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, 69 insertions, 47 deletions

diff --git a/ipc/shm.c b/ipc/shm.c
index b9d272900a1e..dcc333239683 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -84,7 +84,7 @@ static void __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
         ns->shm_ctlall = SHMALL;
         ns->shm_ctlmni = SHMMNI;
         ns->shm_tot = 0;
-        ipc_init_ids(ids, 1);
+        ipc_init_ids(ids);
 }
 
 static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
@@ -112,20 +112,24 @@ int shm_init_ns(struct ipc_namespace *ns)
 
 void shm_exit_ns(struct ipc_namespace *ns)
 {
-        int i;
         struct shmid_kernel *shp;
+        int next_id;
+        int total, in_use;
 
         mutex_lock(&shm_ids(ns).mutex);
-        for (i = 0; i <= shm_ids(ns).max_id; i++) {
-                shp = shm_lock(ns, i);
+
+        in_use = shm_ids(ns).in_use;
+
+        for (total = 0, next_id = 0; total < in_use; next_id++) {
+                shp = idr_find(&shm_ids(ns).ipcs_idr, next_id);
                 if (shp == NULL)
                         continue;
-
+                ipc_lock_by_ptr(&shp->shm_perm);
                 do_shm_rmid(ns, shp);
+                total++;
         }
         mutex_unlock(&shm_ids(ns).mutex);
 
-        ipc_fini_ids(ns->ids[IPC_SHM_IDS]);
         kfree(ns->ids[IPC_SHM_IDS]);
         ns->ids[IPC_SHM_IDS] = NULL;
 }
@@ -146,9 +150,9 @@ static inline int shm_checkid(struct ipc_namespace *ns,
         return 0;
 }
 
-static inline struct shmid_kernel *shm_rmid(struct ipc_namespace *ns, int id)
+static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 {
-        return (struct shmid_kernel *)ipc_rmid(&shm_ids(ns), id);
+        ipc_rmid(&shm_ids(ns), &s->shm_perm);
 }
 
 static inline int shm_addid(struct ipc_namespace *ns, struct shmid_kernel *shp)
@@ -184,7 +188,7 @@ static void shm_open(struct vm_area_struct *vma)
 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 {
         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
-        shm_rmid(ns, shp->id);
+        shm_rmid(ns, shp);
         shm_unlock(shp);
         if (!is_file_hugepages(shp->shm_file))
                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
@@ -398,17 +402,18 @@ static int newseg (struct ipc_namespace *ns, key_t key, int shmflg, size_t size)
         shp->shm_ctim = get_seconds();
         shp->shm_segsz = size;
         shp->shm_nattch = 0;
-        shp->id = shm_buildid(ns, id, shp->shm_perm.seq);
+        shp->shm_perm.id = shm_buildid(ns, id, shp->shm_perm.seq);
         shp->shm_file = file;
         /*
          * shmid gets reported as "inode#" in /proc/pid/maps.
          * proc-ps tools use this. Changing this will break them.
          */
-        file->f_dentry->d_inode->i_ino = shp->id;
+        file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
 
         ns->shm_tot += numpages;
+        error = shp->shm_perm.id;
         shm_unlock(shp);
-        return shp->id;
+        return error;
 
 no_id:
         fput(file);
@@ -421,37 +426,52 @@ no_file:
 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
 {
         struct shmid_kernel *shp;
-        int err, id = 0;
+        int err;
         struct ipc_namespace *ns;
 
         ns = current->nsproxy->ipc_ns;
 
