/*
* Detach an attached XPMEM address segment.
*/
int
xpmem_detach(vaddr_t at_vaddr)
{
struct xpmem_thread_group *tg;
struct xpmem_access_permit *ap;
struct xpmem_attachment *att;
tg = xpmem_tg_ref_by_gid(current->aspace->id);
if (IS_ERR(tg))
return PTR_ERR(tg);
att = xpmem_att_ref_by_vaddr(tg, at_vaddr);
if (IS_ERR(att)) {
xpmem_tg_deref(tg);
return PTR_ERR(att);
}
mutex_lock(&att->mutex);
if (att->flags & XPMEM_FLAG_DESTROYING) {
mutex_unlock(&att->mutex);
xpmem_att_deref(att);
xpmem_tg_deref(tg);
return 0;
}
att->flags |= XPMEM_FLAG_DESTROYING;
ap = att->ap;
xpmem_ap_ref(ap);
if (current->aspace->id != ap->tg->gid) {
att->flags &= ~XPMEM_FLAG_DESTROYING;
xpmem_ap_deref(ap);
mutex_unlock(&att->mutex);
xpmem_att_deref(att);
return -EACCES;
}
__xpmem_detach_att(ap, att);
mutex_unlock(&att->mutex);
xpmem_att_destroyable(att);
xpmem_ap_deref(ap);
xpmem_att_deref(att);
xpmem_tg_deref(tg);
return 0;
}
/*
* Attach a XPMEM address segment.
*/
int
xpmem_attach(xpmem_apid_t apid,
off_t offset,
size_t size,
int att_flags,
vaddr_t * at_vaddr_p)
{
int ret, index;
vaddr_t seg_vaddr, at_vaddr;
struct xpmem_thread_group *ap_tg, *seg_tg;
struct xpmem_access_permit *ap;
struct xpmem_segment *seg;
struct xpmem_attachment *att;
if (apid <= 0)
return -EINVAL;
/* If the size is not page aligned, fix it */
if (offset_in_page(size) != 0)
size += PAGE_SIZE - offset_in_page(size);
ap_tg = xpmem_tg_ref_by_apid(apid);
if (IS_ERR(ap_tg))
return PTR_ERR(ap_tg);
ap = xpmem_ap_ref_by_apid(ap_tg, apid);
if (IS_ERR(ap)) {
xpmem_tg_deref(ap_tg);
return PTR_ERR(ap);
}
seg = ap->seg;
xpmem_seg_ref(seg);
seg_tg = seg->tg;
xpmem_tg_ref(seg_tg);
xpmem_seg_down(seg);
ret = xpmem_validate_access(ap_tg, ap, offset, size, XPMEM_RDWR, &seg_vaddr);
if (ret != 0)
goto out_1;
/* size needs to reflect page offset to start of segment */
size += offset_in_page(seg_vaddr);
if (seg->flags & XPMEM_FLAG_SHADOW) {
BUG_ON(seg->remote_apid <= 0);
/* remote - load pfns in now */
ret = xpmem_try_attach_remote(seg->segid, seg->remote_apid, offset, size, &at_vaddr);
if (ret != 0)
goto out_1;
} else {
/* not remote - simply figure out where we are smartmapped to this process */
at_vaddr = xpmem_make_smartmap_addr(seg_tg->aspace->id, seg_vaddr);
}
/* create new attach structure */
att = kmem_alloc(sizeof(struct xpmem_attachment));
if (att == NULL) {
ret = -ENOMEM;
goto out_1;
}
mutex_init(&att->mutex);
att->vaddr = seg_vaddr;
att->at_vaddr = at_vaddr;
att->at_size = size;
att->ap = ap;
att->flags = 0;
INIT_LIST_HEAD(&att->att_node);
xpmem_att_not_destroyable(att);
xpmem_att_ref(att);
/*
* The attach point where we mapped the portion of the segment the
* user was interested in is page aligned. But the start of the portion
* of the segment may not be, so we adjust the address returned to the
* user by that page offset difference so that what they see is what
* they expected to see.
*/
*at_vaddr_p = at_vaddr + offset_in_page(att->vaddr);
/* link attach structure to its access permit's att list */
spin_lock(&ap->lock);
if (ap->flags & XPMEM_FLAG_DESTROYING) {
spin_unlock(&ap->lock);
ret = -ENOENT;
goto out_2;
}
list_add_tail(&att->att_node, &ap->att_list);
/* add att to its ap_tg's hash list */
index = xpmem_att_hashtable_index(att->at_vaddr);
write_lock(&ap_tg->att_hashtable[index].lock);
list_add_tail(&att->att_hashnode, &ap_tg->att_hashtable[index].list);
write_unlock(&ap_tg->att_hashtable[index].lock);
spin_unlock(&ap->lock);
ret = 0;
out_2:
if (ret != 0) {
att->flags |= XPMEM_FLAG_DESTROYING;
xpmem_att_destroyable(att);
}
xpmem_att_deref(att);
out_1:
xpmem_seg_up(seg);
xpmem_ap_deref(ap);
xpmem_tg_deref(ap_tg);
xpmem_seg_deref(seg);
xpmem_tg_deref(seg_tg);
return ret;
}
/*
* Release an access permit and detach all associated attaches.
*/
void
xpmem_release_ap(struct xpmem_thread_group *ap_tg,
struct xpmem_access_permit *ap)
{
int index;
struct xpmem_thread_group *seg_tg;
struct xpmem_attachment *att;
struct xpmem_segment *seg;
spin_lock(&ap->lock);
if (ap->flags & XPMEM_FLAG_DESTROYING) {
spin_unlock(&ap->lock);
return;
}
ap->flags |= XPMEM_FLAG_DESTROYING;
/* deal with all attaches first */
while (!list_empty(&ap->att_list)) {
att = list_entry((&ap->att_list)->next, struct xpmem_attachment,
att_node);
xpmem_att_ref(att);
spin_unlock(&ap->lock);
xpmem_detach_att(ap, att);
xpmem_att_deref(att);
spin_lock(&ap->lock);
}
spin_unlock(&ap->lock);
/*
* Remove access structure from its hash list.
* This is done after the xpmem_detach_att to prevent any racing
* thread from looking up access permits for the owning thread group
* and not finding anything, assuming everything is clean, and
* freeing the mm before xpmem_detach_att has a chance to
* use it.
*/
index = xpmem_ap_hashtable_index(ap->apid);
write_lock(&ap_tg->ap_hashtable[index].lock);
list_del_init(&ap->ap_hashnode);
write_unlock(&ap_tg->ap_hashtable[index].lock);
/* the ap's seg and the seg's tg were ref'd in xpmem_get() */
seg = ap->seg;
seg_tg = seg->tg;
/* remove ap from its seg's access permit list */
spin_lock(&seg->lock);
list_del_init(&ap->ap_node);
spin_unlock(&seg->lock);
/* Try to teardown a shadow segment */
if (seg->flags & XPMEM_FLAG_SHADOW)
xpmem_remove_seg(seg_tg, seg);
xpmem_seg_deref(seg); /* deref of xpmem_get()'s ref */
xpmem_tg_deref(seg_tg); /* deref of xpmem_get()'s ref */
xpmem_ap_destroyable(ap);
}