diff options
| -rw-r--r-- | include/linux/ipc_namespace.h | 3 | ||||
| -rw-r--r-- | ipc/ipc_sysctl.c | 72 | ||||
| -rw-r--r-- | ipc/ipcns_notifier.c | 20 |
3 files changed, 76 insertions, 19 deletions
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h index ea6c18a..ea330f9 100644 --- a/include/linux/ipc_namespace.h +++ b/include/linux/ipc_namespace.h @@ -36,6 +36,7 @@ struct ipc_namespace { int msg_ctlmni; atomic_t msg_bytes; atomic_t msg_hdrs; + int auto_msgmni; size_t shm_ctlmax; size_t shm_ctlall; @@ -53,7 +54,7 @@ extern atomic_t nr_ipc_ns; extern int register_ipcns_notifier(struct ipc_namespace *); extern int cond_register_ipcns_notifier(struct ipc_namespace *); -extern int unregister_ipcns_notifier(struct ipc_namespace *); +extern void unregister_ipcns_notifier(struct ipc_namespace *); extern int ipcns_notify(unsigned long); #else /* CONFIG_SYSVIPC */ diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c index d349746..69bc859 100644 --- a/ipc/ipc_sysctl.c +++ b/ipc/ipc_sysctl.c @@ -27,15 +27,17 @@ static void *get_ipc(ctl_table *table) } /* - * Routine that is called when a tunable has successfully been changed by - * hand and it has a callback routine registered on the ipc namespace notifier - * chain: we don't want such tunables to be recomputed anymore upon memory - * add/remove or ipc namespace creation/removal. - * They can come back to a recomputable state by being set to a <0 value. + * 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 tunable_set_callback(int val) +static void ipc_auto_callback(int val) { - if (val >= 0) + if (!val) unregister_ipcns_notifier(current->nsproxy->ipc_ns); else { /* @@ -71,7 +73,12 @@ static int proc_ipc_callback_dointvec(ctl_table *table, int write, rc = proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos); if (write && !rc && lenp_bef == *lenp) - tunable_set_callback(*((int *)(ipc_table.data))); + /* + * 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; } @@ -87,10 +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 @@ -142,14 +178,11 @@ static int sysctl_ipc_registered_data(ctl_table *table, int __user *name, rc = sysctl_ipc_data(table, name, nlen, oldval, oldlenp, newval, newlen); - if (newval && newlen && rc > 0) { + if (newval && newlen && rc > 0) /* * Tunable has successfully been changed from userland */ - int *data = get_ipc(table); - - tunable_set_callback(*data); - } + unregister_ipcns_notifier(current->nsproxy->ipc_ns); return rc; } @@ -158,6 +191,9 @@ static int sysctl_ipc_registered_data(ctl_table *table, int __user *name, #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, @@ -222,6 +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, + }, {} }; diff --git a/ipc/ipcns_notifier.c b/ipc/ipcns_notifier.c index 70ff091..b9b31a4 100644 --- a/ipc/ipcns_notifier.c +++ b/ipc/ipcns_notifier.c @@ -55,25 +55,35 @@ static int ipcns_callback(struct notifier_block *self, int register_ipcns_notifier(struct ipc_namespace *ns) { + int rc; + memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb)); ns->ipcns_nb.notifier_call = ipcns_callback; ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI; - return blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb); + rc = blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb); + if (!rc) + ns->auto_msgmni = 1; + return rc; } int cond_register_ipcns_notifier(struct ipc_namespace *ns) { + int rc; + memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb)); ns->ipcns_nb.notifier_call = ipcns_callback; ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI; - return blocking_notifier_chain_cond_register(&ipcns_chain, + rc = blocking_notifier_chain_cond_register(&ipcns_chain, &ns->ipcns_nb); + if (!rc) + ns->auto_msgmni = 1; + return rc; } -int unregister_ipcns_notifier(struct ipc_namespace *ns) +void unregister_ipcns_notifier(struct ipc_namespace *ns) { - return blocking_notifier_chain_unregister(&ipcns_chain, - &ns->ipcns_nb); + blocking_notifier_chain_unregister(&ipcns_chain, &ns->ipcns_nb); + ns->auto_msgmni = 0; } int ipcns_notify(unsigned long val) |
