To follow up on this, to make the existing version check system continue to work, it would only check those modules that reference the "struct modconfigopts", either by way of a compiler option on the macro, or just recommendation that coder create an external reference to whatever is needed to make the modversions create a reference to it.
On Sat, Feb 13, 2016 at 12:13 AM, David F. <[email protected]> wrote: > After sending the below, I realized that if someone doesn't want to > have to dereference a pointer it could still be done the same way and > just omitting the member variable (options). You would just always > allocate (sizeof (struct module)+sizeof(struct modconfigopts)) and to > access the options, use a different macro: #define MOD_OPT(m) ((struct > modconfigopts*)((m)+1)) --or-- #define MOD_OPT(m) ((struct > modconfigopts*)((int8_t*)(m)+sizeof(*m))) > example of when an optional item is reference: > MOD_OPT(THIS_MODULE)->param_lock > > now you don't have any dereferencing of the pointer. > > > On Fri, Feb 12, 2016 at 11:45 PM, David F. <[email protected]> wrote: >> While creating a linux module that should be usable across a wide >> array of linux versions and builds, I've run into struct modules >> (THIS_MODULE) being a problem. It's the only internal struct accessed >> as a requirement to struct block_device_operations .owner. It's a >> bit annoying for this module to be rejected for nothing it has any >> interest in using. So I was thinking of a quick solution but don't >> want to waste my time if people will resist it (not sure when I'll >> have time to do it, but should be able to do it quickly once i'd have >> all the source local). The idea is: >> >> Take all #if defines out of the struct module and place them in a >> separate struct (struct modconfigopts). Place a single member >> variable at the end of struct modules as void * (void *options) to >> access the options. Have a single macro to access the options member >> variable for the internal code that access it (#define MOD_OPT(v) >> ((struct modconfigopts*)(v)). So internal code would use >> module->MOD_OPT(options)->param_lock for example. >> >> When the module structure is created, it would initialize the options >> member variable (the memory allocated (sizeof(struct >> module)+sizeof(struct modconfigopts)) could be contiguous so it's like >> one big structure, then cleanup would be the same). >> >> Doing this should then allow "external" modules that don't need access >> to the "internal" config options to continue to load and work across a >> much greater range of Linux distributions. >> >> What do you think?
