Messages in this thread |  | | | From | Keith Owens <> | | Subject | Re: [PATCH] Make agpsupport work with modversions | | Date | Thu, 19 Oct 2000 12:06:41 +1100 |
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On Thu, 19 Oct 2000 01:56:38 +0100 (BST), Alan Cox <alan@lxorguk.ukuu.org.uk> 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 sys_init_module()
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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