static unsigned __read_mostly afs_cell_gc_delay = 10;
static unsigned __read_mostly afs_cell_min_ttl = 10 * 60;
static unsigned __read_mostly afs_cell_max_ttl = 24 * 60 * 60;
+static atomic_t cell_debug_id;
-static void afs_manage_cell(struct work_struct *);
+static void afs_queue_cell_manager(struct afs_net *);
+static void afs_manage_cell_work(struct work_struct *);
static void afs_dec_cells_outstanding(struct afs_net *net)
{
atomic_inc(&net->cells_outstanding);
if (timer_reduce(&net->cells_timer, jiffies + delay * HZ))
afs_dec_cells_outstanding(net);
+ } else {
+ afs_queue_cell_manager(net);
}
}
/*
- * Look up and get an activation reference on a cell record under RCU
- * conditions. The caller must hold the RCU read lock.
+ * Look up and get an activation reference on a cell record. The caller must
+ * hold net->cells_lock at least read-locked.
*/
-struct afs_cell *afs_lookup_cell_rcu(struct afs_net *net,
- const char *name, unsigned int namesz)
+static struct afs_cell *afs_find_cell_locked(struct afs_net *net,
+ const char *name, unsigned int namesz,
+ enum afs_cell_trace reason)
{
struct afs_cell *cell = NULL;
struct rb_node *p;
- int n, seq = 0, ret = 0;
+ int n;
_enter("%*.*s", namesz, namesz, name);
if (namesz > AFS_MAXCELLNAME)
return ERR_PTR(-ENAMETOOLONG);
- do {
- /* Unfortunately, rbtree walking doesn't give reliable results
- * under just the RCU read lock, so we have to check for
- * changes.
- */
- if (cell)
- afs_put_cell(net, cell);
- cell = NULL;
- ret = -ENOENT;
-
- read_seqbegin_or_lock(&net->cells_lock, &seq);
-
- if (!name) {
- cell = rcu_dereference_raw(net->ws_cell);
- if (cell) {
- afs_get_cell(cell);
- ret = 0;
- break;
- }
- ret = -EDESTADDRREQ;
- continue;
- }
+ if (!name) {
+ cell = net->ws_cell;
+ if (!cell)
+ return ERR_PTR(-EDESTADDRREQ);
+ goto found;
+ }
- p = rcu_dereference_raw(net->cells.rb_node);
- while (p) {
- cell = rb_entry(p, struct afs_cell, net_node);
-
- n = strncasecmp(cell->name, name,
- min_t(size_t, cell->name_len, namesz));
- if (n == 0)
- n = cell->name_len - namesz;
- if (n < 0) {
- p = rcu_dereference_raw(p->rb_left);
- } else if (n > 0) {
- p = rcu_dereference_raw(p->rb_right);
- } else {
- if (atomic_inc_not_zero(&cell->usage)) {
- ret = 0;
- break;
- }
- /* We want to repeat the search, this time with
- * the lock properly locked.
- */
- }
- cell = NULL;
- }
+ p = net->cells.rb_node;
+ while (p) {
+ cell = rb_entry(p, struct afs_cell, net_node);
- } while (need_seqretry(&net->cells_lock, seq));
+ n = strncasecmp(cell->name, name,
+ min_t(size_t, cell->name_len, namesz));
+ if (n == 0)
+ n = cell->name_len - namesz;
+ if (n < 0)
+ p = p->rb_left;
+ else if (n > 0)
+ p = p->rb_right;
+ else
+ goto found;
+ }
- done_seqretry(&net->cells_lock, seq);
+ return ERR_PTR(-ENOENT);
- if (ret != 0 && cell)
- afs_put_cell(net, cell);
+found:
+ return afs_use_cell(cell, reason);
+}
- return ret == 0 ? cell : ERR_PTR(ret);
+/*
+ * Look up and get an activation reference on a cell record.
