Following code contains function called SafeSum which is ensuring the consistency of shared data sum. Assume that Safesum function can be called by several of thread and doesnt aliow sum become in inconsistent state. Put pthread mutex lock and pthread mutex$\_$unlock functions into critical sections of following code.

phread$\_$mutex$\_$I mutex $=$ PTHREAD$\_$MUTEX$\_$IMTIALIZER,

int sum $=0,r$ Global variables $7$

void 'SafeSum$($void$)$

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int $1.$

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return NULL

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