1 files changed, 19 insertions, 23 deletions

diff --git a/ipc/util.c b/ipc/util.c
index 72fd0785ac94..464a8abd779f 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -122,6 +122,7 @@ void ipc_init_ids(struct ipc_ids *ids)
 
         ids->in_use = 0;
         ids->seq = 0;
+        ids->next_id = -1;
         {
                 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
                 if (seq_limit > USHRT_MAX)
@@ -251,7 +252,8 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 {
         kuid_t euid;
         kgid_t egid;
-        int id, err;
+        int id;
+        int next_id = ids->next_id;
 
         if (size > IPCMNI)
                 size = IPCMNI;
@@ -259,16 +261,21 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
         if (ids->in_use >= size)
                 return -ENOSPC;
 
+        idr_preload(GFP_KERNEL);
+
         spin_lock_init(&new->lock);
         new->deleted = 0;
         rcu_read_lock();
         spin_lock(&new->lock);
 
-        err = idr_get_new(&ids->ipcs_idr, new, &id);
-        if (err) {
+        id = idr_alloc(&ids->ipcs_idr, new,
+                       (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
+                       GFP_NOWAIT);
+        idr_preload_end();
+        if (id < 0) {
                 spin_unlock(&new->lock);
                 rcu_read_unlock();
-                return err;
+                return id;
         }
 
         ids->in_use++;
@@ -277,9 +284,14 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
         new->cuid = new->uid = euid;
         new->gid = new->cgid = egid;
 
-        new->seq = ids->seq++;
-        if(ids->seq > ids->seq_max)
-                ids->seq = 0;
+        if (next_id < 0) {
+                new->seq = ids->seq++;
+                if (ids->seq > ids->seq_max)
+                        ids->seq = 0;
+        } else {
+                new->seq = ipcid_to_seqx(next_id);
+                ids->next_id = -1;
+        }
 
         new->id = ipc_buildid(id, new->seq);
         return id;
@@ -299,19 +311,10 @@ static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
                 struct ipc_ops *ops, struct ipc_params *params)
 {
         int err;
-retry:
-        err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
-
-        if (!err)
-                return -ENOMEM;
 
         down_write(&ids->rw_mutex);
         err = ops->getnew(ns, params);
         up_write(&ids->rw_mutex);
-
-        if (err == -EAGAIN)
-                goto retry;
-
         return err;
 }
 
@@ -368,8 +371,6 @@ static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
         struct kern_ipc_perm *ipcp;
         int flg = params->flg;
         int err;
-retry:
-        err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
 
         /*
          * Take the lock as a writer since we are potentially going to add
@@ -381,8 +382,6 @@ retry:
                 /* key not used */
                 if (!(flg & IPC_CREAT))
                         err = -ENOENT;
-                else if (!err)
-                        err = -ENOMEM;
                 else
                         err = ops->getnew(ns, params);
         } else {
@@ -405,9 +404,6 @@ retry:
         }
         up_write(&ids->rw_mutex);
 
-        if (err == -EAGAIN)
-                goto retry;
-
         return err;
 }