这里4种例子都有，研究一下对不对
https://en.m.wikipedia.org/wiki/Reentrancy_(computing)

还有人给了个汉诺塔的例子：
https://stackoverflow.com/questions/9116598/why-is-this-code-reentrant-but-not-thread-safe

Reentrant but not thread-safe

The following (somewhat contrived) modification of the swap function, which is careful to leave the global data in a consistent state at the time it exits, is reentrant; however, it is not thread-safe, since there are no locks employed, it can be interrupted at any time:

int tmp;

void swap(int* x, int* y)
{
    /* Save global variable. */
    int s;
    s = tmp;

    tmp = *x;
    *x = *y;      /*If hardware interrupt occurs here then it will fail to keep the value of tmp. So this is also not a reentrant example*/
    *y = tmp;     /* Hardware interrupt might invoke isr() here. */

    /* Restore global variable. */
    tmp = s;
}

void isr()
{
    int x = 1, y = 2;
    swap(&x, &y);
}


【 在 wjhtingerx 的大作中提到: 】
: rt
--
修改:z16166 FROM 123.118.187.*
FROM 123.118.187.*