/**
* qib_lkey_ok - check IB SGE for validity and initialize
* @rkt: table containing lkey to check SGE against
* @pd: protection domain
* @isge: outgoing internal SGE
* @sge: SGE to check
* @acc: access flags
*
* Return 1 if valid and successful, otherwise returns 0.
*
* increments the reference count upon success
*
* Check the IB SGE for validity and initialize our internal version
* of it.
*/
int qib_lkey_ok(struct qib_lkey_table *rkt, struct qib_pd *pd,
struct qib_sge *isge, struct ib_sge *sge, int acc)
{
struct qib_mregion *mr;
unsigned n, m;
size_t off;
/*
* We use LKEY == zero for kernel virtual addresses
* (see qib_get_dma_mr and qib_dma.c).
*/
rcu_read_lock();
if (sge->lkey == 0) {
struct qib_ibdev *dev = to_idev(pd->ibpd.device);
if (pd->user)
goto bail;
mr = rcu_dereference(dev->dma_mr);
if (!mr)
goto bail;
if (unlikely(!atomic_inc_not_zero(&mr->refcount)))
goto bail;
rcu_read_unlock();
isge->mr = mr;
isge->vaddr = (void *) sge->addr;
isge->length = sge->length;
isge->sge_length = sge->length;
isge->m = 0;
isge->n = 0;
goto ok;
}
mr = rcu_dereference(
rkt->table[(sge->lkey >> (32 - ib_qib_lkey_table_size))]);
if (unlikely(!mr || mr->lkey != sge->lkey || mr->pd != &pd->ibpd))
goto bail;
off = sge->addr - mr->user_base;
if (unlikely(sge->addr < mr->user_base ||
off + sge->length > mr->length ||
(mr->access_flags & acc) != acc))
goto bail;
if (unlikely(!atomic_inc_not_zero(&mr->refcount)))
goto bail;
rcu_read_unlock();
off += mr->offset;
if (mr->page_shift) {
/*
page sizes are uniform power of 2 so no loop is necessary
entries_spanned_by_off is the number of times the loop below
would have executed.
*/
size_t entries_spanned_by_off;
entries_spanned_by_off = off >> mr->page_shift;
off -= (entries_spanned_by_off << mr->page_shift);
m = entries_spanned_by_off/QIB_SEGSZ;
n = entries_spanned_by_off%QIB_SEGSZ;
} else {
/*
* this lookup function only uses RCU to protect the skiplist indexing
* structs. The actual slots are protected by full locks.
*/
struct sl_slot *skiplist_lookup(struct sl_list *list, unsigned long key,
unsigned long size)
{
struct sl_leaf *leaf;
struct sl_slot *slot_ret = NULL;
struct sl_node *p;
int slot;
int ret;
again:
rcu_read_lock();
leaf = __skiplist_lookup_leaf(list, &p, key, size);
if (leaf) {
sl_lock_node(&leaf->node);
if (!verify_key_in_leaf(leaf, key, size)) {
sl_unlock_node(&leaf->node);
rcu_read_unlock();
goto again;
}
ret = skiplist_search_leaf(leaf, key, size, &slot);
if (ret == 0) {
slot_ret = leaf->ptrs[slot];
if (atomic_inc_not_zero(&slot_ret->refs) == 0)
slot_ret = NULL;
}
sl_unlock_node(&leaf->node);
}
rcu_read_unlock();
return slot_ret;
}
/**
* batadv_dat_entry_hash_find - looks for a given dat_entry in the local hash
* table
* @bat_priv: the bat priv with all the soft interface information
* @ip: search key
*
* Returns the dat_entry if found, NULL otherwise
*/
static struct batadv_dat_entry *
batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip)
{
struct hlist_head *head;
struct hlist_node *node;
struct batadv_dat_entry *dat_entry, *dat_entry_tmp = NULL;
struct batadv_hashtable *hash = bat_priv->dat.hash;
uint32_t index;
if (!hash)
return NULL;
index = batadv_hash_dat(&ip, hash->size);
head = &hash->table[index];
rcu_read_lock();
hlist_for_each_entry_rcu(dat_entry, node, head, hash_entry) {
if (dat_entry->ip != ip)
continue;
