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SubjectRe: [PATCH] Make agpsupport work with modversions
On Thu, 19 Oct 2000 01:56:38 +0100 (BST), 
Alan Cox <> wrote:
>Keith Owens wrote
>> modprobe would attempt to satisfy weak external references as if they
>> were normal references, including all the module dependency chains and
>> reference counts. If the reference cannot be satisfied, it is set to
>> zero instead of causing an error. No changes to load/unload.
>I dont believe modprobe can do this race free in userspace

Module dependency checking in userspace has always been racy. A is
being loaded and needs a symbol from B. B was loaded at the start of
insmod so the symbol was resolved. By the time A is actually loaded, B
has been removed, userspace race. This is checked for in

printk(KERN_ERR "init_module: found dependency that is "
"(no longer?) a module.\n");

Making some of the external references weak makes no difference.
Either they are resolved to a module by insmod and checked by
sys_init_module() or insmod replaces the reference with NULL.

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