Messages in this thread | | | Date | Fri, 17 Sep 2010 11:55:23 -0700 | From | Randy Dunlap <> | Subject | Re: A simple question of sys_ |
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On Fri, 17 Sep 2010 14:58:30 +0800 Rofail Qu wrote:
> How to use macro IS_ERR() ? > > It defines as, > ... > #define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO) > static inline long __must_check IS_ERR(const void *ptr) > { > return IS_ERR_VALUE((unsigned long)ptr); > } > ... > so when pass x as a pointer and x>=-MAX_ERRNO (including NULL or any > valid address), > IS_ERR() will return true!
Since your conclusion is false, some part of your premise must have a problem. Can you find it?
> IS_ERR(x) seems to use on judge if "x" is a valid error number, right?
Yes, that's what it is for.
> So in sys_execve(), > ... > long error; > char* filename; > > filename = getname(name); > error = PTR_ERR(filename); > if (IS_ERR(filename)) // <== should be IS_ERR((void *)error) or other? > return error; > error = do_execve(filename, argv, envp, regs); > ... > > Where i am wrong?
--- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code ***
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