[PATCH 03/04]
This patch makes use of the target id specified by a previous write into
/proc/self/next_id as the id to use to allocate the next IPC object.
Signed-off-by: Nadia Derbey <[EMAIL PROTECTED]>
---
include/linux/sysids.h | 7 +++++++
ipc/util.c | 40 ++++++++++++++++++++++++++++++++--------
kernel/nextid.c | 2 +-
3 files changed, 40 insertions(+), 9 deletions(-)
Index: linux-2.6.25-rc8-mm1/include/linux/sysids.h
===================================================================
--- linux-2.6.25-rc8-mm1.orig/include/linux/sysids.h 2008-04-04
14:18:04.000000000 +0200
+++ linux-2.6.25-rc8-mm1/include/linux/sysids.h 2008-04-04 14:37:45.000000000
+0200
@@ -37,9 +37,16 @@ struct sys_id {
long *blocks[0];
};
+#define next_ipcid(tsk) ((tsk)->next_id
\
+ ? ((tsk)->next_id->nids \
+ ? ID_AT((tsk)->next_id, 0) \
+ : -1) \
+ : -1)
+
extern ssize_t get_nextid(struct task_struct *, char *, size_t);
extern int set_nextid(struct task_struct *, char *);
extern int reset_nextid(struct task_struct *);
+extern void id_blocks_free(struct sys_id *);
static inline void exit_nextid(struct task_struct *tsk)
{
Index: linux-2.6.25-rc8-mm1/kernel/nextid.c
===================================================================
--- linux-2.6.25-rc8-mm1.orig/kernel/nextid.c 2008-04-04 14:28:13.000000000
+0200
+++ linux-2.6.25-rc8-mm1/kernel/nextid.c 2008-04-04 14:38:38.000000000
+0200
@@ -49,7 +49,7 @@ out_undo_partial_alloc:
return NULL;
}
-static void id_blocks_free(struct sys_id *ids)
+void id_blocks_free(struct sys_id *ids)
{
if (ids == NULL)
return;
Index: linux-2.6.25-rc8-mm1/ipc/util.c
===================================================================
--- linux-2.6.25-rc8-mm1.orig/ipc/util.c 2008-04-04 13:11:37.000000000
+0200
+++ linux-2.6.25-rc8-mm1/ipc/util.c 2008-04-04 14:41:53.000000000 +0200
@@ -260,6 +260,7 @@ int ipc_get_maxid(struct ipc_ids *ids)
int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
{
int id, err;
+ int next_id;
if (size > IPCMNI)
size = IPCMNI;
@@ -267,20 +268,43 @@ int ipc_addid(struct ipc_ids* ids, struc
if (ids->in_use >= size)
return -ENOSPC;
- err = idr_get_new(&ids->ipcs_idr, new, &id);
- if (err)
- return err;
+ next_id = next_ipcid(current);
+ if (next_id >= 0) {
+ /* There is a target id specified, try to use it */
+ int new_lid = next_id % SEQ_MULTIPLIER;
+
+ if (next_id !=
+ (new_lid + (next_id / SEQ_MULTIPLIER) * SEQ_MULTIPLIER))
+ return -EINVAL;
+
+ err = idr_get_new_above(&ids->ipcs_idr, new, new_lid, &id);
+ if (err)
+ return err;
+ if (id != new_lid) {
+ idr_remove(&ids->ipcs_idr, id);
+ return -EBUSY;
+ }
+
+ new->id = next_id;
+ new->seq = next_id / SEQ_MULTIPLIER;
+ id_blocks_free(current->next_id);
+ current->next_id = NULL;
+ } else {
+ err = idr_get_new(&ids->ipcs_idr, new, &id);
+ if (err)
+ return err;
+
+ new->seq = ids->seq++;
+ if (ids->seq > ids->seq_max)
+ ids->seq = 0;
+ new->id = ipc_buildid(id, new->seq);
+ }
ids->in_use++;
new->cuid = new->uid = current->euid;
new->gid = new->cgid = current->egid;
- new->seq = ids->seq++;
- if(ids->seq > ids->seq_max)
- ids->seq = 0;
-
- new->id = ipc_buildid(id, new->seq);
spin_lock_init(&new->lock);
new->deleted = 0;
rcu_read_lock();
--
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