if (!atomic_inc_not_zero(&dat_entry->refcount))
continue;
dat_entry_tmp = dat_entry;
break;
}
rcu_read_unlock();
return dat_entry_tmp;
}
/* try to find an element in the hash, return NULL if not found */
struct ws_sta *ws_hash_find(struct ws_hash *hash, u8 *mac)
{
struct ws_sta *res = NULL, *tmp_sta;
spinlock_t *list_lock; /* spinlock to protect write access */
struct hlist_head *head;
u32 index;
index = ws_hash_choose(mac);
head = &hash->table[index];
list_lock = &hash->list_locks[index];
rcu_read_lock();
hlist_for_each_entry_rcu(tmp_sta, head, hash_entry) {
if (ether_addr_equal(mac, tmp_sta->mac))
continue;
if (!atomic_inc_not_zero(&tmp_sta->refcount))
continue;
res = tmp_sta;
break;
}
rcu_read_unlock();
return res;
}
/**
* batadv_claim_hash_find
* @bat_priv: the bat priv with all the soft interface information
* @data: search data (may be local/static data)
*
* looks for a claim in the hash, and returns it if found
* or NULL otherwise.
*/
static struct batadv_bla_claim
*batadv_claim_hash_find(struct batadv_priv *bat_priv,
struct batadv_bla_claim *data)
{
struct batadv_hashtable *hash = bat_priv->bla.claim_hash;
struct hlist_head *head;
struct batadv_bla_claim *claim;
struct batadv_bla_claim *claim_tmp = NULL;
int index;
if (!hash)
return NULL;
index = batadv_choose_claim(data, hash->size);
head = &hash->table[index];
rcu_read_lock();
hlist_for_each_entry_rcu(claim, head, hash_entry) {
if (!batadv_compare_claim(&claim->hash_entry, data))
continue;
if (!atomic_inc_not_zero(&claim->refcount))
continue;
claim_tmp = claim;
break;
}
rcu_read_unlock();
return claim_tmp;
}
/**
* batadv_dat_entry_hash_find - look for a given dat_entry in the local hash
* table
* @bat_priv: the bat priv with all the soft interface information
* @ip: search key
* @vid: VLAN identifier
*
* Returns the dat_entry if found, NULL otherwise.
*/
static struct batadv_dat_entry *
batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
unsigned short vid)
{
struct hlist_head *head;
struct batadv_dat_entry to_find, *dat_entry, *dat_entry_tmp = NULL;
struct batadv_hashtable *hash = bat_priv->dat.hash;
u32 index;
if (!hash)
return NULL;
to_find.ip = ip;
to_find.vid = vid;
index = batadv_hash_dat(&to_find, hash->size);
head = &hash->table[index];
rcu_read_lock();
hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
if (dat_entry->ip != ip)
continue;
if (!atomic_inc_not_zero(&dat_entry->refcount))
continue;
dat_entry_tmp = dat_entry;
break;
}
rcu_read_unlock();
return dat_entry_tmp;
}
int ptrace_get_breakpoints(struct task_struct *tsk)
{
if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
return 0;
return -1;
}
static struct sock *__llc_lookup_listener(struct llc_sap *sap,
struct llc_addr *laddr)
{
struct sock *rc;
struct hlist_nulls_node *node;
int slot = llc_sk_laddr_hashfn(sap, laddr);
struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
rcu_read_lock();
again:
sk_nulls_for_each_rcu(rc, node, laddr_hb) {
if (llc_listener_match(sap, laddr, rc)) {
/* Extra checks required by SLAB_DESTROY_BY_RCU */
if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
goto again;
if (unlikely(llc_sk(rc)->sap != sap ||
!llc_listener_match(sap, laddr, rc))) {
sock_put(rc);
continue;
}
goto found;
}
}
rc = NULL;
/*
* if the nulls value we got at the end of this lookup is
* not the expected one, we must restart lookup.
