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ARC: spinlock: Document the EX based spin_unlock
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
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@ -296,6 +296,12 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock)
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*/
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smp_mb();
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/*
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* EX is not really required here, a simple STore of 0 suffices.
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* However this causes tasklist livelocks in SystemC based SMP virtual
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* platforms where the systemc core scheduler uses EX as a cue for
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* moving to next core. Do a git log of this file for details
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*/
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__asm__ __volatile__(
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" ex %0, [%1] \n"
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: "+r" (val)
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