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-rw-r--r--kernel/pid.c116
1 files changed, 73 insertions, 43 deletions
diff --git a/kernel/pid.c b/kernel/pid.c
index ce8e00deacc..9b9a2669814 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -1,8 +1,8 @@
/*
* Generic pidhash and scalable, time-bounded PID allocator
*
- * (C) 2002-2003 William Irwin, IBM
- * (C) 2004 William Irwin, Oracle
+ * (C) 2002-2003 Nadia Yvette Chambers, IBM
+ * (C) 2004 Nadia Yvette Chambers, Oracle
* (C) 2002-2004 Ingo Molnar, Red Hat
*
* pid-structures are backing objects for tasks sharing a given ID to chain
@@ -36,6 +36,8 @@
#include <linux/pid_namespace.h>
#include <linux/init_task.h>
#include <linux/syscalls.h>
+#include <linux/proc_ns.h>
+#include <linux/proc_fs.h>
#define pid_hashfn(nr, ns) \
hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
@@ -50,9 +52,6 @@ int pid_max = PID_MAX_DEFAULT;
int pid_max_min = RESERVED_PIDS + 1;
int pid_max_max = PID_MAX_LIMIT;
-#define BITS_PER_PAGE (PAGE_SIZE*8)
-#define BITS_PER_PAGE_MASK (BITS_PER_PAGE-1)
-
static inline int mk_pid(struct pid_namespace *pid_ns,
struct pidmap *map, int off)
{
@@ -76,26 +75,14 @@ struct pid_namespace init_pid_ns = {
[ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
},
.last_pid = 0,
+ .nr_hashed = PIDNS_HASH_ADDING,
.level = 0,
.child_reaper = &init_task,
+ .user_ns = &init_user_ns,
+ .proc_inum = PROC_PID_INIT_INO,
};
EXPORT_SYMBOL_GPL(init_pid_ns);
-int is_container_init(struct task_struct *tsk)
-{
- int ret = 0;
- struct pid *pid;
-
- rcu_read_lock();
- pid = task_pid(tsk);
- if (pid != NULL && pid->numbers[pid->level].nr == 1)
- ret = 1;
- rcu_read_unlock();
-
- return ret;
-}
-EXPORT_SYMBOL(is_container_init);
-
/*
* Note: disable interrupts while the pidmap_lock is held as an
* interrupt might come in and do read_lock(&tasklist_lock).
@@ -195,15 +182,19 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
break;
}
if (likely(atomic_read(&map->nr_free))) {
- do {
+ for ( ; ; ) {
if (!test_and_set_bit(offset, map->page)) {
atomic_dec(&map->nr_free);
set_last_pid(pid_ns, last, pid);
return pid;
}
offset = find_next_offset(map, offset);
+ if (offset >= BITS_PER_PAGE)
+ break;
pid = mk_pid(pid_ns, map, offset);
- } while (offset < BITS_PER_PAGE && pid < pid_max);
+ if (pid >= pid_max)
+ break;
+ }
}
if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) {
++map;
@@ -269,8 +260,29 @@ void free_pid(struct pid *pid)
unsigned long flags;
spin_lock_irqsave(&pidmap_lock, flags);
- for (i = 0; i <= pid->level; i++)
- hlist_del_rcu(&pid->numbers[i].pid_chain);
+ for (i = 0; i <= pid->level; i++) {
+ struct upid *upid = pid->numbers + i;
+ struct pid_namespace *ns = upid->ns;
+ hlist_del_rcu(&upid->pid_chain);
+ switch(--ns->nr_hashed) {
+ case 2:
+ case 1:
+ /* When all that is left in the pid namespace
+ * is the reaper wake up the reaper. The reaper
+ * may be sleeping in zap_pid_ns_processes().
