mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
synced 2025-10-31 08:26:29 +00:00
9eefe520c8
This patch proposes an alternative to the "magical positive-versus-negative number trick" Andrew complained about last week in http://lkml.org/lkml/2008/6/24/418. This had been introduced with the patches that scale msgmni to the amount of lowmem. With these patches, msgmni has a registered notification routine that recomputes msgmni value upon memory add/remove or ipc namespace creation/ removal. When msgmni is changed from user space (i.e. value written to the proc file), that notification routine is unregistered, and the way to make it registered back is to write a negative value into the proc file. This is the "magical positive-versus-negative number trick". To fix this, a new proc file is introduced: /proc/sys/kernel/auto_msgmni. This file acts as ON/OFF for msgmni automatic recomputing. With this patch, the process is the following: 1) kernel boots in "automatic recomputing mode" /proc/sys/kernel/msgmni contains the value that has been computed (depends on lowmem) /proc/sys/kernel/automatic_msgmni contains "1" 2) echo <val> > /proc/sys/kernel/msgmni . sets msg_ctlmni to <val> . de-activates automatic recomputing (i.e. if, say, some memory is added msgmni won't be recomputed anymore) . /proc/sys/kernel/automatic_msgmni now contains "0" 3) echo "0" > /proc/sys/kernel/automatic_msgmni . de-activates msgmni automatic recomputing this has the same effect as 2) except that msg_ctlmni's value stays blocked at its current value) 3) echo "1" > /proc/sys/kernel/automatic_msgmni . recomputes msgmni's value based on the current available memory size and number of ipc namespaces . re-activates automatic recomputing for msgmni. Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net> Cc: Solofo Ramangalahy <Solofo.Ramangalahy@bull.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
103 lines
2.2 KiB
C
103 lines
2.2 KiB
C
#ifndef __IPC_NAMESPACE_H__
|
|
#define __IPC_NAMESPACE_H__
|
|
|
|
#include <linux/err.h>
|
|
#include <linux/idr.h>
|
|
#include <linux/rwsem.h>
|
|
#include <linux/notifier.h>
|
|
|
|
/*
|
|
* ipc namespace events
|
|
*/
|
|
#define IPCNS_MEMCHANGED 0x00000001 /* Notify lowmem size changed */
|
|
#define IPCNS_CREATED 0x00000002 /* Notify new ipc namespace created */
|
|
#define IPCNS_REMOVED 0x00000003 /* Notify ipc namespace removed */
|
|
|
|
#define IPCNS_CALLBACK_PRI 0
|
|
|
|
|
|
struct ipc_ids {
|
|
int in_use;
|
|
unsigned short seq;
|
|
unsigned short seq_max;
|
|
struct rw_semaphore rw_mutex;
|
|
struct idr ipcs_idr;
|
|
};
|
|
|
|
struct ipc_namespace {
|
|
struct kref kref;
|
|
struct ipc_ids ids[3];
|
|
|
|
int sem_ctls[4];
|
|
int used_sems;
|
|
|
|
int msg_ctlmax;
|
|
int msg_ctlmnb;
|
|
int msg_ctlmni;
|
|
atomic_t msg_bytes;
|
|
atomic_t msg_hdrs;
|
|
int auto_msgmni;
|
|
|
|
size_t shm_ctlmax;
|
|
size_t shm_ctlall;
|
|
int shm_ctlmni;
|
|
int shm_tot;
|
|
|
|
struct notifier_block ipcns_nb;
|
|
};
|
|
|
|
extern struct ipc_namespace init_ipc_ns;
|
|
extern atomic_t nr_ipc_ns;
|
|
|
|
#ifdef CONFIG_SYSVIPC
|
|
#define INIT_IPC_NS(ns) .ns = &init_ipc_ns,
|
|
|
|
extern int register_ipcns_notifier(struct ipc_namespace *);
|
|
extern int cond_register_ipcns_notifier(struct ipc_namespace *);
|
|
extern void unregister_ipcns_notifier(struct ipc_namespace *);
|
|
extern int ipcns_notify(unsigned long);
|
|
|
|
#else /* CONFIG_SYSVIPC */
|
|
#define INIT_IPC_NS(ns)
|
|
#endif /* CONFIG_SYSVIPC */
|
|
|
|
#if defined(CONFIG_SYSVIPC) && defined(CONFIG_IPC_NS)
|
|
extern void free_ipc_ns(struct kref *kref);
|
|
extern struct ipc_namespace *copy_ipcs(unsigned long flags,
|
|
struct ipc_namespace *ns);
|
|
extern void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
|
|
void (*free)(struct ipc_namespace *,
|
|
struct kern_ipc_perm *));
|
|
|
|
static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
|
|
{
|
|
if (ns)
|
|
kref_get(&ns->kref);
|
|
return ns;
|
|
}
|
|
|
|
static inline void put_ipc_ns(struct ipc_namespace *ns)
|
|
{
|
|
kref_put(&ns->kref, free_ipc_ns);
|
|
}
|
|
#else
|
|
static inline struct ipc_namespace *copy_ipcs(unsigned long flags,
|
|
struct ipc_namespace *ns)
|
|
{
|
|
if (flags & CLONE_NEWIPC)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
return ns;
|
|
}
|
|
|
|
static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
|
|
{
|
|
return ns;
|
|
}
|
|
|
|
static inline void put_ipc_ns(struct ipc_namespace *ns)
|
|
{
|
|
}
|
|
#endif
|
|
#endif
|