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>
diff --git a/ipc/util.c b/ipc/util.c
index 44e5135..2a20587 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -129,23 +129,16 @@
/**
* ipc_init_ids - initialise IPC identifiers
* @ids: Identifier set
- * @size: Number of identifiers
*
- * Given a size for the ipc identifier range (limited below IPCMNI)
- * set up the sequence range to use then allocate and initialise the
- * array itself.
+ * Set up the sequence range to use for the ipc identifier range (limited
+ * below IPCMNI) then initialise the ids idr.
*/
-void ipc_init_ids(struct ipc_ids* ids, int size)
+void ipc_init_ids(struct ipc_ids *ids)
{
- int i;
-
mutex_init(&ids->mutex);
- if(size > IPCMNI)
- size = IPCMNI;
ids->in_use = 0;
- ids->max_id = -1;
ids->seq = 0;
{
int seq_limit = INT_MAX/SEQ_MULTIPLIER;
@@ -155,17 +148,7 @@
ids->seq_max = seq_limit;
}
- ids->entries = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*size +
- sizeof(struct ipc_id_ary));
-
- if(ids->entries == NULL) {
- printk(KERN_ERR "ipc_init_ids() failed, ipc service disabled.\n");
- size = 0;
- ids->entries = &ids->nullentry;
- }
- ids->entries->size = size;
- for(i=0;i<size;i++)
- ids->entries->p[i] = NULL;
+ idr_init(&ids->ipcs_idr);
}
#ifdef CONFIG_PROC_FS
@@ -209,72 +192,73 @@
* @key: The key to find
*
* Requires ipc_ids.mutex locked.
- * Returns the identifier if found or -1 if not.
+ * Returns the LOCKED pointer to the ipc structure if found or NULL
+ * if not.
+ * If key is found ipc contains its ipc structure
*/
-int ipc_findkey(struct ipc_ids* ids, key_t key)
+struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
{
- int id;
- struct kern_ipc_perm* p;
- int max_id = ids->max_id;
+ struct kern_ipc_perm *ipc;
+ int next_id;
+ int total;
- /*
- * rcu_dereference() is not needed here
- * since ipc_ids.mutex is held
- */
- for (id = 0; id <= max_id; id++) {
- p = ids->entries->p[id];
- if(p==NULL)
+ for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
+ ipc = idr_find(&ids->ipcs_idr, next_id);
+
+ if (ipc == NULL)
continue;
- if (key == p->key)
- return id;
+
+ if (ipc->key != key) {
+ total++;
+ continue;
+ }
+
+ ipc_lock_by_ptr(ipc);
+ return ipc;
}
- return -1;
+
+ return NULL;
}
-/*
- * Requires ipc_ids.mutex locked
+/**
+ * ipc_get_maxid - get the last assigned id
+ * @ids: IPC identifier set
+ *
+ * Called with ipc_ids.mutex held.
*/
-static int grow_ary(struct ipc_ids* ids, int newsize)
+
+int ipc_get_maxid(struct ipc_ids *ids)
{
- struct ipc_id_ary* new;
- struct ipc_id_ary* old;
- int i;
- int size = ids->entries->size;
+ struct kern_ipc_perm *ipc;
+ int max_id = -1;
+ int total, id;
- if(newsize > IPCMNI)
- newsize = IPCMNI;
- if(newsize <= size)
- return newsize;
+ if (ids->in_use == 0)
+ return -1;
- new = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*newsize +
- sizeof(struct ipc_id_ary));
- if(new == NULL)
- return size;
- new->size = newsize;
- memcpy(new->p, ids->entries->p, sizeof(struct kern_ipc_perm *)*size);
- for(i=size;i<newsize;i++) {
- new->p[i] = NULL;
+ if (ids->in_use == IPCMNI)
+ return IPCMNI - 1;
+
+ /* Look for the last assigned id */
+ total = 0;
+ for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
+ ipc = idr_find(&ids->ipcs_idr, id);
+ if (ipc != NULL) {
+ max_id = id;
+ total++;
+ }
}
- old = ids->entries;
-
- /*
- * Use rcu_assign_pointer() to make sure the memcpyed contents
- * of the new array are visible before the new array becomes visible.
