IPC: fix error case when idr-cache is empty in ipcget()

With the use of idr to store the ipc, the case where the idr cache is
empty, when idr_get_new is called (this may happen even if we call
idr_pre_get() before), is not well handled: it lets
semget()/shmget()/msgget() return ENOSPC when this cache is empty, what 1.
does not reflect the facts and 2.  does not conform to the man(s).

This patch fixes this by retrying the whole process of allocation in this case.

Signed-off-by: Pierre Peiffer <pierre.peiffer@bull.net>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/ipc/msg.c b/ipc/msg.c
index ccf5f495db7b851cb4ae92d40acad93919b25a49..fdf3db5731ce8df2cfd038f40c69710243d85338 100644 (file)
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -203,10 +203,10 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
         * ipc_addid() locks msq
         */
        id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
-       if (id == -1) {
+       if (id < 0) {
                security_msg_queue_free(msq);
                ipc_rcu_putref(msq);
-               return -ENOSPC;
+               return id;
        }
 
        msq->q_perm.id = msg_buildid(id, msq->q_perm.seq);

diff --git a/ipc/sem.c b/ipc/sem.c
index 7617f4f34edc4f914541c4b3d6fa2ce5f2c66e7e..35952c0bae4629cac017c4c62623c91a022ebee5 100644 (file)
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -283,10 +283,10 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
        }
 
        id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
-       if(id == -1) {
+       if (id < 0) {
                security_sem_free(sma);
                ipc_rcu_putref(sma);
-               return -ENOSPC;
+               return id;
        }
        ns->used_sems += nsems;
 

diff --git a/ipc/shm.c b/ipc/shm.c
index 05c97c7513c2671b06523dd986b2cc4774dd8345..3818fae625c5252363380fa9c7a521e8b5c1a7d1 100644 (file)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -433,10 +433,11 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
        if (IS_ERR(file))
                goto no_file;
 
-       error = -ENOSPC;
        id = shm_addid(ns, shp);
-       if(id == -1) 
+       if (id < 0) {
+               error = id;
                goto no_id;
+       }
 
        shp->shm_cprid = task_tgid_vnr(current);
        shp->shm_lprid = 0;

diff --git a/ipc/util.c b/ipc/util.c
index b42fbd58973a02f2d59a29204a23c5323bcd960c..1aa0ebf71bac7e5c30559eb0f60a89bdc6688efb 100644 (file)
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -262,7 +262,7 @@ int ipc_get_maxid(struct ipc_ids *ids)
  *     Add an entry 'new' to the IPC ids idr. The permissions object is
  *     initialised and the first free entry is set up and the id assigned
  *     is returned. The 'new' entry is returned in a locked state on success.
- *     On failure the entry is not locked and -1 is returned.
+ *     On failure the entry is not locked and a negative err-code is returned.
  *
  *     Called with ipc_ids.rw_mutex held as a writer.
  */
@@ -275,11 +275,11 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
                size = IPCMNI;
 
        if (ids->in_use >= size)
-               return -1;
+               return -ENOSPC;
 
        err = idr_get_new(&ids->ipcs_idr, new, &id);
        if (err)
-               return -1;
+               return err;
 
        ids->in_use++;
 
@@ -311,7 +311,7 @@ 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)
@@ -321,6 +321,9 @@ int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
        err = ops->getnew(ns, params);
        up_write(&ids->rw_mutex);
 
+       if (err == -EAGAIN)
+               goto retry;
+
        return err;
 }
 
@@ -374,7 +377,7 @@ 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);
 
        /*
@@ -411,6 +414,9 @@ int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
        }
        up_write(&ids->rw_mutex);
 
+       if (err == -EAGAIN)
+               goto retry;
+
        return err;
 }