stuck_reader < 0) {
-		printk(KERN_WARNING "write_lock stuck on readers at %p\n",
-		       inline_pc);
-		goto try_again;
-	}
-}
-
-void _raw_read_lock(rwlock_t * lock)
-{
-	long regx;
-	int stuck_lock;
-	void *inline_pc = __builtin_return_address(0);
-
- try_again:
-
-	stuck_lock = 1<<30;
-
-	__asm__ __volatile__(
-	"1:	ldl_l	%1,%0;"
-	"	blbs	%1,6f;"
-	"	subl	%1,2,%1;"
-	"	stl_c	%1,%0;"
-	"	beq	%1,6f;"
-	"4:	mb\n"
-	".subsection 2\n"
-	"6:	ldl	%1,%0;"
-	"	blt	%2,4b	# debug\n"
-	"	subl	%2,1,%2	# debug\n"
-	"	blbs	%1,6b;"
-	"	br	1b\n"
-	".previous"
-	: "=m" (*(volatile int *)lock), "=&r" (regx), "=&r" (stuck_lock)
-	: "m" (*(volatile int *)lock), "2" (stuck_lock) : "memory");
-
-	if (stuck_lock < 0) {
-		printk(KERN_WARNING "read_lock stuck at %p\n", inline_pc);
-		goto try_again;
-	}
-}
-#endif /* CONFIG_DEBUG_RWLOCK */