* We probably met an item that was moved to another chain.
*/
if (unlikely(get_nulls_value(node) != slot))
goto again;
found:
rcu_read_unlock();
return rc;
}
static void *m_start(struct seq_file *m, loff_t *pos)
{
struct proc_maps_private *priv = m->private;
struct mm_struct *mm;
struct rb_node *p;
loff_t n = *pos;
/* pin the task and mm whilst we play with them */
priv->task = get_proc_task(priv->inode);
if (!priv->task)
return ERR_PTR(-ESRCH);
mm = priv->mm;
if (!mm || !atomic_inc_not_zero(&mm->mm_users))
return NULL;
down_read(&mm->mmap_sem);
/* start from the Nth VMA */
for (p = rb_first(&mm->mm_rb); p; p = rb_next(p))
if (n-- == 0)
return p;
up_read(&mm->mmap_sem);
mmput(mm);
return NULL;
}
static struct sock *__llc_lookup_listener(struct llc_sap *sap,
struct llc_addr *laddr)
{
struct sock *rc;
struct hlist_nulls_node *node;
int slot = llc_sk_laddr_hashfn(sap, laddr);
struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
rcu_read_lock();
again:
sk_nulls_for_each_rcu(rc, node, laddr_hb) {
if (llc_listener_match(sap, laddr, rc)) {
if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
goto again;
if (unlikely(llc_sk(rc)->sap != sap ||
!llc_listener_match(sap, laddr, rc))) {
sock_put(rc);
continue;
}
goto found;
}
}
rc = NULL;
if (unlikely(get_nulls_value(node) != slot))
goto again;
found:
rcu_read_unlock();
return rc;
}
/**
* batadv_backbone_hash_find - looks for a claim in the hash
* @bat_priv: the bat priv with all the soft interface information
* @addr: the address of the originator
* @vid: the VLAN ID
*
* Returns claim if found or NULL otherwise.
*/
static struct batadv_bla_backbone_gw *
batadv_backbone_hash_find(struct batadv_priv *bat_priv,
uint8_t *addr, unsigned short vid)
{
struct batadv_hashtable *hash = bat_priv->bla.backbone_hash;
struct hlist_head *head;
struct batadv_bla_backbone_gw search_entry, *backbone_gw;
struct batadv_bla_backbone_gw *backbone_gw_tmp = NULL;
int index;
if (!hash)
return NULL;
ether_addr_copy(search_entry.orig, addr);
search_entry.vid = vid;
index = batadv_choose_backbone_gw(&search_entry, hash->size);
head = &hash->table[index];
rcu_read_lock();
hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
if (!batadv_compare_backbone_gw(&backbone_gw->hash_entry,
&search_entry))
continue;
if (!atomic_inc_not_zero(&backbone_gw->refcount))
continue;
backbone_gw_tmp = backbone_gw;
break;
}
rcu_read_unlock();
return backbone_gw_tmp;
}
void jump_label_inc(struct jump_label_key *key)
{
if (atomic_inc_not_zero(&key->enabled))
return;
jump_label_lock();
if (atomic_add_return(1, &key->enabled) == 1)
jump_label_update(key, JUMP_LABEL_ENABLE);
jump_label_unlock();
}
struct nouveau_channel *
nouveau_channel_get_unlocked(struct nouveau_channel *ref)
{
struct nouveau_channel *chan = NULL;
if (likely(ref && atomic_inc_not_zero(&ref->users)))
nouveau_channel_ref(ref, &chan);
return chan;
}
static struct ip6_flowlabel *fl_lookup(struct net *net, __be32 label)
{
struct ip6_flowlabel *fl;
rcu_read_lock_bh();