- */
- rcu_assign_pointer(ids->entries, new);
-
- __ipc_fini_ids(ids, old);
- return newsize;
+ return max_id;
}
/**
* ipc_addid - add an IPC identifier
* @ids: IPC identifier set
* @new: new IPC permission set
- * @size: new size limit for the id array
+ * @size: limit for the number of used ids
*
- * Add an entry 'new' to the IPC arrays. The permissions object is
+ * Add an entry 'new' to the IPC idr. The permissions object is
* initialised and the first free entry is set up and the id assigned
* is returned. The list is returned in a locked state on success.
* On failure the list is not locked and -1 is returned.
@@ -284,23 +268,23 @@
int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
{
- int id;
-
- size = grow_ary(ids,size);
+ int id, err;
/*
* rcu_dereference()() is not needed here since
* ipc_ids.mutex is held
*/
- for (id = 0; id < size; id++) {
- if(ids->entries->p[id] == NULL)
- goto found;
- }
- return -1;
-found:
+ if (size > IPCMNI)
+ size = IPCMNI;
+
+ if (ids->in_use >= size)
+ return -1;
+
+ err = idr_get_new(&ids->ipcs_idr, new, &id);
+ if (err)
+ return -1;
+
ids->in_use++;
- if (id > ids->max_id)
- ids->max_id = id;
new->cuid = new->uid = current->euid;
new->gid = new->cgid = current->egid;
@@ -313,48 +297,32 @@
new->deleted = 0;
rcu_read_lock();
spin_lock(&new->lock);
- ids->entries->p[id] = new;
return id;
}
/**
* ipc_rmid - remove an IPC identifier
* @ids: identifier set
- * @id: Identifier to remove
+ * @id: ipc perm structure containing the identifier to remove
*
* The identifier must be valid, and in use. The kernel will panic if
* fed an invalid identifier. The entry is removed and internal
- * variables recomputed. The object associated with the identifier
- * is returned.
- * ipc_ids.mutex and the spinlock for this ID is hold before this function
- * is called, and remain locked on the exit.
+ * variables recomputed.
+ * ipc_ids.mutex and the spinlock for this ID are held before this
+ * function is called, and remain locked on the exit.
*/
-struct kern_ipc_perm* ipc_rmid(struct ipc_ids* ids, int id)
+void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
{
- struct kern_ipc_perm* p;
- int lid = id % SEQ_MULTIPLIER;
- BUG_ON(lid >= ids->entries->size);
+ int lid = ipcp->id % SEQ_MULTIPLIER;
- /*
- * do not need a rcu_dereference()() here to force ordering
- * on Alpha, since the ipc_ids.mutex is held.
- */
- p = ids->entries->p[lid];
- ids->entries->p[lid] = NULL;
- BUG_ON(p==NULL);
+ idr_remove(&ids->ipcs_idr, lid);
+
ids->in_use--;
- if (lid == ids->max_id) {
- do {
- lid--;
- if(lid == -1)
- break;
- } while (ids->entries->p[lid] == NULL);
- ids->max_id = lid;
- }
- p->deleted = 1;
- return p;
+ ipcp->deleted = 1;
+
+ return;
}
/**
@@ -613,33 +581,26 @@
* if in the future ipc_get() is used by other places without ipc_ids.mutex
* down, then ipc_get() needs read memery barriers as ipc_lock() does.
