Commit 91cfb2b4 authored by Nadia Derbey's avatar Nadia Derbey Committed by Linus Torvalds
Browse files

ipc: do not recompute msgmni anymore if explicitly set by user 



Make msgmni not recomputed anymore upon ipc namespace creation / removal or
memory add/remove, as soon as it has been set from userland.

As soon as msgmni is explicitly set via procfs or sysctl(), the associated
callback routine is unregistered from the ipc namespace notifier chain.

Signed-off-by: default avatarNadia Derbey <Nadia.Derbey@bull.net>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e2c284d8

ipc/ipc_sysctl.c

+41 −2
Original line number Diff line number Diff line
@@ -35,6 +35,24 @@ static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp, 
	return proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);

}



static int proc_ipc_callback_dointvec(ctl_table *table, int write,

	struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)

{

	size_t lenp_bef = *lenp;

	int rc;



	rc = proc_ipc_dointvec(table, write, filp, buffer, lenp, ppos);



	if (write && !rc && lenp_bef == *lenp)

		/*

		 * Tunable has successfully been changed from userland:

		 * disable its automatic recomputing.

		 */

		unregister_ipcns_notifier(current->nsproxy->ipc_ns);



	return rc;

}



static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,

	struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)

{
@@ -49,6 +67,7 @@ static int proc_ipc_doulongvec_minmax(ctl_table *table, int write, 
#else

#define proc_ipc_doulongvec_minmax NULL

#define proc_ipc_dointvec	   NULL

#define proc_ipc_callback_dointvec NULL

#endif



#ifdef CONFIG_SYSCTL_SYSCALL
@@ -90,8 +109,28 @@ static int sysctl_ipc_data(ctl_table *table, int __user *name, int nlen, 
	}

	return 1;

}



static int sysctl_ipc_registered_data(ctl_table *table, int __user *name,

		int nlen, void __user *oldval, size_t __user *oldlenp,

		void __user *newval, size_t newlen)

{

	int rc;



	rc = sysctl_ipc_data(table, name, nlen, oldval, oldlenp, newval,

		newlen);



	if (newval && newlen && rc > 0)

		/*

		 * Tunable has successfully been changed from userland:

		 * disable its automatic recomputing.

		 */

		unregister_ipcns_notifier(current->nsproxy->ipc_ns);



	return rc;

}

#else

#define sysctl_ipc_data NULL

#define sysctl_ipc_registered_data NULL

#endif



static struct ctl_table ipc_kern_table[] = {
@@ -137,8 +176,8 @@ static struct ctl_table ipc_kern_table[] = { 
		.data		= &init_ipc_ns.msg_ctlmni,

		.maxlen		= sizeof (init_ipc_ns.msg_ctlmni),

		.mode		= 0644,

		.proc_handler	= proc_ipc_dointvec,

		.strategy	= sysctl_ipc_data,

		.proc_handler	= proc_ipc_callback_dointvec,

		.strategy	= sysctl_ipc_registered_data,

	},

	{

		.ctl_name	= KERN_MSGMNB,

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