The patch titled
Subject: ipc: add sysctl to specify desired next object id
has been added to the -mm tree. Its filename is
ipc-add-sysctl-to-specify-desired-next-object-id.patch
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From: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
Subject: 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).
Signed-off-by: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
Cc: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/ipc_namespace.h | 1 +
ipc/ipc_sysctl.c | 28 ++++++++++++++++++++++++++++
ipc/util.c | 16 ++++++++++++----
ipc/util.h | 1 +
4 files changed, 42 insertions(+), 4 deletions(-)
diff -puN include/linux/ipc_namespace.h~ipc-add-sysctl-to-specify-desired-next-object-id include/linux/ipc_namespace.h
--- a/include/linux/ipc_namespace.h~ipc-add-sysctl-to-specify-desired-next-object-id
+++ a/include/linux/ipc_namespace.h
@@ -24,6 +24,7 @@ struct ipc_ids {
unsigned short seq_max;
struct rw_semaphore rw_mutex;
struct idr ipcs_idr;
+ int next_id;
};
struct ipc_namespace {
diff -puN ipc/ipc_sysctl.c~ipc-add-sysctl-to-specify-desired-next-object-id ipc/ipc_sysctl.c
--- a/ipc/ipc_sysctl.c~ipc-add-sysctl-to-specify-desired-next-object-id
+++ a/ipc/ipc_sysctl.c
@@ -158,6 +158,7 @@ static int proc_ipcauto_dointvec_minmax(
static int zero;
static int one = 1;
+static int int_max = INT_MAX;
static struct ctl_table ipc_kern_table[] = {
{
@@ -227,6 +228,33 @@ static struct ctl_table ipc_kern_table[]
.extra1 = &zero,
.extra2 = &one,
},
+ {
+ .procname = "sem_next_id",
+ .data = &init_ipc_ns.ids[IPC_SEM_IDS].next_id,
+ .maxlen = sizeof(init_ipc_ns.ids[IPC_SEM_IDS].next_id),
+ .mode = 0644,
+ .proc_handler = proc_ipc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &int_max,
+ },
+ {
+ .procname = "msg_next_id",
+ .data = &init_ipc_ns.ids[IPC_MSG_IDS].next_id,
+ .maxlen = sizeof(init_ipc_ns.ids[IPC_MSG_IDS].next_id),
+ .mode = 0644,
+ .proc_handler = proc_ipc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &int_max,
+ },
+ {
+ .procname = "shm_next_id",
+ .data = &init_ipc_ns.ids[IPC_SHM_IDS].next_id,
+ .maxlen = sizeof(init_ipc_ns.ids[IPC_SHM_IDS].next_id),
+ .mode = 0644,
+ .proc_handler = proc_ipc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &int_max,
+ },
{}
};
diff -puN ipc/util.c~ipc-add-sysctl-to-specify-desired-next-object-id ipc/util.c
--- a/ipc/util.c~ipc-add-sysctl-to-specify-desired-next-object-id
+++ a/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, struc
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, struc
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, struc
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;
diff -puN ipc/util.h~ipc-add-sysctl-to-specify-desired-next-object-id ipc/util.h
--- a/ipc/util.h~ipc-add-sysctl-to-specify-desired-next-object-id
+++ a/ipc/util.h
@@ -92,6 +92,7 @@ void __init ipc_init_proc_interface(cons
#define IPC_SHM_IDS 2
#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
+#define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
/* must be called with ids->rw_mutex acquired for writing */
int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
_
Patches currently in -mm which might be from skinsbursky@xxxxxxxxxxxxx are
origin.patch
proc-check-vma-vm_file-before-dereferencing.patch
ipc-remove-forced-assignment-of-selected-message.patch
ipc-add-sysctl-to-specify-desired-next-object-id.patch
ipc-add-sysctl-to-specify-desired-next-object-id-checkpatch-fixes.patch
ipc-message-queue-receive-cleanup.patch
ipc-message-queue-copy-feature-introduced.patch
selftests-ipc-message-queue-copy-feature-test.patch
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