+ */
+struct afs_cell *afs_find_cell(struct afs_net *net,
+ const char *name, unsigned int namesz,
+ enum afs_cell_trace reason)
+{
+ struct afs_cell *cell;
+
+ down_read(&net->cells_lock);
+ cell = afs_find_cell_locked(net, name, namesz, reason);
+ up_read(&net->cells_lock);
+ return cell;
}
/*
cell->name[i] = tolower(name[i]);
cell->name[i] = 0;
- atomic_set(&cell->usage, 2);
- INIT_WORK(&cell->manager, afs_manage_cell);
+ atomic_set(&cell->ref, 1);
+ atomic_set(&cell->active, 0);
+ INIT_WORK(&cell->manager, afs_manage_cell_work);
cell->volumes = RB_ROOT;
INIT_HLIST_HEAD(&cell->proc_volumes);
seqlock_init(&cell->volume_lock);
cell->dns_source = vllist->source;
cell->dns_status = vllist->status;
smp_store_release(&cell->dns_lookup_count, 1); /* vs source/status */
+ atomic_inc(&net->cells_outstanding);
+ cell->debug_id = atomic_inc_return(&cell_debug_id);
+ trace_afs_cell(cell->debug_id, 1, 0, afs_cell_trace_alloc);
_leave(" = %p", cell);
return cell;
_enter("%s,%s", name, vllist);
if (!excl) {
- rcu_read_lock();
- cell = afs_lookup_cell_rcu(net, name, namesz);
- rcu_read_unlock();
+ cell = afs_find_cell(net, name, namesz, afs_cell_trace_use_lookup);
if (!IS_ERR(cell))
goto wait_for_cell;
}
/* Find the insertion point and check to see if someone else added a
* cell whilst we were allocating.
*/
- write_seqlock(&net->cells_lock);
+ down_write(&net->cells_lock);
pp = &net->cells.rb_node;
parent = NULL;
cell = candidate;
candidate = NULL;
+ atomic_set(&cell->active, 2);
+ trace_afs_cell(cell->debug_id, atomic_read(&cell->ref), 2, afs_cell_trace_insert);
rb_link_node_rcu(&cell->net_node, parent, pp);
rb_insert_color(&cell->net_node, &net->cells);
- atomic_inc(&net->cells_outstanding);
- write_sequnlock(&net->cells_lock);
+ up_write(&net->cells_lock);
- queue_work(afs_wq, &cell->manager);
+ afs_queue_cell(cell, afs_cell_trace_get_queue_new);
wait_for_cell:
+ trace_afs_cell(cell->debug_id, atomic_read(&cell->ref), atomic_read(&cell->active),
+ afs_cell_trace_wait);
_debug("wait_for_cell");
wait_var_event(&cell->state,
({
state = smp_load_acquire(&cell->state); /* vs error */
- state == AFS_CELL_ACTIVE || state == AFS_CELL_FAILED;
+ state == AFS_CELL_ACTIVE || state == AFS_CELL_REMOVED;
}));
/* Check the state obtained from the wait check. */
- if (state == AFS_CELL_FAILED) {
+ if (state == AFS_CELL_REMOVED) {
ret = cell->error;
goto error;
}
if (excl) {
ret = -EEXIST;
} else {
- afs_get_cell(cursor);
+ afs_use_cell(cursor, afs_cell_trace_use_lookup);
ret = 0;
}
- write_sequnlock(&net->cells_lock);
- kfree(candidate);
+ up_write(&net->cells_lock);
+ if (candidate)
+ afs_put_cell(candidate, afs_cell_trace_put_candidate);
if (ret == 0)
goto wait_for_cell;
goto error_noput;
error:
- afs_put_cell(net, cell);
+ afs_unuse_cell(net, cell, afs_cell_trace_unuse_lookup);
error_noput:
_leave(" = %d [error]", ret);
return ERR_PTR(ret);
}
if (!test_and_set_bit(AFS_CELL_FL_NO_GC, &new_root->flags))
- afs_get_cell(new_root);
+ afs_use_cell(new_root, afs_cell_trace_use_pin);
/* install the new cell */
- write_seqlock(&net->cells_lock);
- old_root = rcu_access_pointer(net->ws_cell);
- rcu_assign_pointer(net->ws_cell, new_root);
- write_sequnlock(&net->cells_lock);
+ down_write(&net->cells_lock);
+ afs_see_cell(new_root, afs_cell_trace_see_ws);
+ old_root = net->ws_cell;
+ net->ws_cell = new_root;
+ up_write(&net->cells_lock);
- afs_put_cell(net, old_root);
+ afs_unuse_cell(net, old_root, afs_cell_trace_unuse_ws);
_leave(" = 0");
return 0;
}
static void afs_cell_destroy(struct rcu_head *rcu)
{
struct afs_cell *cell = container_of(rcu, struct afs_cell, rcu);
+ struct afs_net *net = cell->net;
+ int u;
_enter("%p{%s}", cell, cell->name);
- ASSERTCMP(atomic_read(&cell->usage), ==, 0);
+ u = atomic_read(&cell->ref);
+ ASSERTCMP(u, ==, 0);
+ trace_afs_cell(cell->debug_id, u, atomic_read(&cell->active), afs_cell_trace_free);
- afs_put_volume(cell->net, cell->root_volume, afs_volume_trace_put_cell_root);
- afs_put_vlserverlist(cell->net, rcu_access_pointer(cell->vl_servers));
- afs_put_cell(cell->net, cell->alias_of);
+ afs_put_vlserverlist(net, rcu_access_pointer(cell->vl_servers));
+ afs_unuse_cell(net, cell->alias_of, afs_cell_trace_unuse_alias);
key_put(cell->anonymous_key);
kfree(cell->name);
kfree(cell);
+ afs_dec_cells_outstanding(net);
_leave(" [destroyed]");
}
/*
* Get a reference on a cell record.
