/*
* Share-lock a mutex, block until acquired. Recursion is allowed.
*
* Returns 0 on success, or the tsleep() return code on failure.
* An error can only be returned if PCATCH is specified in the flags.
*
* NOTE: Shared locks get a mass-wakeup so if the tsleep fails we
* do not have to chain the wakeup().
*/
static __inline int
__mtx_lock_sh(mtx_t mtx, const char *ident, int flags, int to)
{
u_int lock;
u_int nlock;
int error;
for (;;) {
lock = mtx->mtx_lock;
if ((lock & MTX_EXCLUSIVE) == 0) {
KKASSERT((lock & MTX_MASK) != MTX_MASK);
nlock = lock + 1;
if (atomic_cmpset_int(&mtx->mtx_lock, lock, nlock)) {
error = 0;
break;
}
} else {
nlock = lock | MTX_SHWANTED;
tsleep_interlock(mtx, 0);
if (atomic_cmpset_int(&mtx->mtx_lock, lock, nlock)) {
error = tsleep(mtx, flags, ident, to);
if (error)
break;
++mtx_contention_count;
/* retry */
} else {
tsleep_remove(curthread);
}
}
++mtx_collision_count;
}
return (error);
}
void
cpu_lwp_exit(void)
{
struct thread *td = curthread;
struct pcb *pcb;
npxexit();
pcb = td->td_pcb;
/* Some i386 functionality was dropped */
KKASSERT(pcb->pcb_ext == NULL);
/*
* disable all hardware breakpoints
*/
if (pcb->pcb_flags & PCB_DBREGS) {
reset_dbregs();
pcb->pcb_flags &= ~PCB_DBREGS;
}
td->td_gd->gd_cnt.v_swtch++;
crit_enter_quick(td);
if (td->td_flags & TDF_TSLEEPQ)
tsleep_remove(td);
lwkt_deschedule_self(td);
lwkt_remove_tdallq(td);
cpu_thread_exit();
}
void
cpu_lwp_exit(void)
{
struct thread *td = curthread;
struct pcb *pcb;
struct pcb_ext *ext;
/*
* If we were using a private TSS do a forced-switch to ourselves
* to switch back to the common TSS before freeing it.
*/
pcb = td->td_pcb;
if ((ext = pcb->pcb_ext) != NULL) {
crit_enter();
pcb->pcb_ext = NULL;
lwkt_switch_return(td->td_switch(td));
crit_exit();
kmem_free(&kernel_map, (vm_offset_t)ext, ctob(IOPAGES + 1));
}
user_ldt_free(pcb);
if (pcb->pcb_flags & PCB_DBREGS) {
/*
* disable all hardware breakpoints
*/
reset_dbregs();
pcb->pcb_flags &= ~PCB_DBREGS;
}
td->td_gd->gd_cnt.v_swtch++;
crit_enter_quick(td);
if (td->td_flags & TDF_TSLEEPQ)
tsleep_remove(td);
lwkt_deschedule_self(td);
lwkt_remove_tdallq(td);
cpu_thread_exit();
}
