On Mon, 2007-07-23 at 19:59 +0200, Adrian Bunk wrote:
> On Mon, Jul 23, 2007 at 09:05:54AM -0700, Nelson, Shannon wrote:
> > Gabriel C [mailto:[EMAIL PROTECTED] 
> > >
> > >Hi,
> > >
> > >I got this warning on current git using gcc 4.2.1 :
> > >
> > >...
> > >
> > >drivers/dma/ioatdma.c: In function 'ioat_init_module':
> > >drivers/dma/ioatdma.c:816: warning: the address of 
> > >'__this_module' will always evaluate as 'true'
> >...
> 
> I'm less interested in why this gives a warning, more interesting is the 
> code:
>         __unsafe(THIS_MODULE);
> 
> @Rusty:
> As far as I understand it, __unsafe() wasn't intended for such a usage, 
> and simply not providing an exit function would be the right solution?
> If this is true, and since the MOD_INC_USE_COUNT compat code is long 
> gone, shouldn't we be able to completely remove __unsafe() and the 
> struct member "unsafe"?

Yes, indeed, something like this:
==
Remove "unsafe" from module struct

Adrian Bunk points out that "unsafe" was used to mark modules touched by
the deprecated MOD_INC_USE_COUNT interface, which has long gone.  It's
time to remove the member from the module structure, as well.

If you want a module which can't unload, don't register an exit
function.

Signed-off-by: Rusty Russell <[EMAIL PROTECTED]>

diff -r d7af727512fd drivers/dma/ioatdma.c
--- a/drivers/dma/ioatdma.c     Tue Jul 24 08:30:05 2007 +1000
+++ b/drivers/dma/ioatdma.c     Tue Jul 24 09:11:11 2007 +1000
@@ -811,18 +811,17 @@ MODULE_AUTHOR("Intel Corporation");
 
 static int __init ioat_init_module(void)
 {
-       /* it's currently unsafe to unload this module */
-       /* if forced, worst case is that rmmod hangs */
-       __unsafe(THIS_MODULE);
-
        return pci_register_driver(&ioat_pci_driver);
 }
 
 module_init(ioat_init_module);
 
+/* it's currently unsafe to unload this module */
+#if 0
 static void __exit ioat_exit_module(void)
 {
        pci_unregister_driver(&ioat_pci_driver);
 }
 
 module_exit(ioat_exit_module);
+#endif
diff -r d7af727512fd drivers/dma/iop-adma.c
--- a/drivers/dma/iop-adma.c    Tue Jul 24 08:30:05 2007 +1000
+++ b/drivers/dma/iop-adma.c    Tue Jul 24 09:11:30 2007 +1000
@@ -1446,21 +1446,20 @@ static struct platform_driver iop_adma_d
 
 static int __init iop_adma_init (void)
 {
-       /* it's currently unsafe to unload this module */
-       /* if forced, worst case is that rmmod hangs */
-       __unsafe(THIS_MODULE);
-
        return platform_driver_register(&iop_adma_driver);
 }
 
+/* it's currently unsafe to unload this module */
+#if 0
 static void __exit iop_adma_exit (void)
 {
        platform_driver_unregister(&iop_adma_driver);
        return;
 }
+module_exit(iop_adma_exit);
+#endif
 
 module_init(iop_adma_init);
-module_exit(iop_adma_exit);
 
 MODULE_AUTHOR("Intel Corporation");
 MODULE_DESCRIPTION("IOP ADMA Engine Driver");
diff -r d7af727512fd include/linux/module.h
--- a/include/linux/module.h    Tue Jul 24 08:30:05 2007 +1000
+++ b/include/linux/module.h    Tue Jul 24 09:00:19 2007 +1000
@@ -312,9 +312,6 @@ struct module
        /* Arch-specific module values */
        struct mod_arch_specific arch;
 
-       /* Am I unsafe to unload? */
-       int unsafe;
-
        unsigned int taints;    /* same bits as kernel:tainted */
 