fl = __fl_lookup(net, label);
if (fl && !atomic_inc_not_zero(&fl->users))
fl = NULL;
rcu_read_unlock_bh();
return fl;
}
void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
{
CHECK_SLAB_OKAY(&local->usage);
if (!atomic_inc_not_zero(&local->usage)) {
printk("resurrected on reject\n");
BUG();
}
skb_queue_tail(&local->reject_queue, skb);
rxrpc_queue_work(&local->rejecter);
}
int
linux_alloc_current(struct thread *td, int flags)
{
struct proc *proc;
struct thread *td_other;
struct task_struct *ts;
struct task_struct *ts_other;
struct mm_struct *mm;
struct mm_struct *mm_other;
MPASS(td->td_lkpi_task == NULL);
ts = malloc(sizeof(*ts), M_LINUX_CURRENT, flags | M_ZERO);
if (ts == NULL)
return (ENOMEM);
mm = malloc(sizeof(*mm), M_LINUX_CURRENT, flags | M_ZERO);
if (mm == NULL) {
free(ts, M_LINUX_CURRENT);
return (ENOMEM);
}
/* setup new task structure */
atomic_set(&ts->kthread_flags, 0);
ts->task_thread = td;
ts->comm = td->td_name;
ts->pid = td->td_tid;
atomic_set(&ts->usage, 1);
atomic_set(&ts->state, TASK_RUNNING);
init_completion(&ts->parked);
init_completion(&ts->exited);
proc = td->td_proc;
/* check if another thread already has a mm_struct */
PROC_LOCK(proc);
FOREACH_THREAD_IN_PROC(proc, td_other) {
ts_other = td_other->td_lkpi_task;
if (ts_other == NULL)
continue;
mm_other = ts_other->mm;
if (mm_other == NULL)
continue;
/* try to share other mm_struct */
if (atomic_inc_not_zero(&mm_other->mm_users)) {
/* set mm_struct pointer */
ts->mm = mm_other;
break;
}
}
static struct nfulnl_instance *
instance_lookup_get(u_int16_t group_num)
{
struct nfulnl_instance *inst;
rcu_read_lock_bh();
inst = __instance_lookup(group_num);
if (inst && !atomic_inc_not_zero(&inst->use))
inst = NULL;
rcu_read_unlock_bh();
return inst;
}
/*
* Lookup a deviceid in cache and get a reference count on it if found
*
* @clp nfs_client associated with deviceid
* @id deviceid to look up
*/
struct nfs4_deviceid_node *
_find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
const struct nfs_client *clp, const struct nfs4_deviceid *id,
long hash)
{
struct nfs4_deviceid_node *d;
rcu_read_lock();
d = _lookup_deviceid(ld, clp, id, hash);
if (d && !atomic_inc_not_zero(&d->ref))
d = NULL;
rcu_read_unlock();
return d;
}
void static_key_slow_inc(struct static_key *key)
{
if (atomic_inc_not_zero(&key->enabled))
return;
jump_label_lock();
if (atomic_read(&key->enabled) == 0) {
if (!jump_label_get_branch_default(key))
jump_label_update(key, JUMP_LABEL_ENABLE);
else
jump_label_update(key, JUMP_LABEL_DISABLE);
}
atomic_inc(&key->enabled);
jump_label_unlock();
}
/**
* talitos_submit - submits a descriptor to the device for processing
* @dev: the SEC device to be used
* @desc: the descriptor to be processed by the device
* @callback: whom to call when processing is complete
* @context: a handle for use by caller (optional)
*
* desc must contain valid dma-mapped (bus physical) address pointers.
* callback must check err and feedback in descriptor header
* for device processing status.
