The patch titled
Subject: ipc: conserve sequence numbers in extended IPCMNI mode
has been removed from the -mm tree. Its filename was
ipc-conserve-sequence-numbers-in-extended-ipcmni-mode.patch
This patch was dropped because an alternative patch was merged
------------------------------------------------------
From: Waiman Long <longman@xxxxxxxxxx>
Subject: ipc: conserve sequence numbers in extended IPCMNI mode
The mixing in of a sequence number into the IPC IDs is probably to avoid
ID reuse in userspace as much as possible. With extended IPCMNI mode, the
number of usable sequence numbers is greatly reduced leading to higher
chance of ID reuse.
To address this issue, we need to conserve the sequence number space as
much as possible. Right now, the sequence number is incremented for every
new ID created. In reality, we only need to increment the sequence number
when one or more IDs have been removed previously to make sure that those
IDs will not be reused when a new one is built. This is being done only
in the new extended IPCMNI mode.
Link: http://lkml.kernel.org/r/1536352137-12003-5-git-send-email-longman@xxxxxxxxxx
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/ipc_namespace.h | 1 +
ipc/ipc_sysctl.c | 2 ++
ipc/util.c | 19 +++++++++++++++----
ipc/util.h | 2 ++
4 files changed, 20 insertions(+), 4 deletions(-)
--- a/include/linux/ipc_namespace.h~ipc-conserve-sequence-numbers-in-extended-ipcmni-mode
+++ a/include/linux/ipc_namespace.h
@@ -16,6 +16,7 @@ struct user_namespace;
struct ipc_ids {
int in_use;
unsigned short seq;
+ unsigned short deleted;
struct rw_semaphore rwsem;
struct idr ipcs_idr;
int max_idx;
--- a/ipc/ipc_sysctl.c~ipc-conserve-sequence-numbers-in-extended-ipcmni-mode
+++ a/ipc/ipc_sysctl.c
@@ -122,6 +122,7 @@ static int one = 1;
static int int_max = INT_MAX;
int ipc_mni = IPCMNI;
int ipc_mni_shift = IPCMNI_SHIFT;
+bool ipc_mni_extended;
static struct ctl_table ipc_kern_table[] = {
{
@@ -252,6 +253,7 @@ static int __init ipc_mni_extend(char *s
{
ipc_mni = IPCMNI_EXTEND;
ipc_mni_shift = IPCMNI_EXTEND_SHIFT;
+ ipc_mni_extended = true;
pr_info("IPCMNI extended to %d.\n", ipc_mni);
return 0;
}
--- a/ipc/util.c~ipc-conserve-sequence-numbers-in-extended-ipcmni-mode
+++ a/ipc/util.c
@@ -115,7 +115,8 @@ static const struct rhashtable_params ip
void ipc_init_ids(struct ipc_ids *ids)
{
ids->in_use = 0;
- ids->seq = 0;
+ ids->deleted = false;
+ ids->seq = ipc_mni_extended ? 0 : -1; /* seq # is pre-incremented */
init_rwsem(&ids->rwsem);
rhashtable_init(&ids->key_ht, &ipc_kht_params);
idr_init(&ids->ipcs_idr);
@@ -198,6 +199,11 @@ static inline int ipc_idr_alloc(struct i
{
int idx, next_id = -1;
+/*
+ * To conserve sequence number space with extended ipc_mni when new ID
+ * is built, the sequence number is incremented only when one or more
+ * IDs have been removed previously.
+ */
#ifdef CONFIG_CHECKPOINT_RESTORE
next_id = ids->next_id;
ids->next_id = -1;
@@ -216,9 +222,13 @@ static inline int ipc_idr_alloc(struct i
*/
if (next_id < 0) { /* !CHECKPOINT_RESTORE or next_id is unset */
- new->seq = ids->seq++;
- if (ids->seq > IPCID_SEQ_MAX)
- ids->seq = 0;
+ if (!ipc_mni_extended || ids->deleted) {
+ ids->seq++;
+ if (ids->seq > IPCID_SEQ_MAX)
+ ids->seq = 0;
+ ids->deleted = false;
+ }
+ new->seq = ids->seq;
idx = idr_alloc(&ids->ipcs_idr, new, 0, 0, GFP_NOWAIT);
} else {
new->seq = ipcid_to_seqx(next_id);
@@ -436,6 +446,7 @@ void ipc_rmid(struct ipc_ids *ids, struc
idr_remove(&ids->ipcs_idr, idx);
ipc_kht_remove(ids, ipcp);
ids->in_use--;
+ ids->deleted = true;
ipcp->deleted = true;
if (unlikely(idx == ids->max_idx)) {
--- a/ipc/util.h~ipc-conserve-sequence-numbers-in-extended-ipcmni-mode
+++ a/ipc/util.h
@@ -33,6 +33,7 @@
#ifdef CONFIG_SYSVIPC_SYSCTL
extern int ipc_mni;
extern int ipc_mni_shift;
+extern bool ipc_mni_extended;
#define IPCMNI_SEQ_SHIFT ipc_mni_shift
#define IPCMNI_IDX_MASK ((1 << ipc_mni_shift) - 1)
@@ -40,6 +41,7 @@ extern int ipc_mni_shift;
#else /* CONFIG_SYSVIPC_SYSCTL */
#define ipc_mni IPCMNI
+#define ipc_mni_extended false
#define IPCMNI_SEQ_SHIFT IPCMNI_SHIFT
#define IPCMNI_IDX_MASK ((1 << IPCMNI_SHIFT) - 1)
#endif /* CONFIG_SYSVIPC_SYSCTL */
_
Patches currently in -mm which might be from longman@xxxxxxxxxx are
debugobjects-move-printk-out-of-db-lock-critical-sections.patch
include-linux-nodemaskh-use-nr_node_ids-not-max_numnodes-in-__nodemask_pr_numnodes.patch
