ipc: store ipcs into IDRs

This patch introduces ipcs storage into IDRs. The main changes are:
  . This ipc_ids structure is changed: the entries array is changed into a
    root idr structure.
  . The grow_ary() routine is removed: it is not needed anymore when adding
    an ipc structure, since we are now using the IDR facility.
  . The ipc_rmid() routine interface is changed:
       . there is no need for this routine to return the pointer passed in as
         argument: it is now declared as a void
       . since the id is now part of the kern_ipc_perm structure, no need to
         have it as an argument to the routine

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

1 files changed, 65 insertions, 46 deletions

diff --git a/ipc/sem.c b/ipc/sem.c
index 64ff4261f4e2..f92a2565d12b 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -90,7 +90,6 @@
 
 #define sem_lock(ns, id)        ((struct sem_array*)ipc_lock(&sem_ids(ns), id))
 #define sem_unlock(sma)         ipc_unlock(&(sma)->sem_perm)
-#define sem_rmid(ns, id)        ((struct sem_array*)ipc_rmid(&sem_ids(ns), id))
 #define sem_checkid(ns, sma, semid)     \
         ipc_checkid(&sem_ids(ns),&sma->sem_perm,semid)
 #define sem_buildid(ns, id, seq) \
@@ -99,7 +98,7 @@
 static struct ipc_ids init_sem_ids;
 
 static int newary(struct ipc_namespace *, key_t, int, int);
-static void freeary(struct ipc_namespace *ns, struct sem_array *sma, int id);
+static void freeary(struct ipc_namespace *, struct sem_array *);
 #ifdef CONFIG_PROC_FS
 static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
 #endif
@@ -129,7 +128,7 @@ static void __sem_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
         ns->sc_semopm = SEMOPM;
         ns->sc_semmni = SEMMNI;
         ns->used_sems = 0;
-        ipc_init_ids(ids, ns->sc_semmni);
+        ipc_init_ids(ids);
 }
 
 int sem_init_ns(struct ipc_namespace *ns)
@@ -146,20 +145,24 @@ int sem_init_ns(struct ipc_namespace *ns)
 
 void sem_exit_ns(struct ipc_namespace *ns)
 {
-        int i;
         struct sem_array *sma;
+        int next_id;
+        int total, in_use;
 
         mutex_lock(&sem_ids(ns).mutex);
-        for (i = 0; i <= sem_ids(ns).max_id; i++) {
-                sma = sem_lock(ns, i);
+
+        in_use = sem_ids(ns).in_use;
+
+        for (total = 0, next_id = 0; total < in_use; next_id++) {
+                sma = idr_find(&sem_ids(ns).ipcs_idr, next_id);
                 if (sma == NULL)
                         continue;
-
-                freeary(ns, sma, i);
+                ipc_lock_by_ptr(&sma->sem_perm);
+                freeary(ns, sma);
+                total++;
         }
         mutex_unlock(&sem_ids(ns).mutex);
 
-        ipc_fini_ids(ns->ids[IPC_SEM_IDS]);
         kfree(ns->ids[IPC_SEM_IDS]);
         ns->ids[IPC_SEM_IDS] = NULL;
 }
@@ -172,6 +175,11 @@ void __init sem_init (void)
                                 IPC_SEM_IDS, sysvipc_sem_proc_show);
 }
 
+static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
+{
+        ipc_rmid(&sem_ids(ns), &s->sem_perm);
+}
+
 /*
  * Lockless wakeup algorithm:
  * Without the check/retry algorithm a lockless wakeup is possible:
@@ -243,7 +251,7 @@ static int newary (struct ipc_namespace *ns, key_t key, int nsems, int semflg)
         }
         ns->used_sems += nsems;
 
-        sma->sem_id = sem_buildid(ns, id, sma->sem_perm.seq);
+        sma->sem_perm.id = sem_buildid(ns, id, sma->sem_perm.seq);
         sma->sem_base = (struct sem *) &sma[1];
         /* sma->sem_pending = NULL; */
         sma->sem_pending_last = &sma->sem_pending;
@@ -252,12 +260,12 @@ static int newary (struct ipc_namespace *ns, key_t key, int nsems, int semflg)
         sma->sem_ctime = get_seconds();
         sem_unlock(sma);
 
-        return sma->sem_id;
+        return sma->sem_perm.id;
 }
 
 asmlinkage long sys_semget (key_t key, int nsems, int semflg)
 {
-        int id, err = -EINVAL;
+        int err;
         struct sem_array *sma;
         struct ipc_namespace *ns;
 