*/
-struct afs_cell *afs_get_cell(struct afs_cell *cell)
+struct afs_cell *afs_get_cell(struct afs_cell *cell, enum afs_cell_trace reason)
{
- atomic_inc(&cell->usage);
+ int u;
+
+ if (atomic_read(&cell->ref) <= 0)
+ BUG();
+
+ u = atomic_inc_return(&cell->ref);
+ trace_afs_cell(cell->debug_id, u, atomic_read(&cell->active), reason);
return cell;
}
/*
* Drop a reference on a cell record.
*/
-void afs_put_cell(struct afs_net *net, struct afs_cell *cell)
+void afs_put_cell(struct afs_cell *cell, enum afs_cell_trace reason)
{
+ if (cell) {
+ unsigned int debug_id = cell->debug_id;
+ unsigned int u, a;
+
+ a = atomic_read(&cell->active);
+ u = atomic_dec_return(&cell->ref);
+ trace_afs_cell(debug_id, u, a, reason);
+ if (u == 0) {
+ a = atomic_read(&cell->active);
+ WARN(a != 0, "Cell active count %u > 0\n", a);
+ call_rcu(&cell->rcu, afs_cell_destroy);
+ }
+ }
+}
+
+/*
+ * Note a cell becoming more active.
+ */
+struct afs_cell *afs_use_cell(struct afs_cell *cell, enum afs_cell_trace reason)
+{
+ int u, a;
+
+ if (atomic_read(&cell->ref) <= 0)
+ BUG();
+
+ u = atomic_read(&cell->ref);
+ a = atomic_inc_return(&cell->active);
+ trace_afs_cell(cell->debug_id, u, a, reason);
+ return cell;
+}
+
+/*
+ * Record a cell becoming less active. When the active counter reaches 1, it
+ * is scheduled for destruction, but may get reactivated.
+ */
+void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell, enum afs_cell_trace reason)
+{
+ unsigned int debug_id;
time64_t now, expire_delay;
+ int u, a;
if (!cell)
return;
if (cell->vl_servers->nr_servers)
expire_delay = afs_cell_gc_delay;
- if (atomic_dec_return(&cell->usage) > 1)
- return;
+ debug_id = cell->debug_id;
+ u = atomic_read(&cell->ref);
+ a = atomic_dec_return(&cell->active);
+ trace_afs_cell(debug_id, u, a, reason);
+ WARN_ON(a == 0);
+ if (a == 1)
+ /* 'cell' may now be garbage collected. */
+ afs_set_cell_timer(net, expire_delay);
+}
+
+/*
+ * Note that a cell has been seen.
+ */
+void afs_see_cell(struct afs_cell *cell, enum afs_cell_trace reason)
+{
+ int u, a;
+
+ u = atomic_read(&cell->ref);
+ a = atomic_read(&cell->active);
+ trace_afs_cell(cell->debug_id, u, a, reason);
+}
- /* 'cell' may now be garbage collected. */
- afs_set_cell_timer(net, expire_delay);
+/*
+ * Queue a cell for management, giving the workqueue a ref to hold.
+ */
+void afs_queue_cell(struct afs_cell *cell, enum afs_cell_trace reason)
+{
+ afs_get_cell(cell, reason);
+ if (!queue_work(afs_wq, &cell->manager))
+ afs_put_cell(cell, afs_cell_trace_put_queue_fail);
}
/*
* Manage a cell record, initialising and destroying it, maintaining its DNS
* records.