*/
static int talitos_submit(struct device *dev, struct talitos_desc *desc,
void (*callback)(struct device *dev,
struct talitos_desc *desc,
void *context, int error),
void *context)
{
struct talitos_private *priv = dev_get_drvdata(dev);
struct talitos_request *request;
unsigned long flags, ch;
int head;
/* select done notification */
desc->hdr |= DESC_HDR_DONE_NOTIFY;
/* emulate SEC's round-robin channel fifo polling scheme */
ch = atomic_inc_return(&priv->last_chan) & (priv->num_channels - 1);
spin_lock_irqsave(&priv->head_lock[ch], flags);
if (!atomic_inc_not_zero(&priv->submit_count[ch])) {
/* h/w fifo is full */
spin_unlock_irqrestore(&priv->head_lock[ch], flags);
return -EAGAIN;
}
head = priv->head[ch];
request = &priv->fifo[ch][head];
/* map descriptor and save caller data */
request->dma_desc = dma_map_single(dev, desc, sizeof(*desc),
DMA_BIDIRECTIONAL);
request->callback = callback;
request->context = context;
/* increment fifo head */
priv->head[ch] = (priv->head[ch] + 1) & (priv->fifo_len - 1);
smp_wmb();
request->desc = desc;
/* GO! */
wmb();
out_be32(priv->reg + TALITOS_FF_LO(ch), request->dma_desc);
spin_unlock_irqrestore(&priv->head_lock[ch], flags);
return -EINPROGRESS;
}
//====================================================================
// Iterator function for adding an entry to the super block map for
// each ext2 file system.
static void build_super_block_map_iter_fn (struct super_block *sb, void *arg) {
if (num_super_blocks >= kSuperBlockLimit) {
DBG("Hit limit of %d file systems", kSuperBlockLimit);
return;
}
// Attempt to obtain a reference to this file system's super block.
if (!atomic_inc_not_zero(&sb->s_active)) {
DBG("Couldn't increment s_active for %s", sb->s_id);
return;
}
// Add the super block to the map.
super_block_map[num_super_blocks++] = sb;
DBG("Adding mapping %d -> %s", num_super_blocks, sb->s_id);
}
struct posix_acl *get_cached_acl(struct inode *inode, int type)
{
struct posix_acl **p = acl_by_type(inode, type);
struct posix_acl *acl;
for (;;) {
rcu_read_lock();
acl = rcu_dereference(*p);
if (!acl || is_uncached_acl(acl) ||
atomic_inc_not_zero(&acl->a_refcount))
break;
rcu_read_unlock();
cpu_relax();
}
rcu_read_unlock();
return acl;
}
static void *m_start(struct seq_file *m, loff_t *ppos)
{
struct proc_maps_private *priv = m->private;
unsigned long last_addr = m->version;
struct mm_struct *mm;
struct vm_area_struct *vma;
unsigned int pos = *ppos;
/* See m_cache_vma(). Zero at the start or after lseek. */
if (last_addr == -1UL)
return NULL;
priv->task = get_proc_task(priv->inode);
if (!priv->task)
return ERR_PTR(-ESRCH);
mm = priv->mm;
if (!mm || !atomic_inc_not_zero(&mm->mm_users))
return NULL;
down_read(&mm->mmap_sem);
hold_task_mempolicy(priv);
priv->tail_vma = get_gate_vma(mm);
if (last_addr) {
vma = find_vma(mm, last_addr);
if (vma && (vma = m_next_vma(priv, vma)))
return vma;
}
m->version = 0;
if (pos < mm->map_count) {
for (vma = mm->mmap; pos; pos--) {
m->version = vma->vm_start;
vma = vma->vm_next;
}
return vma;
}
/* we do not bother to update m->version in this case */
if (pos == mm->map_count && priv->tail_vma)
return priv->tail_vma;
vma_stop(priv);
return NULL;
}
/**
* batadv_choose_next_candidate - select the next DHT candidate
* @bat_priv: the bat priv with all the soft interface information
* @cands: candidates array
* @select: number of candidates already present in the array
* @ip_key: key to look up in the DHT
* @last_max: pointer where the address of the selected candidate will be saved
*/
static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
struct batadv_dat_candidate *cands,
int select, batadv_dat_addr_t ip_key,