@@ -265,34 +273,50 @@ asmlinkage long sys_semget (key_t key, int nsems, int semflg)
 
         if (nsems < 0 || nsems > ns->sc_semmsl)
                 return -EINVAL;
-        mutex_lock(&sem_ids(ns).mutex);
-        
+
+        err = idr_pre_get(&sem_ids(ns).ipcs_idr, GFP_KERNEL);
+
         if (key == IPC_PRIVATE) {
-                err = newary(ns, key, nsems, semflg);
-        } else if ((id = ipc_findkey(&sem_ids(ns), key)) == -1) {  /* key not used */
-                if (!(semflg & IPC_CREAT))
-                        err = -ENOENT;
-                else
+                if (!err)
+                        err = -ENOMEM;
+                else {
+                        mutex_lock(&sem_ids(ns).mutex);
                         err = newary(ns, key, nsems, semflg);
-        } else if (semflg & IPC_CREAT && semflg & IPC_EXCL) {
-                err = -EEXIST;
+                        mutex_unlock(&sem_ids(ns).mutex);
+                }
         } else {
-                sma = sem_lock(ns, id);
-                BUG_ON(sma==NULL);
-                if (nsems > sma->sem_nsems)
-                        err = -EINVAL;
-                else if (ipcperms(&sma->sem_perm, semflg))
-                        err = -EACCES;
-                else {
-                        int semid = sem_buildid(ns, id, sma->sem_perm.seq);
-                        err = security_sem_associate(sma, semflg);
-                        if (!err)
-                                err = semid;
+                mutex_lock(&sem_ids(ns).mutex);
+                sma = (struct sem_array *) ipc_findkey(&sem_ids(ns), key);
+                if (sma == NULL) {
+                        /* key not used */
+                        if (!(semflg & IPC_CREAT))
+                                err = -ENOENT;
+                        else if (!err)
+                                err = -ENOMEM;
+                        else
+                                err = newary(ns, key, nsems, semflg);
+                } else {
+                        /* sma has been locked by ipc_findkey() */
+
+                        if (semflg & IPC_CREAT && semflg & IPC_EXCL)
+                                err = -EEXIST;
+                        else {
+                                if (nsems > sma->sem_nsems)
+                                        err = -EINVAL;
+                                else if (ipcperms(&sma->sem_perm, semflg))
+                                        err = -EACCES;
+                                else {
+                                        err = security_sem_associate(sma,
+                                                                semflg);
+                                        if (!err)
+                                                err = sma->sem_perm.id;
+                                }
+                        }
+                        sem_unlock(sma);
                 }
-                sem_unlock(sma);
+                mutex_unlock(&sem_ids(ns).mutex);
         }
 
-        mutex_unlock(&sem_ids(ns).mutex);
         return err;
 }
 
@@ -491,11 +515,10 @@ static int count_semzcnt (struct sem_array * sma, ushort semnum)
  * the spinlock for this semaphore set hold. sem_ids.mutex remains locked
  * on exit.
  */
-static void freeary (struct ipc_namespace *ns, struct sem_array *sma, int id)
+static void freeary(struct ipc_namespace *ns, struct sem_array *sma)
 {
         struct sem_undo *un;
         struct sem_queue *q;
-        int size;
 
         /* Invalidate the existing undo structures for this semaphore set.
          * (They will be freed without any further action in exit_sem()
@@ -518,12 +541,11 @@ static void freeary (struct ipc_namespace *ns, struct sem_array *sma, int id)
                 q = n;
         }
 
-        /* Remove the semaphore set from the ID array*/
-        sma = sem_rmid(ns, id);
+        /* Remove the semaphore set from the IDR */
+        sem_rmid(ns, sma);
         sem_unlock(sma);
 
         ns->used_sems -= sma->sem_nsems;
-        size = sizeof (*sma) + sma->sem_nsems * sizeof (struct sem);
         security_sem_free(sma);
         ipc_rcu_putref(sma);
 }
@@ -584,7 +606,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid, int semnum,
                         seminfo.semusz = SEMUSZ;
                         seminfo.semaem = SEMAEM;
                 }
-                max_id = sem_ids(ns).max_id;
+                max_id = ipc_get_maxid(&sem_ids(ns));
                 mutex_unlock(&sem_ids(ns).mutex);
                 if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo))) 
                         return -EFAULT;
@@ -595,9 +617,6 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid, int semnum,
                 struct semid64_ds tbuf;
                 int id;
 
-                if(semid >= sem_ids(ns).entries->size)
-                        return -EINVAL;
-
                 memset(&tbuf,0,sizeof(tbuf));
 
                 sma = sem_lock(ns, semid);
@@ -612,7 +631,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid, int semnum,
                 if (err)
                         goto out_unlock;
 
-                id = sem_buildid(ns, semid, sma->sem_perm.seq);
+                id = sma->sem_perm.id;
 
                 kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
                 tbuf.sem_otime  = sma->sem_otime;
@@ -894,7 +913,7 @@ static int semctl_down(struct ipc_namespace *ns, int semid, int semnum,
 
         switch(cmd){
         case IPC_RMID:
-                freeary(ns, sma, semid);
+                freeary(ns, sma);
                 err = 0;
                 break;
         case IPC_SET:
@@ -1402,7 +1421,7 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
         return seq_printf(s,
                           "%10d %10d  %4o %10lu %5u %5u %5u %5u %10lu %10lu\n",
                           sma->sem_perm.key,
-                          sma->sem_id,
+                          sma->sem_perm.id,
                           sma->sem_perm.mode,
                           sma->sem_nsems,
                           sma->sem_perm.uid,