static dm_fsreg_t *
dm_find_fsreg_and_lock(
fsid_t *fsidp,
int *lcp) /* address of returned lock cookie */
{
dm_fsreg_t *fsrp;
for (;;) {
*lcp = mutex_spinlock(&dm_reg_lock);
if ((fsrp = dm_find_fsreg(fsidp)) == NULL) {
mutex_spinunlock(&dm_reg_lock, *lcp);
return(NULL);
}
if (nested_spintrylock(&fsrp->fr_lock)) {
nested_spinunlock(&dm_reg_lock);
return(fsrp); /* success */
}
/* If the second lock is not available, drop the first and
start over. This gives the CPU a chance to process any
interrupts, and also allows processes which want a fr_lock
for a different filesystem to proceed.
*/
mutex_spinunlock(&dm_reg_lock, *lcp);
}
}
int
dm_find_session_and_lock(
dm_sessid_t sid,
dm_session_t **sessionpp,
int *lcp) /* addr of returned lock cookie */
{
int error;
for (;;) {
*lcp = mutex_spinlock(&dm_session_lock);
if ((error = dm_find_session(sid, sessionpp)) != 0) {
mutex_spinunlock(&dm_session_lock, *lcp);
return(error);
}
if (nested_spintrylock(&(*sessionpp)->sn_qlock)) {
nested_spinunlock(&dm_session_lock);
return(0); /* success */
}
/* If the second lock is not available, drop the first and
start over. This gives the CPU a chance to process any
interrupts, and also allows processes which want a sn_qlock
for a different session to proceed.
*/
mutex_spinunlock(&dm_session_lock, *lcp);
}
}
void
dm_uninit(void)
{
int lc;
dm_session_t *s;
static void unlink_session( dm_session_t *s);
if(dm_sessions_active) {
printk(KERN_ERR "xfs dmapi is being unloaded while there are active sessions\n");
while( dm_sessions_active ) {
/* this for-loop mostly from dm_find_session_and_lock() */
for (;;) {
s = dm_sessions;
lc = mutex_spinlock(&dm_session_lock);
if (nested_spintrylock(&s->sn_qlock)) {
nested_spinunlock(&dm_session_lock);
break; /* success */
}
mutex_spinunlock(&dm_session_lock, lc);
}/* for */
/* this cleanup stuff mostly from dm_destroy_session() */
if (s->sn_newq.eq_head || s->sn_readercnt || s->sn_delq.eq_head) {
/* busy session */
printk(KERN_ERR " sessid %d (%s) is busy\n", s->sn_sessid, s->sn_info);
nested_spinunlock(&s->sn_qlock);
mutex_spinunlock(&dm_session_lock, lc);
break; /* do not continue */
}
else {
unlink_session(s);
nested_spinunlock(&s->sn_qlock);
mutex_spinunlock(&dm_session_lock, lc);
dm_clear_fsreg(s);
spinlock_destroy(&s->sn_qlock);
sv_destroy(&s->sn_readerq);
sv_destroy(&s->sn_writerq);
kmem_free(s, sizeof *s);
printk(KERN_ERR " sessid %d (%s) destroyed\n", s->sn_sessid, s->sn_info);
}
}/*while*/
}
/* If any of these are still locked, then we should not allow
* an unload.
* XXX can any of these be held when no sessions exist?
* - yes, dm_session_lock is acquired prior to adding a new session
* - no, dm_token_lock is only held when a session is locked
* - ?, dm_reg_lock (XXX lookup this one)
*/
if( spin_is_locked(&dm_session_lock) )
printk(KERN_ERR "xfs dmapi is being unloaded while dm_session_lock is held\n");
if( spin_is_locked(&dm_token_lock) )
printk(KERN_ERR "xfs dmapi is being unloaded while dm_token_lock is held\n");
if( spin_is_locked(&dm_reg_lock) )
printk(KERN_ERR "xfs dmapi is being unloaded while dm_reg_lock is held\n");
spinlock_destroy(&dm_session_lock);
spinlock_destroy(&dm_token_lock);
spinlock_destroy(&dm_reg_lock);
}