In pid_alloc function, idr_preload function is used along with
idr_alloc_cyclic.
idr_alloc_cyclic is used instead of idr_alloc because we might want to
reuse the unassigned integers. The rest of the code is same as the previous
alloc_pid, which puts the pid allocated onto the task list. After the flag
out_free, ids are removed from the idr entry using idr_remove function.
Inside free_pid() deleting from rcu hash list is same as before.
The only change is instead of removing entry from pidmap, allocated
number is now deleted from the idr entry.
Signed-off-by: Gargi Sharma <gs051095@xxxxxxxxx>
---
kernel/pid.c | 26 +++++++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)
diff --git a/kernel/pid.c b/kernel/pid.c
index fd1cde1..5060266 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -287,8 +287,14 @@ void free_pid(struct pid *pid)
}
spin_unlock_irqrestore(&pidmap_lock, flags);
- for (i = 0; i <= pid->level; i++)
- free_pidmap(pid->numbers + i);
+ for (i = 0; i <= pid->level; i++) {
+ struct upid *upid = pid->numbers + i;
+ struct pid_namespace *ns = upid->ns;
+
+ mutex_lock(&ns->idr_mutex_lock);
+ idr_remove(ns->idr, upid->nr);
+ mutex_unlock(&ns->idr_mutex_lock);
+ }
call_rcu(&pid->rcu, delayed_put_pid);
}
@@ -309,7 +315,15 @@ struct pid *alloc_pid(struct pid_namespace *ns)
tmp = ns;
pid->level = ns->level;
for (i = ns->level; i >= 0; i--) {
- nr = alloc_pidmap(tmp);
+ idr_preload(GFP_KERNEL);
+
+ mutex_lock(&ns->idr_mutex_lock);
+ nr = idr_alloc_cyclic(tmp->idr, ns, RESERVED_PIDS,
+ pid_max, GFP_KERNEL);
+
+ mutex_unlock(&ns->idr_mutex_lock);
+ idr_preload_end();
+
if (nr < 0) {
retval = nr;
goto out_free;
@@ -350,8 +364,10 @@ struct pid *alloc_pid(struct pid_namespace *ns)
put_pid_ns(ns);
out_free:
- while (++i <= ns->level)
- free_pidmap(pid->numbers + i);
+ while (++i <= ns->level) {
+ idr_remove(ns->idr, (pid->numbers + i)->nr);
+ mutex_unlock(&ns->idr_mutex_lock);
+ }
kmem_cache_free(ns->pid_cachep, pid);
return ERR_PTR(retval);
--
2.7.4
--
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