ipc: convert to idr_alloc()

Convert to the much saner new idr interface.

The new interface doesn't directly translate to the way idr_pre_get()
was used around ipc_addid() as preloading disables preemption.  From
my cursory reading, it seems like we should be able to do all
allocation from ipc_addid(), so I moved it there.  Can you please
check whether this would be okay?  If this is wrong and ipc_addid()
should be allowed to be called from non-sleepable context, I'd suggest
allocating id itself in the outer functions and later install the
pointer using idr_replace().

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/ipc/util.c b/ipc/util.c
index 74e1d9c7a98afcef566b80bf906e1398f94e7760..91ce0bc621b500614c398472441ee8e2c76625e6 100644 (file)
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -252,7 +252,7 @@ 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)
@@ -261,17 +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_above(&ids->ipcs_idr, new,
-                               (next_id < 0) ? 0 : ipcid_to_idx(next_id), &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++;
@@ -307,19 +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;
 }
 
@@ -375,9 +370,7 @@ 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);
+       int err = 0;
 
        /*
         * Take the lock as a writer since we are potentially going to add
@@ -413,9 +406,6 @@ retry:
        }
        up_write(&ids->rw_mutex);
 
-       if (err == -EAGAIN)
-               goto retry;
-
        return err;
 }