The patch titled
Subject: ipc: allow boot time extension of IPCMNI from 32k to 8M
has been removed from the -mm tree. Its filename was
ipc-allow-boot-time-extension-of-ipcmni-from-32k-to-8m.patch
This patch was dropped because an alternative patch was merged
------------------------------------------------------
From: Waiman Long <longman@xxxxxxxxxx>
Subject: ipc: allow boot time extension of IPCMNI from 32k to 8M
The maximum number of unique System V IPC identifiers was limited to 32k.
That limit should be big enough for most use cases.
However, there are some users out there requesting for more, especially
those that are migrating from Solaris which uses 24 bits for unique
identifiers. To satisfy the need of those users, a new boot time kernel
option "ipcmni_extend" is added to extend the IPCMNI value to 8M. This is
a 256X increase which hopefully is big enough for them.
The use of this new option will change the pattern of the IPC identifiers
returned by functions like shmget(2). An application that depends on such
pattern may not work properly. So it should only be used if the users
really need more than 32k of unique IPC numbers.
This new option does have the side effect of reducing the maximum number
of unique sequence numbers from 64k down to 256. So it is a trade-off.
The computation of a new IPC id is not done in the performance critical
path. So a little bit of additional overhead shouldn't have any real
performance impact.
[akpm@xxxxxxxxxxxxxxxxxxxx: coding-style fixes]
Link: http://lkml.kernel.org/r/1536352137-12003-4-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>
---
Documentation/admin-guide/kernel-parameters.txt | 3
ipc/ipc_sysctl.c | 12 +++
ipc/util.c | 10 +--
ipc/util.h | 44 +++++++++++---
4 files changed, 54 insertions(+), 15 deletions(-)
--- a/Documentation/admin-guide/kernel-parameters.txt~ipc-allow-boot-time-extension-of-ipcmni-from-32k-to-8m
+++ a/Documentation/admin-guide/kernel-parameters.txt
@@ -1812,6 +1812,9 @@
ip= [IP_PNP]
See Documentation/filesystems/nfs/nfsroot.txt.
+ ipcmni_extend [KNL] Extend the maximum number of unique System V
+ IPC identifiers from 32,768 to 8,388,608.
+
irqaffinity= [SMP] Set the default irq affinity mask
The argument is a cpu list, as described above.
--- a/ipc/ipc_sysctl.c~ipc-allow-boot-time-extension-of-ipcmni-from-32k-to-8m
+++ a/ipc/ipc_sysctl.c
@@ -120,7 +120,8 @@ static int proc_ipc_sem_dointvec(struct
static int zero;
static int one = 1;
static int int_max = INT_MAX;
-static int ipc_mni = IPCMNI;
+int ipc_mni = IPCMNI;
+int ipc_mni_shift = IPCMNI_SHIFT;
static struct ctl_table ipc_kern_table[] = {
{
@@ -246,3 +247,12 @@ static int __init ipc_sysctl_init(void)
}
device_initcall(ipc_sysctl_init);
+
+static int __init ipc_mni_extend(char *str)
+{
+ ipc_mni = IPCMNI_EXTEND;
+ ipc_mni_shift = IPCMNI_EXTEND_SHIFT;
+ pr_info("IPCMNI extended to %d.\n", ipc_mni);
+ return 0;
+}
+early_param("ipcmni_extend", ipc_mni_extend);
--- a/ipc/util.c~ipc-allow-boot-time-extension-of-ipcmni-from-32k-to-8m
+++ a/ipc/util.c
@@ -110,7 +110,7 @@ static const struct rhashtable_params ip
* @ids: ipc identifier set
*
* Set up the sequence range to use for the ipc identifier range (limited
- * below IPCMNI) then initialise the keys hashtable and ids idr.
+ * below ipc_mni) then initialise the keys hashtable and ids idr.
