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SubjectRe: Several Misc SCSI updates...
On Sun, Nov 17, 2002 at 04:55:26PM -0500, Alexander Viro wrote:
>
>
> On Sun, 17 Nov 2002, Linus Torvalds wrote:
>
> >
> > On Sun, 17 Nov 2002, Doug Ledford wrote:
> > >
> > > Won't work. module->live is what Rusty uses to indicate that the module
> > > is in the process of unloading, which is when we *do* want the attempt to
> > > module_get() to fail.
> >
> > That's fine, as long as "module_get()" is the only thing that cares. Just
> > make it go "live" early as you indicate, and everybody should be happy. I
> > certainly agree that it should be illegal to do more module_get()'s once
> > we've already started unloading..
>
> On the unload side it's OK. module_get() also breaks during _init_ and that's
> the problem. IOW, you'll need to make every block device driver to set ->live
> manually. Smells like a wrong API...

This is the patch I just put into my tree (beware cut-n-paste breakage is
in effect, but Linus should have the change in his tree momentarily
anyway):

diff -Nru a/kernel/module.c b/kernel/module.c
--- a/kernel/module.c Sun Nov 17 17:02:48 2002
+++ b/kernel/module.c Sun Nov 17 17:02:48 2002
@@ -1058,6 +1058,15 @@
list_add(&mod->extable.list, &extables);
spin_unlock_irq(&modlist_lock);

+ /* Note, setting the mod->live to 1 here is safe because we haven't
+ * linked the module into the system's kernel symbol table yet,
+ * which means that the only way any other kernel code can call
+ * into this module right now is if this module hands out entry
+ * pointers to the other code. We assume that no module hands out
+ * entry pointers to the rest of the kernel unless it is ready to
+ * have them used.
+ */
+ mod->live = 1;
/* Start the module */
ret = mod->init ? mod->init() : 0;
if (ret < 0) {
@@ -1070,9 +1079,10 @@
/* Mark it "live" so that they can force
deletion later, and we don't keep getting
woken on every decrement. */
- mod->live = 1;
- } else
+ } else {
+ mod->live = 0;
free_module(mod);
+ }
up(&module_mutex);
return ret;
}
@@ -1087,7 +1097,6 @@
mod->module_init = NULL;

/* All ok! */
- mod->live = 1;
up(&module_mutex);
return 0;
}

--
Doug Ledford <dledford@redhat.com> 919-754-3700 x44233
Red Hat, Inc.
1801 Varsity Dr.
Raleigh, NC 27606

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