Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH] kernel/module.c: Free lock-classes if parse_args failed | Date | Thu, 22 Jan 2015 11:10:30 +1030 |
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Andrey Tsyvarev <tsyvarev@ispras.ru> writes: > 21.01.2015 4:40, Rusty Russell пишет: >> Andrey Tsyvarev <tsyvarev@ispras.ru> writes: >>> 20.01.2015 9:37, Rusty Russell пишет: >>>> Andrey Tsyvarev <tsyvarev@ispras.ru> writes: >>>>> parse_args call module parameters' .set handlers, which may use locks defined in the module. >>>>> So, these classes should be freed in case parse_args returns error(e.g. due to incorrect parameter passed). >>>> Thanks, this seems right. Applied. >>>> >>>> But this makes me ask: where is lockdep_free_key_range() called on the >>>> module init code? It doesn't seem to be at all... >>> As I understand, locks are not allowed to be defined in the module init >>> section. So, no needs to call lockdep_free_key_range() for it. >>> This has a sense: objects from that section are allowed to be used only >>> by module->init() function. But a single function call doesn't require >>> any synchronization wrt itself. >> I don't know that we have any __initdata locks; it would be really >> weird. >> >> But change 'static DEFINE_MUTEX(mutex_param);' to 'static __initdata >> DEFINE_MUTEX(mutex_param);' to test. > Compiler warns about sections mismatch, but the test works. > > According to lockdep_free_key_range() code, lock class is cleared not > only according to > its key(which is equal to lock address in the case of static lock) but > also according to its name.
What happens if you later register another lock at that address, since the memory is freed?
A quick grep revealed no __initdata locks in the kernel, so I don't think we care anyway.
Cheers, Rusty.
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