diff options
| author | Stanislav Kinsbursky <skinsbursky@parallels.com> | 2013-01-04 15:34:50 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-01-04 16:11:45 -0800 |
| commit | 03f595668017f1a1fb971c02fc37140bc6e7bb1c (patch) | |
| tree | 3aa5c4b32b5fd396f0d74679548de8c09ca195a1 /ipc/util.c | |
| parent | 9afdacda0252fc1ddb7907728e878518edbcdfce (diff) | |
ipc: add sysctl to specify desired next object id
Add 3 new variables and sysctls to tune them (by one "next_id" variable
for messages, semaphores and shared memory respectively). This variable
can be used to set desired id for next allocated IPC object. By default
it's equal to -1 and old behaviour is preserved. If this variable is
non-negative, then desired idr will be extracted from it and used as a
start value to search for free IDR slot.
Notes:
1) this patch doesn't guarantee that the new object will have desired
id. So it's up to user space how to handle new object with wrong id.
2) After a sucessful id allocation attempt, "next_id" will be set back
to -1 (if it was non-negative).
[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/util.c')
| -rw-r--r-- | ipc/util.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/ipc/util.c b/ipc/util.c index 72fd0785ac9..74e1d9c7a98 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -122,6 +122,7 @@ void ipc_init_ids(struct ipc_ids *ids) ids->in_use = 0; ids->seq = 0; + ids->next_id = -1; { int seq_limit = INT_MAX/SEQ_MULTIPLIER; if (seq_limit > USHRT_MAX) @@ -252,6 +253,7 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size) kuid_t euid; kgid_t egid; int id, err; + int next_id = ids->next_id; if (size > IPCMNI) size = IPCMNI; @@ -264,7 +266,8 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size) rcu_read_lock(); spin_lock(&new->lock); - err = idr_get_new(&ids->ipcs_idr, new, &id); + err = idr_get_new_above(&ids->ipcs_idr, new, + (next_id < 0) ? 0 : ipcid_to_idx(next_id), &id); if (err) { spin_unlock(&new->lock); rcu_read_unlock(); @@ -277,9 +280,14 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size) new->cuid = new->uid = euid; new->gid = new->cgid = egid; - new->seq = ids->seq++; - if(ids->seq > ids->seq_max) - ids->seq = 0; + if (next_id < 0) { + new->seq = ids->seq++; + if (ids->seq > ids->seq_max) + ids->seq = 0; + } else { + new->seq = ipcid_to_seqx(next_id); + ids->next_id = -1; + } new->id = ipc_buildid(id, new->seq); return id; |