multithreading - for a multithreaded singled linked list, is "p && !head.compare_exchange_weak(p,p->next)" atomic? -


the usual implementation popping element in stack data-structure multi-threading is:

void pop() {   auto p = head.load();   while( p && !head.compare_exchange_weak(p,p->next) )     {} }

the 'while idiom' subject fact "these operators (in built-in form) not evaluate second operand if result known after evaluating first."(cf. http://en.cppreference.com/w/cpp/language/operator_logical)

i wondering why can consider whole evaluation of expression 

p && !head.compare_exchange_weak(p,p->next)

as atomic , if not wouldn't possible 'p->next' invalid?

thanks


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