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Upadte. 

2000-04-11  Ulrich Drepper  <drepper@redhat.com>

	* internals.h: Define MEMORY_BARRIER as empty if not defined already.
	* spinlock.c (__pthread_lock): Add memory barriers.
	(__pthread_unlock): Likewise.
	* sysdeps/alpha/pt-machine.h (MEMORY_BARRIER): Define using mb
	instruction.
	(RELEASE): Not needed anymore.
	(__compare_and_swap): Mark asm as modifying memory.
	* sysdeps/powerpc/pt-machine.h (sync): Remove.  Replace with definition
	of MEMORY_BARRIER.
	(__compare_and_swap): Use MEMORY_BARRIER instead of sync.
	* sysdeps/sparc/sparc32/pt-machine.h (RELEASE): Not needed anymore.
	(MEMORY_BARRIER): Define using stbar.
	* sysdeps/sparc/sparc64/pt-machine.h (MEMORY_BARRIER): Define using
	stbar.
	(__compare_and_swap): Use MEMORY_BARRIER to ensure ordering.
	Patch by Xavier Leroy <Xavier.Leroy@inria.fr> based on comments by
	Mike Burrows <m3b@pa.dec.com>.
This commit is contained in:
Ulrich Drepper 2000-04-11 17:03:03 +00:00
parent e7c036b39e
commit de26253715
7 changed files with 61 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
linuxthreads/ChangeLog
View File

@ -1,3 +1,23 @@
2000-04-11 Ulrich Drepper <drepper@redhat.com>
* internals.h: Define MEMORY_BARRIER as empty if not defined already.
* spinlock.c (__pthread_lock): Add memory barriers.
(__pthread_unlock): Likewise.
* sysdeps/alpha/pt-machine.h (MEMORY_BARRIER): Define using mb
instruction.
(RELEASE): Not needed anymore.
(__compare_and_swap): Mark asm as modifying memory.
* sysdeps/powerpc/pt-machine.h (sync): Remove. Replace with definition
of MEMORY_BARRIER.
(__compare_and_swap): Use MEMORY_BARRIER instead of sync.
* sysdeps/sparc/sparc32/pt-machine.h (RELEASE): Not needed anymore.
(MEMORY_BARRIER): Define using stbar.
* sysdeps/sparc/sparc64/pt-machine.h (MEMORY_BARRIER): Define using
stbar.
(__compare_and_swap): Use MEMORY_BARRIER to ensure ordering.
Patch by Xavier Leroy <Xavier.Leroy@inria.fr> based on comments by
Mike Burrows <m3b@pa.dec.com>.
2000-04-09 Ulrich Drepper <drepper@redhat.com>
* signals.c (sigaction): Fix return value for the case SIG is one

7
linuxthreads/internals.h
View File

@ -357,6 +357,13 @@ static inline pthread_descr thread_self (void)
#endif
}
/* If MEMORY_BARRIER isn't defined in pt-machine.h, assume the architecture
doesn't need a memory barrier instruction (e.g. Intel x86) */
#ifndef MEMORY_BARRIER
#define MEMORY_BARRIER()
#endif
/* Max number of times we must spin on a spinlock calling sched_yield().
After MAX_SPIN_COUNT iterations, we put the calling thread to sleep. */

17
linuxthreads/spinlock.c
View File

@ -54,6 +54,9 @@ void internal_function __pthread_lock(struct _pthread_fastlock * lock,
if (self != NULL) {
ASSERT(self->p_nextlock == NULL);
THREAD_SETMEM(self, p_nextlock, (pthread_descr) oldstatus);
/* Make sure the store in p_nextlock completes before performing
the compare-and-swap */
MEMORY_BARRIER();
}
} while(! compare_and_swap(&lock->__status, oldstatus, newstatus,
&lock->__spinlock));
@ -108,8 +111,17 @@ again:
maxprio = thr->p_priority;
}
ptr = &(thr->p_nextlock);
/* Prevent reordering of the load of lock->__status above and the
load of *ptr below, as well as reordering of *ptr between
several iterations of the while loop. Some processors (e.g.
multiprocessor Alphas) could perform such reordering even though
the loads are dependent. */
MEMORY_BARRIER();
thr = *ptr;
}
/* Prevent reordering of the load of lock->__status above and
thr->p_nextlock below */
MEMORY_BARRIER();
/* Remove max prio thread from waiting list. */
if (maxptr == (pthread_descr *) &lock->__status) {
/* If max prio thread is at head, remove it with compare-and-swap
@ -124,6 +136,9 @@ again:
thr = *maxptr;
*maxptr = thr->p_nextlock;
}
/* Prevent reordering of store to *maxptr above and store to thr->p_nextlock
below */
MEMORY_BARRIER();
/* Wake up the selected waiting thread */
thr->p_nextlock = NULL;
restart(thr);
@ -149,6 +164,8 @@ int __pthread_compare_and_swap(long * ptr, long oldval, long newval,
} else {
res = 0;
}
/* Prevent reordering of store to *ptr above and store to *spinlock below */
MEMORY_BARRIER();
*spinlock = 0;
return res;
}