-        mutex_lock(&shm_ids(ns).mutex);
+        err = idr_pre_get(&shm_ids(ns).ipcs_idr, GFP_KERNEL);
+
         if (key == IPC_PRIVATE) {
-                err = newseg(ns, key, shmflg, size);
-        } else if ((id = ipc_findkey(&shm_ids(ns), key)) == -1) {
-                if (!(shmflg & IPC_CREAT))
-                        err = -ENOENT;
-                else
+                if (!err)
+                        err = -ENOMEM;
+                else {
+                        mutex_lock(&shm_ids(ns).mutex);
                         err = newseg(ns, key, shmflg, size);
-        } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
-                err = -EEXIST;
+                        mutex_unlock(&shm_ids(ns).mutex);
+                }
         } else {
-                shp = shm_lock(ns, id);
-                BUG_ON(shp==NULL);
-                if (shp->shm_segsz < size)
-                        err = -EINVAL;
-                else if (ipcperms(&shp->shm_perm, shmflg))
-                        err = -EACCES;
-                else {
-                        int shmid = shm_buildid(ns, id, shp->shm_perm.seq);
-                        err = security_shm_associate(shp, shmflg);
-                        if (!err)
-                                err = shmid;
+                mutex_lock(&shm_ids(ns).mutex);
+                shp = (struct shmid_kernel *) ipc_findkey(&shm_ids(ns), key);
+                if (shp == NULL) {
+                        if (!(shmflg & IPC_CREAT))
+                                err = -ENOENT;
+                        else if (!err)
+                                err = -ENOMEM;
+                        else
+                                err = newseg(ns, key, shmflg, size);
+                } else {
+                        /* shp has been locked by ipc_findkey() */
+
+                        if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL))
+                                err = -EEXIST;
+                        else {
+                                if (shp->shm_segsz < size)
+                                        err = -EINVAL;
+                                else if (ipcperms(&shp->shm_perm, shmflg))
+                                        err = -EACCES;
+                                else {
+                                        err = security_shm_associate(shp,
+                                                                shmflg);
+                                        if (!err)
+                                                err = shp->shm_perm.id;
+                                }
+                        }
+                        shm_unlock(shp);
                 }
-                shm_unlock(shp);
+                mutex_unlock(&shm_ids(ns).mutex);
         }
-        mutex_unlock(&shm_ids(ns).mutex);
 
         return err;
 }
@@ -550,17 +570,20 @@ static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminf
 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
                 unsigned long *swp)
 {
-        int i;
+        int next_id;
+        int total, in_use;
 
         *rss = 0;
         *swp = 0;
 
-        for (i = 0; i <= shm_ids(ns).max_id; i++) {
+        in_use = shm_ids(ns).in_use;
+
+        for (total = 0, next_id = 0; total < in_use; next_id++) {
                 struct shmid_kernel *shp;
                 struct inode *inode;
 
-                shp = shm_get(ns, i);
-                if(!shp)
+                shp = shm_get(ns, next_id);
+                if (shp == NULL)
                         continue;
 
                 inode = shp->shm_file->f_path.dentry->d_inode;
@@ -575,6 +598,8 @@ static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
                         *swp += info->swapped;
                         spin_unlock(&info->lock);
                 }
+
+                total++;
         }
 }
 
@@ -611,7 +636,7 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
                 if(copy_shminfo_to_user (buf, &shminfo, version))
                         return -EFAULT;
                 /* reading a integer is always atomic */
-                err= shm_ids(ns).max_id;
+                err = ipc_get_maxid(&shm_ids(ns));
                 if(err<0)
                         err = 0;
                 goto out;
@@ -631,7 +656,7 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
                 shm_info.shm_tot = ns->shm_tot;
                 shm_info.swap_attempts = 0;
                 shm_info.swap_successes = 0;
-                err = shm_ids(ns).max_id;
+                err = ipc_get_maxid(&shm_ids(ns));
                 mutex_unlock(&shm_ids(ns).mutex);
                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
                         err = -EFAULT;
@@ -651,11 +676,8 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
                 if(shp==NULL) {
                         err = -EINVAL;
                         goto out;
-                } else if(cmd==SHM_STAT) {
-                        err = -EINVAL;
-                        if (shmid > shm_ids(ns).max_id)
-                                goto out_unlock;
-                        result = shm_buildid(ns, shmid, shp->shm_perm.seq);
+                } else if (cmd == SHM_STAT) {
+                        result = shp->shm_perm.id;
                 } else {
                         err = shm_checkid(ns, shp,shmid);
                         if(err)
@@ -925,7 +947,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
 
         file->private_data = sfd;
         file->f_mapping = shp->shm_file->f_mapping;
-        sfd->id = shp->id;
+        sfd->id = shp->shm_perm.id;
         sfd->ns = get_ipc_ns(ns);
         sfd->file = shp->shm_file;
         sfd->vm_ops = NULL;
@@ -1094,7 +1116,7 @@ static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
                 format = BIG_STRING;
         return seq_printf(s, format,
                           shp->shm_perm.key,
-                          shp->id,
+                          shp->shm_perm.id,
                           shp->shm_perm.mode,
                           shp->shm_segsz,
                           shp->shm_cprid,