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![Manfred Spraul](/assets/img/avatar_default.png)
SysV can be abused to allocate locked kernel memory. For most systems, a small limit doesn't make sense, see the discussion with regards to SHMMAX. Therefore: increase MSGMNI to the maximum supported. And: If we ignore the risk of locking too much memory, then an automatic scaling of MSGMNI doesn't make sense. Therefore the logic can be removed. The code preserves auto_msgmni to avoid breaking any user space applications that expect that the value exists. Notes: 1) If an administrator must limit the memory allocations, then he can set MSGMNI as necessary. Or he can disable sysv entirely (as e.g. done by Android). 2) MSGMAX and MSGMNB are intentionally not increased, as these values are used to control latency vs. throughput: If MSGMNB is large, then msgsnd() just returns and more messages can be queued before a task switch to a task that calls msgrcv() is forced. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
224 lines
5.4 KiB
C
224 lines
5.4 KiB
C
/*
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* Copyright (C) 2007
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*
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* Author: Eric Biederman <ebiederm@xmision.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*/
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#include <linux/module.h>
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#include <linux/ipc.h>
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#include <linux/nsproxy.h>
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#include <linux/sysctl.h>
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#include <linux/uaccess.h>
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#include <linux/ipc_namespace.h>
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#include <linux/msg.h>
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#include "util.h"
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static void *get_ipc(struct ctl_table *table)
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{
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char *which = table->data;
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struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
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which = (which - (char *)&init_ipc_ns) + (char *)ipc_ns;
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return which;
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}
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#ifdef CONFIG_PROC_SYSCTL
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static int proc_ipc_dointvec(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table ipc_table;
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memcpy(&ipc_table, table, sizeof(ipc_table));
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ipc_table.data = get_ipc(table);
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return proc_dointvec(&ipc_table, write, buffer, lenp, ppos);
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}
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static int proc_ipc_dointvec_minmax(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table ipc_table;
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memcpy(&ipc_table, table, sizeof(ipc_table));
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ipc_table.data = get_ipc(table);
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return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
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}
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static int proc_ipc_dointvec_minmax_orphans(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ipc_namespace *ns = current->nsproxy->ipc_ns;
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int err = proc_ipc_dointvec_minmax(table, write, buffer, lenp, ppos);
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if (err < 0)
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return err;
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if (ns->shm_rmid_forced)
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shm_destroy_orphaned(ns);
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return err;
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}
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static int proc_ipc_doulongvec_minmax(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table ipc_table;
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memcpy(&ipc_table, table, sizeof(ipc_table));
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ipc_table.data = get_ipc(table);
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return proc_doulongvec_minmax(&ipc_table, write, buffer,
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lenp, ppos);
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}
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static int proc_ipc_auto_msgmni(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table ipc_table;
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int dummy = 0;
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memcpy(&ipc_table, table, sizeof(ipc_table));
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ipc_table.data = &dummy;
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if (write)
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pr_info_once("writing to auto_msgmni has no effect");
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return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
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}
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#else
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#define proc_ipc_doulongvec_minmax NULL
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#define proc_ipc_dointvec NULL
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#define proc_ipc_dointvec_minmax NULL
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#define proc_ipc_dointvec_minmax_orphans NULL
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#define proc_ipc_auto_msgmni NULL
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#endif
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static int zero;
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static int one = 1;
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static int int_max = INT_MAX;
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static struct ctl_table ipc_kern_table[] = {
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{
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.procname = "shmmax",
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.data = &init_ipc_ns.shm_ctlmax,
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.maxlen = sizeof(init_ipc_ns.shm_ctlmax),
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.mode = 0644,
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.proc_handler = proc_ipc_doulongvec_minmax,
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},
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{
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.procname = "shmall",
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.data = &init_ipc_ns.shm_ctlall,
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.maxlen = sizeof(init_ipc_ns.shm_ctlall),
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.mode = 0644,
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.proc_handler = proc_ipc_doulongvec_minmax,
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},
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{
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.procname = "shmmni",
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.data = &init_ipc_ns.shm_ctlmni,
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.maxlen = sizeof(init_ipc_ns.shm_ctlmni),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec,
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},
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{
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.procname = "shm_rmid_forced",
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.data = &init_ipc_ns.shm_rmid_forced,
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.maxlen = sizeof(init_ipc_ns.shm_rmid_forced),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax_orphans,
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.extra1 = &zero,
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.extra2 = &one,
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},
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{
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.procname = "msgmax",
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.data = &init_ipc_ns.msg_ctlmax,
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.maxlen = sizeof(init_ipc_ns.msg_ctlmax),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = &zero,
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.extra2 = &int_max,
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},
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{
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.procname = "msgmni",
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.data = &init_ipc_ns.msg_ctlmni,
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.maxlen = sizeof(init_ipc_ns.msg_ctlmni),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = &zero,
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.extra2 = &int_max,
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},
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{
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.procname = "auto_msgmni",
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.data = NULL,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_ipc_auto_msgmni,
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.extra1 = &zero,
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.extra2 = &one,
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},
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{
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.procname = "msgmnb",
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.data = &init_ipc_ns.msg_ctlmnb,
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.maxlen = sizeof(init_ipc_ns.msg_ctlmnb),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = &zero,
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.extra2 = &int_max,
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},
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{
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.procname = "sem",
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.data = &init_ipc_ns.sem_ctls,
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.maxlen = 4*sizeof(int),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec,
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},
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#ifdef CONFIG_CHECKPOINT_RESTORE
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{
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.procname = "sem_next_id",
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.data = &init_ipc_ns.ids[IPC_SEM_IDS].next_id,
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.maxlen = sizeof(init_ipc_ns.ids[IPC_SEM_IDS].next_id),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = &zero,
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.extra2 = &int_max,
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},
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{
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.procname = "msg_next_id",
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.data = &init_ipc_ns.ids[IPC_MSG_IDS].next_id,
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.maxlen = sizeof(init_ipc_ns.ids[IPC_MSG_IDS].next_id),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = &zero,
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.extra2 = &int_max,
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},
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{
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.procname = "shm_next_id",
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.data = &init_ipc_ns.ids[IPC_SHM_IDS].next_id,
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.maxlen = sizeof(init_ipc_ns.ids[IPC_SHM_IDS].next_id),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = &zero,
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.extra2 = &int_max,
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},
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#endif
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{}
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};
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static struct ctl_table ipc_root_table[] = {
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{
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.procname = "kernel",
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.mode = 0555,
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.child = ipc_kern_table,
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},
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{}
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};
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static int __init ipc_sysctl_init(void)
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{
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register_sysctl_table(ipc_root_table);
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return 0;
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}
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device_initcall(ipc_sysctl_init);
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