12
linuxthreads/sysdeps/alpha/pt-machine.h
View File

@ -32,6 +32,10 @@
register char *stack_pointer __asm__("$30");
/* Memory barrier; default is to do nothing */
#define MEMORY_BARRIER() __asm__ __volatile__("mb" : : : "memory")
/* Spinlock implementation; required. */
PT_EI long int
testandset (int *spinlock)
@ -55,11 +59,6 @@ testandset (int *spinlock)
return ret;
}
/* Spinlock release; default is just set to zero. */
#define RELEASE(spinlock) \
__asm__ __volatile__("mb" : : : "memory"); \
*spinlock = 0
/* Begin allocating thread stacks at this address. Default is to allocate
them just below the initial program stack. */
@ -102,7 +101,8 @@ __compare_and_swap (long int *p, long int oldval, long int newval)
"2:\tmb\n"
"/* End compare & swap */"
: "=&r"(ret), "=m"(*p)
: "r"(oldval), "r"(newval), "m"(*p));
: "r"(oldval), "r"(newval), "m"(*p)
: "memory");
return ret;
}

9
linuxthreads/sysdeps/powerpc/pt-machine.h
View File

@ -27,12 +27,7 @@
/* For multiprocessor systems, we want to ensure all memory accesses
are completed before we reset a lock. */
#if 0
/* on non multiprocessor systems, you can just: */
#define sync() /* nothing */
#else
#define sync() __asm__ __volatile__ ("sync")
#endif
#define MEMORY_BARRIER() __asm__ __volatile__ ("sync" : : : "memory")
/* Get some notion of the current stack. Need not be exactly the top
of the stack, just something somewhere in the current frame. */
@ -64,6 +59,6 @@ __compare_and_swap (long int *p, long int oldval, long int newval)
: "=&r"(ret)
: "r"(p), "r"(newval), "r"(oldval)
: "cr0", "memory");
sync();
MEMORY_BARRIER();
return ret == 0;
}

5
linuxthreads/sysdeps/sparc/sparc32/pt-machine.h
View File

@ -37,9 +37,8 @@ testandset (int *spinlock)
}
/* Spinlock release; default is just set to zero. */
#define RELEASE(spinlock) \
__asm__ __volatile__("stbar; stb %1,%0" : "=m"(*(spinlock)) : "r"(0));
/* Memory barrier; default is to do nothing */
#define MEMORY_BARRIER() __asm__ __volatile__("stbar" : : : "memory")
/* Get some notion of the current stack. Need not be exactly the top

8
linuxthreads/sysdeps/sparc/sparc64/pt-machine.h
View File

@ -37,6 +37,12 @@ testandset (int *spinlock)
}
/* Memory barrier; default is to do nothing */
/* FIXME: is stbar OK, or should we use the more general membar instruction?
If so, which mode to pass to membar? */
#define MEMORY_BARRIER() __asm__ __volatile__("stbar" : : : "memory")
/* Get some notion of the current stack. Need not be exactly the top
of the stack, just something somewhere in the current frame. */
#define CURRENT_STACK_FRAME stack_pointer
@ -66,7 +72,7 @@ __compare_and_swap (long int *p, long int oldval, long int newval)
__asm__ __volatile__ ("casx [%4], %2, %0"
: "=r"(readval), "=m"(*p)
: "r"(oldval), "m"(*p), "r"(p), "0"(newval));
MEMORY_BARRIER();
return readval == oldval;
}