1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
377 lines
8.0 KiB
C
377 lines
8.0 KiB
C
/* $Id: debuglocks.c,v 1.9 2001/11/17 00:10:48 davem Exp $
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* debuglocks.c: Debugging versions of SMP locking primitives.
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*
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* Copyright (C) 1998 David S. Miller (davem@redhat.com)
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*/
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#include <linux/config.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <asm/system.h>
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#ifdef CONFIG_SMP
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#define GET_CALLER(PC) __asm__ __volatile__("mov %%i7, %0" : "=r" (PC))
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static inline void show (char *str, spinlock_t *lock, unsigned long caller)
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{
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int cpu = smp_processor_id();
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printk("%s(%p) CPU#%d stuck at %08x, owner PC(%08x):CPU(%x)\n",
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str, lock, cpu, (unsigned int) caller,
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lock->owner_pc, lock->owner_cpu);
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}
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static inline void show_read (char *str, rwlock_t *lock, unsigned long caller)
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{
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int cpu = smp_processor_id();
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printk("%s(%p) CPU#%d stuck at %08x, writer PC(%08x):CPU(%x)\n",
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str, lock, cpu, (unsigned int) caller,
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lock->writer_pc, lock->writer_cpu);
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}
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static inline void show_write (char *str, rwlock_t *lock, unsigned long caller)
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{
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int cpu = smp_processor_id();
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int i;
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printk("%s(%p) CPU#%d stuck at %08x\n",
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str, lock, cpu, (unsigned int) caller);
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printk("Writer: PC(%08x):CPU(%x)\n",
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lock->writer_pc, lock->writer_cpu);
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printk("Readers:");
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for (i = 0; i < NR_CPUS; i++)
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if (lock->reader_pc[i])
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printk(" %d[%08x]", i, lock->reader_pc[i]);
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printk("\n");
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}
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#undef INIT_STUCK
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#define INIT_STUCK 100000000
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void _do_spin_lock(spinlock_t *lock, char *str)
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{
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unsigned long caller, val;
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int stuck = INIT_STUCK;
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int cpu = get_cpu();
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int shown = 0;
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GET_CALLER(caller);
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again:
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__asm__ __volatile__("ldstub [%1], %0"
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: "=r" (val)
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: "r" (&(lock->lock))
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: "memory");
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membar("#StoreLoad | #StoreStore");
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if (val) {
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while (lock->lock) {
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if (!--stuck) {
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if (shown++ <= 2)
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show(str, lock, caller);
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stuck = INIT_STUCK;
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}
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membar("#LoadLoad");
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}
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goto again;
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}
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lock->owner_pc = ((unsigned int)caller);
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lock->owner_cpu = cpu;
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current->thread.smp_lock_count++;
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current->thread.smp_lock_pc = ((unsigned int)caller);
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put_cpu();
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}
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int _do_spin_trylock(spinlock_t *lock)
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{
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unsigned long val, caller;
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int cpu = get_cpu();
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GET_CALLER(caller);
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__asm__ __volatile__("ldstub [%1], %0"
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: "=r" (val)
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: "r" (&(lock->lock))
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: "memory");
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membar("#StoreLoad | #StoreStore");
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if (!val) {
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lock->owner_pc = ((unsigned int)caller);
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lock->owner_cpu = cpu;
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current->thread.smp_lock_count++;
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current->thread.smp_lock_pc = ((unsigned int)caller);
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}
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put_cpu();
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return val == 0;
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}
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void _do_spin_unlock(spinlock_t *lock)
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{
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lock->owner_pc = 0;
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lock->owner_cpu = NO_PROC_ID;
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membar("#StoreStore | #LoadStore");
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lock->lock = 0;
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current->thread.smp_lock_count--;
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}
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/* Keep INIT_STUCK the same... */
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void _do_read_lock (rwlock_t *rw, char *str)
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{
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unsigned long caller, val;
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int stuck = INIT_STUCK;
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int cpu = get_cpu();
