--- Ingo Oeser <[EMAIL PROTECTED]> wrote: > On Sunday, 31. December 2006 14:38, Bernd Petrovitsch wrote: > > That depends on the decision/definition if (so called) "double free" is > > an error or not (and "free(NULL)" must work in POSIX-compliant > > environments). > > A double free of non-NULL is certainly an error. > So the idea of setting it to NULL is ok, since then you can > kfree the variable over and over again without any harm. > > It is just complicated to do this side effect free. > > Maybe one should check for builtin-constant and take the address, > if this is not an builtin-constant. > > sth, like this > > #define kfree_nullify(x) do { \ > if (__builtin_constant_p(x)) { \ > kfree(x); \ > } else { \ > typeof(x) *__addr_x = &x; \ > kfree(*__addr_x); \ > *__addr_x = NULL; \ > } \ > } while (0) > > Regards > > Ingo Oeser >
This is a nice approach but what if someone does kfree_nullify(x+20). I decided to keep it simple. If someone is calling kfree_nullify() with anything other than a simple variable, then they should call kfree(). But definitely an approach that takes care of all situations is the best but I cannot think of a macro that can handle all situations. The simple macro that I sent earlier will catch all the other usage at compile time. Please let me know if I have missed something. -Amit __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/