Andrew Morton wrote:
On Mon, 11 Feb 2008 15:16:54 +0100 Nadia.Derbey@xxxxxxxx wrote:[PATCH 08/08] This patch is the enhancement as asked for by Yasunori: if msgmni is set to a negative value, register it back into the ipcns notifier chain. A new interface has been added to the notification mechanism: notifier_chain_cond_register() registers a notifier block only if not already registered. With that new interface we avoid taking care of the states changes in procfs. ... 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; - rc = proc_ipc_dointvec(table, write, filp, buffer, lenp, ppos); + 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 from userland: - * disable its automatic recomputing. - */ - unregister_ipcns_notifier(current->nsproxy->ipc_ns); + tunable_set_callback(*((int *)(ipc_table.data))); return rc; } @@ -119,12 +142,14 @@ static int sysctl_ipc_registered_data(ct 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: - * disable its automatic recomputing. + * Tunable has successfully been changed from userland */ - unregister_ipcns_notifier(current->nsproxy->ipc_ns); + int *data = get_ipc(table); + + tunable_set_callback(*data); + } return rc; }hm, what's happening here? We take a local copy of the caller's ctl_table and then pass that into proc_dointvec(). Is that as hacky as it seems??
Well, the caller's ctl_table contains the tunables addresses for the init namspeace in its .data fields. While what needs to be passed in to proc_dointvec() is the tunable address in the caller's namespace. Since all the fields in ipc_kern_table[] are ok but the .data one, imho it's correct to store it in a local copy and change the data field to the appropirate one, before passing it to proc_dointvec().
Regards, Nadia _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