batadv_dat_addr_t *last_max)
{
batadv_dat_addr_t max = 0, tmp_max = 0;
struct batadv_orig_node *orig_node, *max_orig_node = NULL;
struct batadv_hashtable *hash = bat_priv->orig_hash;
struct hlist_node *node;
struct hlist_head *head;
int i;
/* if no node is eligible as candidate, leave the candidate type as
* NOT_FOUND
*/
cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
/* iterate over the originator list and find the node with closest
* dat_address which has not been selected yet
*/
for (i = 0; i < hash->size; i++) {
head = &hash->table[i];
rcu_read_lock();
hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
/* the dht space is a ring and addresses are unsigned */
tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
ip_key;
if (!batadv_is_orig_node_eligible(cands, select,
tmp_max, max,
*last_max, orig_node,
max_orig_node))
continue;
if (!atomic_inc_not_zero(&orig_node->refcount))
continue;
max = tmp_max;
if (max_orig_node)
batadv_orig_node_free_ref(max_orig_node);
max_orig_node = orig_node;
}
rcu_read_unlock();
}
static struct rtable *tunnel_rtable_get(struct ip_tunnel *t, u32 cookie)
{
struct dst_entry *dst;
rcu_read_lock();
dst = rcu_dereference(this_cpu_ptr(t->dst_cache)->dst);
if (dst && !atomic_inc_not_zero(&dst->__refcnt))
dst = NULL;
if (dst) {
if (dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
tunnel_dst_reset(t);
dst_release(dst);
dst = NULL;
}
}
rcu_read_unlock();
return (struct rtable *)dst;
}
/* 获取缓存socket的HOOK函数 */
static unsigned int ipv4_conntrack_restore_sock (unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
struct nf_conntrack_ext *exts;
ct = nf_ct_get(skb, &ctinfo);
if (!ct || ct == &nf_conntrack_untracked){
goto out;
}
if ((ip_hdr(skb)->protocol != IPPROTO_UDP) &&
(ip_hdr(skb)->protocol != IPPROTO_TCP)) {
goto out;
}
exts = nf_conn_exts_find(ct);
if (exts) {
/* 获取缓存的socket */
if (exts->bits_idx[CONN_SOCK] != -1) {
struct sock *sk = (struct sock *)nf_ct_exts_get(ct, exts->bits_idx[CONN_SOCK]);
if (sk) {
if ((ip_hdr(skb)->protocol == IPPROTO_TCP) && sk->sk_state != TCP_ESTABLISHED) {
goto out;
}
if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
goto out;
}
skb_orphan(skb);
skb->sk = sk;
/* 曾经在上面atomic inc了引用计数，等到转交给下任owner的时候，一定要put */
skb->destructor = nf_ext_destructor;
}
}
}
out:
return NF_ACCEPT;
}
static struct rtable *tunnel_rtable_get(struct ip_tunnel *t,
u32 cookie, __be32 *saddr)
{
struct ip_tunnel_dst *idst;
struct dst_entry *dst;
rcu_read_lock();
idst = raw_cpu_ptr(t->dst_cache);
dst = rcu_dereference(idst->dst);
if (dst && !atomic_inc_not_zero(&dst->__refcnt))
dst = NULL;
if (dst) {
if (!dst->obsolete || dst->ops->check(dst, cookie)) {
*saddr = idst->saddr;
} else {
tunnel_dst_reset(t);
dst_release(dst);
dst = NULL;
}
}
rcu_read_unlock();
return (struct rtable *)dst;
}
void skb_clone_tx_timestamp(struct sk_buff *skb)
{
struct phy_device *phydev;
struct sk_buff *clone;
struct sock *sk = skb->sk;
unsigned int type;
if (!sk)
return;
type = classify(skb);
switch (type) {
case PTP_CLASS_V1_IPV4:
case PTP_CLASS_V1_IPV6:
case PTP_CLASS_V2_IPV4:
case PTP_CLASS_V2_IPV6:
case PTP_CLASS_V2_L2:
case PTP_CLASS_V2_VLAN:
phydev = skb->dev->phydev;
if (likely(phydev->drv->txtstamp)) {
if (!atomic_inc_not_zero(&sk->sk_refcnt))
return;
clone = skb_clone(skb, GFP_ATOMIC);
if (!clone) {
sock_put(sk);
return;
}
clone->sk = sk;
phydev->drv->txtstamp(phydev, clone, type);
}
break;
default:
break;
}
}
/*
* For each partition that XPC has established communications with, there is
* a minimum of one kernel thread assigned to perform any operation that
* may potentially sleep or block (basically the callouts to the asynchronous
* functions registered via xpc_connect()).
