Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 4 Nov 2002 19:45:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 4 Nov 2002 19:45:41 -0500 Received: from dp.samba.org ([66.70.73.150]:26559 "EHLO lists.samba.org") by vger.kernel.org with ESMTP id ; Mon, 4 Nov 2002 19:45:38 -0500 From: Rusty Russell Subject: [PATCH] Module loader against 2.5.46: 7/9 To: torvalds@transmeta.com Cc: linux-kernel@vger.kernel.org In-reply-to: Your message of "Tue, 05 Nov 2002 11:21:48 +1100." <20021105002215.8EEE22C0F8@lists.samba.org> Date: Tue, 05 Nov 2002 11:41:25 +1100 Message-Id: <20021105005213.DF59B2C0B6@lists.samba.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5230 Lines: 163 Forced unload for modules "rmmod -f". Taints the kernel, but sometimes when you're developing or desperate, it's the best option. Note that normal module unloading is still supported: this allows you to unload modules with non-zero refcounts, no unload routine, or which have been marked "unsafe" by detecting racy usages. Linus, please apply, Rusty. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. Name: Forced Module Unload Author: Rusty Russell Status: Experimental Depends: Module/module.patch.gz D: Allows the (very dangerous!) "rmmod -f" for kernel developers and D: desperate people. diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9002-linux-2.5.45/include/linux/kernel.h .9002-linux-2.5.45.updated/include/linux/kernel.h --- .9002-linux-2.5.45/include/linux/kernel.h 2002-10-19 17:48:10.000000000 +1000 +++ .9002-linux-2.5.45.updated/include/linux/kernel.h 2002-11-01 11:52:04.000000000 +1100 @@ -102,6 +102,7 @@ extern const char *print_tainted(void); #define TAINT_PROPRIETORY_MODULE (1<<0) #define TAINT_FORCED_MODULE (1<<1) #define TAINT_UNSAFE_SMP (1<<2) +#define TAINT_FORCED_RMMOD (1<<3) extern void dump_stack(void); diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9002-linux-2.5.45/init/Kconfig .9002-linux-2.5.45.updated/init/Kconfig --- .9002-linux-2.5.45/init/Kconfig 2002-11-01 11:51:08.000000000 +1100 +++ .9002-linux-2.5.45.updated/init/Kconfig 2002-11-01 11:55:00.000000000 +1100 @@ -125,6 +125,16 @@ config MODULE_UNLOAD anyway), which makes your kernel slightly smaller and simpler. If unsure, say Y. +config MODULE_FORCE_UNLOAD + bool "Forced module unloading" + depends on MODULES && EXPERIMENTAL + help + This option allows you to force a module to unload, even if the + kernel believes it is unsafe: the kernel will remove the module + without waiting for anyone to stop using it (using the -f option to + rmmod). This is mainly for kernel developers and desparate users. + If unsure, say N. + config KMOD bool "Kernel module loader" depends on MODULES diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9002-linux-2.5.45/kernel/module.c .9002-linux-2.5.45.updated/kernel/module.c --- .9002-linux-2.5.45/kernel/module.c 2002-11-01 11:51:08.000000000 +1100 +++ .9002-linux-2.5.45.updated/kernel/module.c 2002-11-01 11:52:04.000000000 +1100 @@ -335,12 +335,24 @@ static unsigned int module_refcount(stru /* This exists whether we can unload or not */ static void free_module(struct module *mod); +#ifdef CONFIG_MODULE_FORCE_UNLOAD +static inline int try_force(unsigned int flags) +{ + return (flags & O_TRUNC); +} +#else +static inline int try_force(unsigned int flags) +{ + return 0; +} +#endif /* CONFIG_MODULE_FORCE_UNLOAD */ + asmlinkage long sys_delete_module(const char *name_user, unsigned int flags) { struct module *mod; char name[MODULE_NAME_LEN]; - int ret; + int ret, forced = 0; if (!capable(CAP_SYS_MODULE)) return -EPERM; @@ -358,24 +370,29 @@ sys_delete_module(const char *name_user, goto out; } + if (!list_empty(&mod->modules_which_use_me)) { + /* Other modules depend on us: get rid of them first. */ + ret = -EWOULDBLOCK; + goto out; + } + /* Already dying? */ if (!mod->live) { + /* FIXME: if (force), slam module count and wake up + waiter --RR */ DEBUGP("%s already dying\n", mod->name); ret = -EBUSY; goto out; } if (!mod->exit || mod->unsafe) { - /* This module can't be removed */ - ret = -EBUSY; - goto out; - } - if (!list_empty(&mod->modules_which_use_me)) { - /* Other modules depend on us: get rid of them first. */ - ret = -EWOULDBLOCK; - goto out; + forced = try_force(flags); + if (!forced) { + /* This module can't be removed */ + ret = -EBUSY; + goto out; + } } - /* Stop the machine so refcounts can't move: irqs disabled. */ DEBUGP("Stopping refcounts...\n"); ret = stop_refcounts(); @@ -383,9 +400,11 @@ sys_delete_module(const char *name_user, goto out; /* If it's not unused, quit unless we are told to block. */ - if ((flags & O_NONBLOCK) && module_refcount(mod) != 0) - ret = -EWOULDBLOCK; - else { + if ((flags & O_NONBLOCK) && module_refcount(mod) != 0) { + forced = try_force(flags); + if (!forced) + ret = -EWOULDBLOCK; + } else { mod->waiter = current; mod->live = 0; } @@ -394,6 +413,9 @@ sys_delete_module(const char *name_user, if (ret != 0) goto out; + if (forced) + goto destroy; + /* Since we might sleep for some time, drop the semaphore first */ up(&module_mutex); for (;;) { @@ -408,10 +430,11 @@ sys_delete_module(const char *name_user, DEBUGP("Regrabbing mutex...\n"); down(&module_mutex); + destroy: /* Final destruction now noone is using it. */ - mod->exit(); + if (mod->exit) + mod->exit(); free_module(mod); - ret = 0; out: up(&module_mutex); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/