 #ifdef CONFIG_GENERIC_BUG
@@ -441,16 +438,6 @@ static inline void __module_get(struct m
        __mod ? __mod->name : "kernel";         \
 })
 
-#define __unsafe(mod)                                                       \
-do {                                                                        \
-       if (mod && !(mod)->unsafe) {                                         \
-               printk(KERN_WARNING                                          \
-                      "Module %s cannot be unloaded due to unsafe usage in" \
-                      " %s:%u\n", (mod)->name, __FILE__, __LINE__);         \
-               (mod)->unsafe = 1;                                           \
-       }                                                                    \
-} while(0)
-
 /* For kallsyms to ask for address resolution.  NULL means not found. */
 const char *module_address_lookup(unsigned long addr,
                                  unsigned long *symbolsize,
@@ -518,8 +505,6 @@ static inline void module_put(struct mod
 
 #define module_name(mod) "kernel"
 
-#define __unsafe(mod)
-
 /* For kallsyms to ask for address resolution.  NULL means not found. */
 static inline const char *module_address_lookup(unsigned long addr,
                                                unsigned long *symbolsize,
diff -r d7af727512fd kernel/module.c
--- a/kernel/module.c   Tue Jul 24 08:30:05 2007 +1000
+++ b/kernel/module.c   Tue Jul 24 09:00:58 2007 +1000
@@ -692,8 +692,7 @@ sys_delete_module(const char __user *nam
        }
 
        /* If it has an init func, it must have an exit func to unload */
-       if ((mod->init != NULL && mod->exit == NULL)
-           || mod->unsafe) {
+       if (mod->init && !mod->exit) {
                forced = try_force_unload(flags);
                if (!forced) {
                        /* This module can't be removed */
@@ -739,11 +738,6 @@ static void print_unload_info(struct seq
        list_for_each_entry(use, &mod->modules_which_use_me, list) {
                printed_something = 1;
                seq_printf(m, "%s,", use->module_which_uses->name);
-       }
-
-       if (mod->unsafe) {
-               printed_something = 1;
-               seq_printf(m, "[unsafe],");
        }
 
        if (mod->init != NULL && mod->exit == NULL) {
@@ -2012,15 +2006,10 @@ sys_init_module(void __user *umod,
                    buggy refcounters. */
                mod->state = MODULE_STATE_GOING;
                synchronize_sched();
-               if (mod->unsafe)
-                       printk(KERN_ERR "%s: module is now stuck!\n",
-                              mod->name);
-               else {
-                       module_put(mod);
-                       mutex_lock(&module_mutex);
-                       free_module(mod);
-                       mutex_unlock(&module_mutex);
-               }
+               module_put(mod);
+               mutex_lock(&module_mutex);
+               free_module(mod);
+               mutex_unlock(&module_mutex);
                return ret;
        }
 
diff -r d7af727512fd net/sctp/protocol.c
--- a/net/sctp/protocol.c       Tue Jul 24 08:30:05 2007 +1000
+++ b/net/sctp/protocol.c       Tue Jul 24 09:12:43 2007 +1000
@@ -1176,7 +1176,6 @@ SCTP_STATIC __init int sctp_init(void)
        if (status)
                goto err_v6_add_protocol;
 
-       __unsafe(THIS_MODULE);
        status = 0;
 out:
        return status;
@@ -1216,6 +1215,7 @@ err_chunk_cachep:
        goto out;
 }
 
+#if 0
 /* Exit handler for the SCTP protocol.  */
 SCTP_STATIC __exit void sctp_exit(void)
 {
@@ -1263,9 +1263,10 @@ SCTP_STATIC __exit void sctp_exit(void)
 
        proto_unregister(&sctp_prot);
 }
+module_exit(sctp_exit);
+#endif
 
 module_init(sctp_init);
-module_exit(sctp_exit);
 
 /*
  * __stringify doesn't likes enums, so use IPPROTO_SCTP value (132) directly.


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