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o Make the defenition of _set_curthread() match its declaration

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in thr_private.h

o Lock down the ldt_entries array and ldt_free, which points to
  the next free slot. As noted in the comments, it's necessary
  to special case the initial_thread because %gs is not setup
  for it yet. This is ok because that early in the program there
  won't be any reentrancy issues anyways.

Approved by:	re/blanket libthr
This commit is contained in:
Mike Makonnen 2003-05-21 08:21:24 +00:00
parent 3284b9ee87
commit 509d72c4b9
1 changed files with 27 additions and 5 deletions
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32
lib/libthr/arch/i386/i386/_setcurthread.c
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@ -29,21 +29,29 @@
#include <sys/types.h>
#include <sys/ucontext.h>
#include <pthread.h>
#include <stdio.h>
#include <machine/sysarch.h>
#include <machine/segments.h>
#include "thr_private.h"
#define MAXTHR 128
#define LDT_INDEX(x) (((long)(x) - (long)ldt_entries) / sizeof(ldt_entries[0]))
void **ldt_free = NULL;
static int ldt_inited = 0;
void *ldt_entries[MAXTHR];
void **ldt_free = NULL;
void *ldt_entries[MAXTHR];
static int ldt_inited = 0;
static spinlock_t ldt_lock = _SPINLOCK_INITIALIZER;
static void ldt_init(void);
/*
* Initialize the array of ldt_entries and the next free slot.
* This routine must be called with the global ldt lock held.
*/
static void
ldt_init(void)
{
@ -62,21 +70,32 @@ ldt_init(void)
void
_retire_thread(void *entry)
{
_SPINLOCK(&ldt_lock);
if (ldt_free == NULL)
*(void **)entry = NULL;
else
*(void **)entry = *ldt_free;
ldt_free = entry;
_SPINUNLOCK(&ldt_lock);
}
void *
_set_curthread(ucontext_t *uc, void *thr)
_set_curthread(ucontext_t *uc, struct pthread *thr)
{
union descriptor desc;
void **ldt_entry;
int ldt_index;
int error;
/*
* If we are setting up the initial thread, the gs register
* won't be setup for the current thread. In any case, we
* don't need protection from re-entrancy at this point in
* the life of the program.
*/
if (thr != _thread_initial)
_SPINLOCK(&ldt_lock);
if (ldt_inited == NULL)
ldt_init();
@ -89,11 +108,14 @@ _set_curthread(ucontext_t *uc, void *thr)
ldt_entry = ldt_free;
ldt_free = (void **)*ldt_entry;
if (thr != _thread_initial)
_SPINUNLOCK(&ldt_lock);
/*
* Cache the address of the thread structure here. This is
* what the gs register will point to.
*/
*ldt_entry = thr;
*ldt_entry = (void *)thr;
ldt_index = LDT_INDEX(ldt_entry);
bzero(&desc, sizeof(desc));