*/
-static void afs_manage_cell(struct work_struct *work)
+static void afs_manage_cell(struct afs_cell *cell)
{
- struct afs_cell *cell = container_of(work, struct afs_cell, manager);
struct afs_net *net = cell->net;
- bool deleted;
- int ret, usage;
+ int ret, active;
_enter("%s", cell->name);
switch (cell->state) {
case AFS_CELL_INACTIVE:
case AFS_CELL_FAILED:
- write_seqlock(&net->cells_lock);
- usage = 1;
- deleted = atomic_try_cmpxchg_relaxed(&cell->usage, &usage, 0);
- if (deleted)
+ down_write(&net->cells_lock);
+ active = 1;
+ if (atomic_try_cmpxchg_relaxed(&cell->active, &active, 0)) {
rb_erase(&cell->net_node, &net->cells);
- write_sequnlock(&net->cells_lock);
- if (deleted)
+ trace_afs_cell(cell->debug_id, atomic_read(&cell->ref), 0,
+ afs_cell_trace_unuse_delete);
+ smp_store_release(&cell->state, AFS_CELL_REMOVED);
+ }
+ up_write(&net->cells_lock);
+ if (cell->state == AFS_CELL_REMOVED) {
+ wake_up_var(&cell->state);
goto final_destruction;
+ }
if (cell->state == AFS_CELL_FAILED)
goto done;
smp_store_release(&cell->state, AFS_CELL_UNSET);
goto again;
case AFS_CELL_ACTIVE:
- if (atomic_read(&cell->usage) > 1) {
+ if (atomic_read(&cell->active) > 1) {
if (test_and_clear_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags)) {
ret = afs_update_cell(cell);
if (ret < 0)
goto again;
case AFS_CELL_DEACTIVATING:
- if (atomic_read(&cell->usage) > 1)
+ if (atomic_read(&cell->active) > 1)
goto reverse_deactivation;
afs_deactivate_cell(net, cell);
smp_store_release(&cell->state, AFS_CELL_INACTIVE);
wake_up_var(&cell->state);
goto again;
+ case AFS_CELL_REMOVED:
+ goto done;
+
default:
break;
}
return;
final_destruction:
- call_rcu(&cell->rcu, afs_cell_destroy);
- afs_dec_cells_outstanding(net);
- _leave(" [destruct %d]", atomic_read(&net->cells_outstanding));
+ /* The root volume is pinning the cell */
+ afs_put_volume(cell->net, cell->root_volume, afs_volume_trace_put_cell_root);
+ cell->root_volume = NULL;
+ afs_put_cell(cell, afs_cell_trace_put_destroy);
+}
+
+static void afs_manage_cell_work(struct work_struct *work)
+{
+ struct afs_cell *cell = container_of(work, struct afs_cell, manager);
+
+ afs_manage_cell(cell);
+ afs_put_cell(cell, afs_cell_trace_put_queue_work);
}
/*
* lack of use and cells whose DNS results have expired and dispatch
* their managers.
*/
- read_seqlock_excl(&net->cells_lock);
+ down_read(&net->cells_lock);
for (cursor = rb_first(&net->cells); cursor; cursor = rb_next(cursor)) {
struct afs_cell *cell =
rb_entry(cursor, struct afs_cell, net_node);
- unsigned usage;
+ unsigned active;
bool sched_cell = false;
- usage = atomic_read(&cell->usage);
- _debug("manage %s %u", cell->name, usage);
+ active = atomic_read(&cell->active);
+ trace_afs_cell(cell->debug_id, atomic_read(&cell->ref),
+ active, afs_cell_trace_manage);
- ASSERTCMP(usage, >=, 1);
+ ASSERTCMP(active, >=, 1);
if (purging) {
- if (test_and_clear_bit(AFS_CELL_FL_NO_GC, &cell->flags))
- usage = atomic_dec_return(&cell->usage);
- ASSERTCMP(usage, ==, 1);
+ if (test_and_clear_bit(AFS_CELL_FL_NO_GC, &cell->flags)) {
+ active = atomic_dec_return(&cell->active);
+ trace_afs_cell(cell->debug_id, atomic_read(&cell->ref),
+ active, afs_cell_trace_unuse_pin);
+ }
}
- if (usage == 1) {
+ if (active == 1) {
struct afs_vlserver_list *vllist;
time64_t expire_at = cell->last_inactive;
}
if (sched_cell)
- queue_work(afs_wq, &cell->manager);
+ afs_queue_cell(cell, afs_cell_trace_get_queue_manage);
}
- read_sequnlock_excl(&net->cells_lock);
+ up_read(&net->cells_lock);
/* Update the timer on the way out. We have to pass an increment on
* cells_outstanding in the namespace that we are in to the timer or
_enter("");
- write_seqlock(&net->cells_lock);
- ws = rcu_access_pointer(net->ws_cell);
- RCU_INIT_POINTER(net->ws_cell, NULL);
- write_sequnlock(&net->cells_lock);
- afs_put_cell(net, ws);
+ down_write(&net->cells_lock);
+ ws = net->ws_cell;
+ net->ws_cell = NULL;
+ up_write(&net->cells_lock);
+ afs_unuse_cell(net, ws, afs_cell_trace_unuse_ws);
_debug("del timer");
if (del_timer_sync(&net->cells_timer))
projects / linux-2.6-microblaze.git / blobdiff