[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 fc5ef90c4fc9..24ae9a366073 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 e211aa7404e6..da0be3465791 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 */