*/
void ipc_init_ids(struct ipc_ids *ids)
{
@@ -226,7 +226,7 @@ static inline int ipc_idr_alloc(struct i
0, GFP_NOWAIT);
}
if (idx >= 0)
- new->id = SEQ_MULTIPLIER * new->seq + idx;
+ new->id = (new->seq << IPCMNI_SEQ_SHIFT) + idx;
return idx;
}
@@ -254,8 +254,8 @@ int ipc_addid(struct ipc_ids *ids, struc
/* 1) Initialize the refcount so that ipc_rcu_putref works */
refcount_set(&new->refcount, 1);
- if (limit > IPCMNI)
- limit = IPCMNI;
+ if (limit > ipc_mni)
+ limit = ipc_mni;
if (ids->in_use >= limit)
return -ENOSPC;
@@ -738,7 +738,7 @@ static struct kern_ipc_perm *sysvipc_fin
if (total >= ids->in_use)
return NULL;
- for (; pos < IPCMNI; pos++) {
+ for (; pos < ipc_mni; pos++) {
ipc = idr_find(&ids->ipcs_idr, pos);
if (ipc != NULL) {
*new_pos = pos + 1;
--- a/ipc/util.h~ipc-allow-boot-time-extension-of-ipcmni-from-32k-to-8m
+++ a/ipc/util.h
@@ -15,8 +15,34 @@
#include <linux/err.h>
#include <linux/ipc_namespace.h>
-#define IPCMNI 32768 /* <= MAX_INT limit for ipc arrays (including sysctl changes) */
-#define SEQ_MULTIPLIER (IPCMNI)
+/*
+ * The IPC ID contains 2 separate numbers - index and sequence number.
+ * By default,
+ * bits 0-14: index (32k, 15 bits)
+ * bits 15-30: sequence number (64k, 16 bits)
+ *
+ * When IPCMNI extension mode is turned on, the composition changes:
+ * bits 0-22: index (8M, 23 bits)
+ * bits 23-30: sequence number (256, 8 bits)
+ */
+#define IPCMNI_SHIFT 15
+#define IPCMNI_EXTEND_SHIFT 23
+#define IPCMNI (1 << IPCMNI_SHIFT)
+#define IPCMNI_EXTEND (1 << IPCMNI_EXTEND_SHIFT)
+
+#ifdef CONFIG_SYSVIPC_SYSCTL
+extern int ipc_mni;
+extern int ipc_mni_shift;
+
+#define IPCMNI_SEQ_SHIFT ipc_mni_shift
+#define IPCMNI_IDX_MASK ((1 << ipc_mni_shift) - 1)
+
+#else /* CONFIG_SYSVIPC_SYSCTL */
+
+#define ipc_mni IPCMNI
+#define IPCMNI_SEQ_SHIFT IPCMNI_SHIFT
+#define IPCMNI_IDX_MASK ((1 << IPCMNI_SHIFT) - 1)
+#endif /* CONFIG_SYSVIPC_SYSCTL */
void sem_init(void);
void msg_init(void);
@@ -96,9 +122,9 @@ struct pid_namespace *ipc_seq_pid_ns(str
#define IPC_MSG_IDS 1
#define IPC_SHM_IDS 2
-#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
-#define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
-#define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
+#define ipcid_to_idx(id) ((id) & IPCMNI_IDX_MASK)
+#define ipcid_to_seqx(id) ((id) >> IPCMNI_SEQ_SHIFT)
+#define IPCID_SEQ_MAX (INT_MAX >> IPCMNI_SEQ_SHIFT)
/* must be called with ids->rwsem acquired for writing */
int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
@@ -123,8 +149,8 @@ static inline int ipc_get_maxidx(struct
if (ids->in_use == 0)
return -1;
- if (ids->in_use == IPCMNI)
- return IPCMNI - 1;
+ if (ids->in_use == ipc_mni)
+ return ipc_mni - 1;
return ids->max_idx;
}
@@ -219,10 +245,10 @@ void free_ipcs(struct ipc_namespace *ns,
static inline int sem_check_semmni(struct ipc_namespace *ns) {
/*
- * Check semmni range [0, IPCMNI]
+ * Check semmni range [0, ipc_mni]
* semmni is the last element of sem_ctls[4] array
*/
- return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > IPCMNI))
+ return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > ipc_mni))
? -ERANGE : 0;
}
_
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
ipc-conserve-sequence-numbers-in-extended-ipcmni-mode.patch
