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

[safe/jmp/linux-2.6] / ipc / ipc_sysctl.c

diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index 7f4235b..d12ff5c 100644 (file)
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -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,