*/
-struct kern_ipc_perm* ipc_get(struct ipc_ids* ids, int id)
+struct kern_ipc_perm *ipc_get(struct ipc_ids *ids, int id)
{
- struct kern_ipc_perm* out;
+ struct kern_ipc_perm *out;
int lid = id % SEQ_MULTIPLIER;
- if(lid >= ids->entries->size)
- return NULL;
- out = ids->entries->p[lid];
+ out = idr_find(&ids->ipcs_idr, lid);
return out;
}
-struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id)
+struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
{
- struct kern_ipc_perm* out;
+ struct kern_ipc_perm *out;
int lid = id % SEQ_MULTIPLIER;
- struct ipc_id_ary* entries;
rcu_read_lock();
- entries = rcu_dereference(ids->entries);
- if(lid >= entries->size) {
+ out = idr_find(&ids->ipcs_idr, lid);
+ if (out == NULL) {
rcu_read_unlock();
return NULL;
}
- out = entries->p[lid];
- if(out == NULL) {
- rcu_read_unlock();
- return NULL;
- }
+
spin_lock(&out->lock);
/* ipc_rmid() may have already freed the ID while ipc_lock
@@ -650,6 +611,7 @@
rcu_read_unlock();
return NULL;
}
+
return out;
}
@@ -707,27 +669,30 @@
struct ipc_proc_iface *iface;
};
-static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
+/*
+ * This routine locks the ipc structure found at least at position pos.
+ */
+struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
+ loff_t *new_pos)
{
- struct ipc_proc_iter *iter = s->private;
- struct ipc_proc_iface *iface = iter->iface;
- struct kern_ipc_perm *ipc = it;
- loff_t p;
- struct ipc_ids *ids;
+ struct kern_ipc_perm *ipc;
+ int total, id;
- ids = iter->ns->ids[iface->ids];
+ total = 0;
+ for (id = 0; id < pos && total < ids->in_use; id++) {
+ ipc = idr_find(&ids->ipcs_idr, id);
+ if (ipc != NULL)
+ total++;
+ }
- /* If we had an ipc id locked before, unlock it */
- if (ipc && ipc != SEQ_START_TOKEN)
- ipc_unlock(ipc);
+ if (total >= ids->in_use)
+ return NULL;
- /*
- * p = *pos - 1 (because id 0 starts at position 1)
- * + 1 (because we increment the position by one)
- */
- for (p = *pos; p <= ids->max_id; p++) {
- if ((ipc = ipc_lock(ids, p)) != NULL) {
- *pos = p + 1;
+ for ( ; pos < IPCMNI; pos++) {
+ ipc = idr_find(&ids->ipcs_idr, pos);
+ if (ipc != NULL) {
+ *new_pos = pos + 1;
+ ipc_lock_by_ptr(ipc);
return ipc;
}
}
@@ -736,6 +701,19 @@
return NULL;
}
+static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
+{
+ struct ipc_proc_iter *iter = s->private;
+ struct ipc_proc_iface *iface = iter->iface;
+ struct kern_ipc_perm *ipc = it;
+
+ /* If we had an ipc id locked before, unlock it */
+ if (ipc && ipc != SEQ_START_TOKEN)
+ ipc_unlock(ipc);
+
+ return sysvipc_find_ipc(iter->ns->ids[iface->ids], *pos, pos);
+}
+
/*
* File positions: pos 0 -> header, pos n -> ipc id + 1.
* SeqFile iterator: iterator value locked shp or SEQ_TOKEN_START.
@@ -744,8 +722,6 @@
{
struct ipc_proc_iter *iter = s->private;
struct ipc_proc_iface *iface = iter->iface;
- struct kern_ipc_perm *ipc;
- loff_t p;
struct ipc_ids *ids;
ids = iter->ns->ids[iface->ids];
@@ -765,13 +741,7 @@
return SEQ_START_TOKEN;
/* Find the (pos-1)th ipc */
- for (p = *pos - 1; p <= ids->max_id; p++) {
- if ((ipc = ipc_lock(ids, p)) != NULL) {
- *pos = p + 1;
- return ipc;
- }
- }
- return NULL;
+ return sysvipc_find_ipc(ids, *pos - 1, pos);
}
static void sysvipc_proc_stop(struct seq_file *s, void *it)