+ */
+ wake_up_process(ns->child_reaper);
+ break;
+ case PIDNS_HASH_ADDING:
+ /* Handle a fork failure of the first process */
+ WARN_ON(ns->child_reaper);
+ ns->nr_hashed = 0;
+ /* fall through */
+ case 0:
+ schedule_work(&ns->proc_work);
+ break;
+ }
+ }
spin_unlock_irqrestore(&pidmap_lock, flags);
for (i = 0; i <= pid->level; i++)
@@ -292,6 +304,7 @@ struct pid *alloc_pid(struct pid_namespace *ns)
goto out;
tmp = ns;
+ pid->level = ns->level;
for (i = ns->level; i >= 0; i--) {
nr = alloc_pidmap(tmp);
if (nr < 0)
@@ -302,22 +315,32 @@ struct pid *alloc_pid(struct pid_namespace *ns)
tmp = tmp->parent;
}
+ if (unlikely(is_child_reaper(pid))) {
+ if (pid_ns_prepare_proc(ns))
+ goto out_free;
+ }
+
get_pid_ns(ns);
- pid->level = ns->level;
atomic_set(&pid->count, 1);
for (type = 0; type < PIDTYPE_MAX; ++type)
INIT_HLIST_HEAD(&pid->tasks[type]);
upid = pid->numbers + ns->level;
spin_lock_irq(&pidmap_lock);
- for ( ; upid >= pid->numbers; --upid)
+ if (!(ns->nr_hashed & PIDNS_HASH_ADDING))
+ goto out_unlock;
+ for ( ; upid >= pid->numbers; --upid) {
hlist_add_head_rcu(&upid->pid_chain,
&pid_hash[pid_hashfn(upid->nr, upid->ns)]);
+ upid->ns->nr_hashed++;
+ }
spin_unlock_irq(&pidmap_lock);
out:
return pid;
+out_unlock:
+ spin_unlock_irq(&pidmap_lock);
out_free:
while (++i <= ns->level)
free_pidmap(pid->numbers + i);
@@ -327,12 +350,18 @@ out_free:
goto out;
}
+void disable_pid_allocation(struct pid_namespace *ns)
+{
+ spin_lock_irq(&pidmap_lock);
+ ns->nr_hashed &= ~PIDNS_HASH_ADDING;
+ spin_unlock_irq(&pidmap_lock);
+}
+
struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
{
- struct hlist_node *elem;
struct upid *pnr;
- hlist_for_each_entry_rcu(pnr, elem,
+ hlist_for_each_entry_rcu(pnr,
&pid_hash[pid_hashfn(nr, ns)], pid_chain)
if (pnr->nr == nr && pnr->ns == ns)
return container_of(pnr, struct pid,
@@ -344,21 +373,17 @@ EXPORT_SYMBOL_GPL(find_pid_ns);
struct pid *find_vpid(int nr)
{
- return find_pid_ns(nr, current->nsproxy->pid_ns);
+ return find_pid_ns(nr, task_active_pid_ns(current));
}
EXPORT_SYMBOL_GPL(find_vpid);
/*
* attach_pid() must be called with the tasklist_lock write-held.
*/
-void attach_pid(struct task_struct *task, enum pid_type type,
- struct pid *pid)
+void attach_pid(struct task_struct *task, enum pid_type type)
{
- struct pid_link *link;
-
- link = &task->pids[type];
- link->pid = pid;
- hlist_add_head_rcu(&link->node, &pid->tasks[type]);
+ struct pid_link *link = &task->pids[type];
+ hlist_add_head_rcu(&link->node, &link->pid->tasks[type]);
}
static void __change_pid(struct task_struct *task, enum pid_type type,
@@ -390,7 +415,7 @@ void change_pid(struct task_struct *task, enum pid_type type,
struct pid *pid)
{
__change_pid(task, type, pid);
- attach_pid(task, type, pid);
+ attach_pid(task, type);
}
/* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
@@ -428,7 +453,7 @@ struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
struct task_struct *find_task_by_vpid(pid_t vnr)
{
- return find_task_by_pid_ns(vnr, current->nsproxy->pid_ns);
+ return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
}
struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
@@ -479,10 +504,11 @@ pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
}
return nr;
}
+EXPORT_SYMBOL_GPL(pid_nr_ns);
pid_t pid_vnr(struct pid *pid)
{
- return pid_nr_ns(pid, current->nsproxy->pid_ns);
+ return pid_nr_ns(pid, task_active_pid_ns(current));
}
EXPORT_SYMBOL_GPL(pid_vnr);
@@ -493,7 +519,7 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
rcu_read_lock();
if (!ns)
- ns = current->nsproxy->pid_ns;
+ ns = task_active_pid_ns(current);
if (likely(pid_alive(task))) {
if (type != PIDTYPE_PID)
task = task->group_leader;
@@ -543,12 +569,13 @@ struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
*/
void __init pidhash_init(void)
{
- int i, pidhash_size;
+ unsigned int i, pidhash_size;
pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18,
HASH_EARLY | HASH_SMALL,
- &pidhash_shift, NULL, 4096);
- pidhash_size = 1 << pidhash_shift;
+ &pidhash_shift, NULL,
+ 0, 4096);
+ pidhash_size = 1U << pidhash_shift;
for (i = 0; i < pidhash_size; i++)
INIT_HLIST_HEAD(&pid_hash[i]);
@@ -556,6 +583,9 @@ void __init pidhash_init(void)
void __init pidmap_init(void)
{
+ /* Veryify no one has done anything silly */
+ BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_HASH_ADDING);
+
/* bump default and minimum pid_max based on number of cpus */
pid_max = min(pid_max_max, max_t(int, pid_max,
PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-11-09 20:39:57 +0000