*
* Additional kthreads are created and destroyed by XPC as the workload
* demands.
*
* A kthread is assigned to one of the active channels that exists for a given
* partition.
*/
void
xpc_create_kthreads(struct xpc_channel *ch, int needed,
int ignore_disconnecting)
{
unsigned long irq_flags;
u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
struct xpc_partition *part = &xpc_partitions[ch->partid];
struct task_struct *kthread;
while (needed-- > 0) {
/*
* The following is done on behalf of the newly created
* kthread. That kthread is responsible for doing the
* counterpart to the following before it exits.
*/
if (ignore_disconnecting) {
if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
/* kthreads assigned had gone to zero */
BUG_ON(!(ch->flags &
XPC_C_DISCONNECTINGCALLOUT_MADE));
break;
}
} else if (ch->flags & XPC_C_DISCONNECTING) {
break;
} else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
atomic_inc_return(&part->nchannels_engaged) == 1) {
xpc_indicate_partition_engaged(part);
}
(void)xpc_part_ref(part);
xpc_msgqueue_ref(ch);
kthread = kthread_run(xpc_kthread_start, (void *)args,
"xpc%02dc%d", ch->partid, ch->number);
if (IS_ERR(kthread)) {
/* the fork failed */
/*
* NOTE: if (ignore_disconnecting &&
* !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
* then we'll deadlock if all other kthreads assigned
* to this channel are blocked in the channel's
* registerer, because the only thing that will unblock
* them is the xpDisconnecting callout that this
* failed kthread_run() would have made.
*/
if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
atomic_dec_return(&part->nchannels_engaged) == 0) {
xpc_indicate_partition_disengaged(part);
}
xpc_msgqueue_deref(ch);
xpc_part_deref(part);
if (atomic_read(&ch->kthreads_assigned) <
ch->kthreads_idle_limit) {
/*
* Flag this as an error only if we have an
* insufficient #of kthreads for the channel
* to function.
*/
spin_lock_irqsave(&ch->lock, irq_flags);
XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
&irq_flags);
spin_unlock_irqrestore(&ch->lock, irq_flags);
}
break;
}
}
}
void
xpc_create_kthreads(struct xpc_channel *ch, int needed,
int ignore_disconnecting)
{
unsigned long irq_flags;
u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
struct xpc_partition *part = &xpc_partitions[ch->partid];
struct task_struct *kthread;
void (*indicate_partition_disengaged) (struct xpc_partition *) =
xpc_arch_ops.indicate_partition_disengaged;
while (needed-- > 0) {
/*
*/
if (ignore_disconnecting) {
if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
/* */
BUG_ON(!(ch->flags &
XPC_C_DISCONNECTINGCALLOUT_MADE));
break;
}
} else if (ch->flags & XPC_C_DISCONNECTING) {
break;
} else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
atomic_inc_return(&part->nchannels_engaged) == 1) {
xpc_arch_ops.indicate_partition_engaged(part);
}
(void)xpc_part_ref(part);
xpc_msgqueue_ref(ch);
kthread = kthread_run(xpc_kthread_start, (void *)args,
"xpc%02dc%d", ch->partid, ch->number);
if (IS_ERR(kthread)) {
/* */
/*
*/
if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
atomic_dec_return(&part->nchannels_engaged) == 0) {
indicate_partition_disengaged(part);
}
xpc_msgqueue_deref(ch);
xpc_part_deref(part);
if (atomic_read(&ch->kthreads_assigned) <
ch->kthreads_idle_limit) {
/*
*/
spin_lock_irqsave(&ch->lock, irq_flags);
XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
&irq_flags);
spin_unlock_irqrestore(&ch->lock, irq_flags);
}
break;
}
}
}
