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由 Benjamin Herrenschmidt 提交于
This makes the 64-bit kernel use 64-bit signed integers for the counter (effectively supporting 32-bit of active count in the semaphore), thus avoiding things like overflow of the mmap_sem if you use a really crazy number of threads Note: Ideally the type in the structure should be atomic_long_t rather than "long". However, there's some nasty issues with that. It needs to be initialized statically -and- lib/rwsem.c does things like sem->count = RWSEM_UNLOCKED_VALUE; Now, if you mix in the fact that atomic_* types are actually structures with one member and note typedefs of a scalar, it makes its really nasty. So I stuck to what we did before using a long and casts for now. Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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