Re: [PATCH v1 11/15] arm/futex: UP futex_atomic_op_inuser() relies on disabled preemption

Sebastian Andrzej Siewior
2015-05-12T19:01:34Z

* David Hildenbrand | 2015-05-11 17:52:16 [+0200]:

>The !CONFIG_SMP implementation of futex_atomic_op_inuser() seems to rely
>on disabled preemption to guarantee mutual exclusion.

Yes, this is what the code looks like. It is more the requirement for
ldrex/strex opcodes which are ARMv6+ and so is SMP support (here).
Documentation wise you could replace CONFIG_SMP by
__LINUX_ARM_ARCH__ >= 6
in a later patch if you like. This would be more in-sync with
arch/arm/include/asm/cmpxchg.h :)

Sebastian