Merge git://git.infradead.org/~dwmw2/random-2.6

[pandora-kernel.git] / ipc / ipc_sysctl.c

diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index 7f4235b..69bc859 100644 (file)
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -15,6 +15,8 @@
 #include <linux/sysctl.h>
 #include <linux/uaccess.h>
 #include <linux/ipc_namespace.h>
+#include <linux/msg.h>
+#include "util.h"
 
 static void *get_ipc(ctl_table *table)
 {
@@ -24,6 +26,29 @@ static void *get_ipc(ctl_table *table)
        return which;
 }
 
+/*
+ * Routine that is called when the file "auto_msgmni" has successfully been
+ * written.
+ * Two values are allowed:
+ * 0: unregister msgmni's callback routine from the ipc namespace notifier
+ *    chain. This means that msgmni won't be recomputed anymore upon memory
+ *    add/remove or ipc namespace creation/removal.
+ * 1: register back the callback routine.
+ */
+static void ipc_auto_callback(int val)
+{
+       if (!val)
+               unregister_ipcns_notifier(current->nsproxy->ipc_ns);
+       else {
+               /*
+                * Re-enable automatic recomputing only if not already
+                * enabled.
+                */
+               recompute_msgmni(current->nsproxy->ipc_ns);
+               cond_register_ipcns_notifier(current->nsproxy->ipc_ns);
+       }
+}
+
 #ifdef CONFIG_PROC_FS
 static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp,
        void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -35,6 +60,29 @@ 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)
+{
+       struct ctl_table ipc_table;
+       size_t lenp_bef = *lenp;
+       int rc;
+
+       memcpy(&ipc_table, table, sizeof(ipc_table));
+       ipc_table.data = get_ipc(table);
+
+       rc = proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);
+
+       if (write && !rc && lenp_bef == *lenp)
+               /*
+                * Tunable has successfully been changed by hand. Disable its
+                * automatic adjustment. This simply requires unregistering
+                * the notifiers that trigger recalculation.
+                */
+               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)
 {
@@ -46,9 +94,39 @@ static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
                                        lenp, ppos);
 }
 
+static int proc_ipcauto_dointvec_minmax(ctl_table *table, int write,
+       struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+       struct ctl_table ipc_table;
+       size_t lenp_bef = *lenp;
+       int oldval;
+       int rc;
+
+       memcpy(&ipc_table, table, sizeof(ipc_table));
+       ipc_table.data = get_ipc(table);
+       oldval = *((int *)(ipc_table.data));
+
+       rc = proc_dointvec_minmax(&ipc_table, write, filp, buffer, lenp, ppos);
+
+       if (write && !rc && lenp_bef == *lenp) {
+               int newval = *((int *)(ipc_table.data));
+               /*
+                * The file "auto_msgmni" has correctly been set.
+                * React by (un)registering the corresponding tunable, if the
+                * value has changed.
+                */
+               if (newval != oldval)
+                       ipc_auto_callback(newval);
+       }
+
+       return rc;
+}
+
 #else
 #define proc_ipc_doulongvec_minmax NULL
 #define proc_ipc_dointvec         NULL
+#define proc_ipc_callback_dointvec NULL
+#define proc_ipcauto_dointvec_minmax NULL
 #endif
 
 #ifdef CONFIG_SYSCTL_SYSCALL
@@ -90,10 +168,32 @@ 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
+                */
+               unregister_ipcns_notifier(current->nsproxy->ipc_ns);
+
+       return rc;
+}
 #else
 #define sysctl_ipc_data NULL
+#define sysctl_ipc_registered_data NULL
 #endif
 
+static int zero;
+static int one = 1;
+
 static struct ctl_table ipc_kern_table[] = {
        {
                .ctl_name       = KERN_SHMMAX,
@@ -137,8 +237,8 @@ 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,
@@ -158,6 +258,16 @@ static struct ctl_table ipc_kern_table[] = {
                .proc_handler   = proc_ipc_dointvec,
                .strategy       = sysctl_ipc_data,
        },
+       {
+               .ctl_name       = CTL_UNNUMBERED,
+               .procname       = "auto_msgmni",
+               .data           = &init_ipc_ns.auto_msgmni,
+               .maxlen         = sizeof(int),
+               .mode           = 0644,
+               .proc_handler   = proc_ipcauto_dointvec_minmax,
+               .extra1         = &zero,
+               .extra2         = &one,
+       },
        {}
 };