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int shown = 0;
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GET_CALLER(caller);
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wlock_again:
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/* Wait for any writer to go away. */
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while (((long)(rw->lock)) < 0) {
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if (!--stuck) {
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if (shown++ <= 2)
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show_read(str, rw, caller);
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stuck = INIT_STUCK;
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}
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membar("#LoadLoad");
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}
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/* Try once to increment the counter. */
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__asm__ __volatile__(
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" ldx [%0], %%g1\n"
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" brlz,a,pn %%g1, 2f\n"
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" mov 1, %0\n"
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" add %%g1, 1, %%g7\n"
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" casx [%0], %%g1, %%g7\n"
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" sub %%g1, %%g7, %0\n"
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"2:" : "=r" (val)
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: "0" (&(rw->lock))
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: "g1", "g7", "memory");
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membar("#StoreLoad | #StoreStore");
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if (val)
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goto wlock_again;
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rw->reader_pc[cpu] = ((unsigned int)caller);
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current->thread.smp_lock_count++;
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current->thread.smp_lock_pc = ((unsigned int)caller);
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put_cpu();
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}
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void _do_read_unlock (rwlock_t *rw, char *str)
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{
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unsigned long caller, val;
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int stuck = INIT_STUCK;
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int cpu = get_cpu();
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int shown = 0;
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GET_CALLER(caller);
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/* Drop our identity _first_. */
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rw->reader_pc[cpu] = 0;
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current->thread.smp_lock_count--;
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runlock_again:
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/* Spin trying to decrement the counter using casx. */
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__asm__ __volatile__(
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" membar #StoreLoad | #LoadLoad\n"
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" ldx [%0], %%g1\n"
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" sub %%g1, 1, %%g7\n"
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" casx [%0], %%g1, %%g7\n"
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" membar #StoreLoad | #StoreStore\n"
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" sub %%g1, %%g7, %0\n"
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: "=r" (val)
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: "0" (&(rw->lock))
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: "g1", "g7", "memory");
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if (val) {
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if (!--stuck) {
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if (shown++ <= 2)
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show_read(str, rw, caller);
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stuck = INIT_STUCK;
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}
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goto runlock_again;
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}
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put_cpu();
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}
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void _do_write_lock (rwlock_t *rw, char *str)
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{
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unsigned long caller, val;
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int stuck = INIT_STUCK;
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int cpu = get_cpu();
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int shown = 0;
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GET_CALLER(caller);
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wlock_again:
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/* Spin while there is another writer. */
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while (((long)rw->lock) < 0) {
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if (!--stuck) {
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if (shown++ <= 2)
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show_write(str, rw, caller);
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stuck = INIT_STUCK;
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}
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membar("#LoadLoad");
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}
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/* Try to acuire the write bit. */
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__asm__ __volatile__(
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" mov 1, %%g3\n"
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" sllx %%g3, 63, %%g3\n"
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" ldx [%0], %%g1\n"
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" brlz,pn %%g1, 1f\n"
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" or %%g1, %%g3, %%g7\n"
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" casx [%0], %%g1, %%g7\n"
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" membar #StoreLoad | #StoreStore\n"
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" ba,pt %%xcc, 2f\n"
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" sub %%g1, %%g7, %0\n"
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"1: mov 1, %0\n"
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"2:" : "=r" (val)
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: "0" (&(rw->lock))
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: "g3", "g1", "g7", "memory");
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if (val) {
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/* We couldn't get the write bit. */
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if (!--stuck) {
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if (shown++ <= 2)
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show_write(str, rw, caller);
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stuck = INIT_STUCK;
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}
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goto wlock_again;
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}
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if ((rw->lock & ((1UL<<63)-1UL)) != 0UL) {
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/* Readers still around, drop the write
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* lock, spin, and try again.
