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jeff shia <tshxiayu@gmail.com> wrote: > we use the following to solve the problem of jiffies wraparound. > #define time_after(a,b) \> (typecheck(unsigned long, a) && \ > typecheck(unsigned long, b) && \ > ((long)(b) - (long)(a) < 0)) > #define time_before(a,b) time_after(b,a) [...] > But I cannot understand it has some differences comparing with the > following code.> > /* code 2*/> > unsigned long timeout = jiffies + HZ/2;> > if(timeout < jiffies) > questions:> 1.why the macros of time_after can solve the jiffies wraparound problem? Because the overflows get compensated. It's a property of Galois Fields. > 2.Is there any other possibilities for the "code 2" to overflow > except the jiffies overflow? timeout might overflow, too. -- Ich danke GMX dafür, die Verwendung meiner Adressen mittels per SPF verbreiteten Lügen zu sabotieren. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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