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*/
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if (!--stuck) {
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if (shown++ <= 2)
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show_write(str, rw, caller);
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stuck = INIT_STUCK;
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}
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__asm__ __volatile__(
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" mov 1, %%g3\n"
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" sllx %%g3, 63, %%g3\n"
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"1: ldx [%0], %%g1\n"
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" andn %%g1, %%g3, %%g7\n"
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" casx [%0], %%g1, %%g7\n"
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" cmp %%g1, %%g7\n"
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" bne,pn %%xcc, 1b\n"
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" membar #StoreLoad | #StoreStore"
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: /* no outputs */
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: "r" (&(rw->lock))
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: "g3", "g1", "g7", "cc", "memory");
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while(rw->lock != 0) {
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if (!--stuck) {
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if (shown++ <= 2)
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show_write(str, rw, caller);
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stuck = INIT_STUCK;
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}
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membar("#LoadLoad");
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}
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goto wlock_again;
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}
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/* We have it, say who we are. */
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rw->writer_pc = ((unsigned int)caller);
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rw->writer_cpu = cpu;
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current->thread.smp_lock_count++;
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current->thread.smp_lock_pc = ((unsigned int)caller);
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put_cpu();
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}
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void _do_write_unlock(rwlock_t *rw)
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{
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unsigned long caller, val;
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int stuck = INIT_STUCK;
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int shown = 0;
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GET_CALLER(caller);
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/* Drop our identity _first_ */
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rw->writer_pc = 0;
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rw->writer_cpu = NO_PROC_ID;
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current->thread.smp_lock_count--;
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wlock_again:
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__asm__ __volatile__(
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" membar #StoreLoad | #LoadLoad\n"
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" mov 1, %%g3\n"
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" sllx %%g3, 63, %%g3\n"
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" ldx [%0], %%g1\n"
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" andn %%g1, %%g3, %%g7\n"
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" casx [%0], %%g1, %%g7\n"
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" membar #StoreLoad | #StoreStore\n"
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" sub %%g1, %%g7, %0\n"
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: "=r" (val)
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: "0" (&(rw->lock))
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: "g3", "g1", "g7", "memory");
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if (val) {
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if (!--stuck) {
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if (shown++ <= 2)
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show_write("write_unlock", rw, caller);
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stuck = INIT_STUCK;
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}
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goto wlock_again;
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}
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}
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int _do_write_trylock (rwlock_t *rw, char *str)
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{
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unsigned long caller, val;
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int cpu = get_cpu();
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GET_CALLER(caller);
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/* Try to acuire the write bit. */
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__asm__ __volatile__(
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" mov 1, %%g3\n"
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" sllx %%g3, 63, %%g3\n"
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" ldx [%0], %%g1\n"
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" brlz,pn %%g1, 1f\n"
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" or %%g1, %%g3, %%g7\n"
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" casx [%0], %%g1, %%g7\n"
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" membar #StoreLoad | #StoreStore\n"
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" ba,pt %%xcc, 2f\n"
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" sub %%g1, %%g7, %0\n"
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"1: mov 1, %0\n"
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"2:" : "=r" (val)
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: "0" (&(rw->lock))
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: "g3", "g1", "g7", "memory");
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if (val) {
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put_cpu();
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return 0;
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}
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if ((rw->lock & ((1UL<<63)-1UL)) != 0UL) {
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/* Readers still around, drop the write
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* lock, return failure.
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*/
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__asm__ __volatile__(
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" mov 1, %%g3\n"
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" sllx %%g3, 63, %%g3\n"
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"1: ldx [%0], %%g1\n"
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" andn %%g1, %%g3, %%g7\n"
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" casx [%0], %%g1, %%g7\n"
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" cmp %%g1, %%g7\n"
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" bne,pn %%xcc, 1b\n"
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" membar #StoreLoad | #StoreStore"
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: /* no outputs */
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: "r" (&(rw->lock))
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: "g3", "g1", "g7", "cc", "memory");
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put_cpu();
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return 0;
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}
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/* We have it, say who we are. */
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rw->writer_pc = ((unsigned int)caller);
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rw->writer_cpu = cpu;
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current->thread.smp_lock_count++;
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current->thread.smp_lock_pc = ((unsigned int)caller);
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put_cpu();
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return 1;
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}
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#endif /* CONFIG_SMP */
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