On Sat, Mar 09, 2013 at 03:00:54PM -0800, Christopher Li wrote: > On Sat, Mar 9, 2013 at 2:34 PM, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: > > The problems is if we go over the 8k stack. So big arrays are bad. > > Also if the dynamically sized array is inside a loop then normally > > GCC frees it after each iteration, but on some arches it didn't free > > it until after the last iteration. > > So it seems that you agree those variable array usage should be > better change to use kmalloc or some thing. > > > Btw, I've Smatch has cross function analysis, and I'd like to use > > it here to figure out if the max size for dynamically sized arrays. > > I ran into a problem: > > > > The code looks like this: > > char buf[a]; > > The size expression should be an EXPR_SYMBOL, but smatch gets: > > char buf[*a]; > > Sparse currently does not deal with the dynamic array size right now. > It only want to get constant value from the array size. > > The part that evaluate the array size is actually correct. Remember > the EXPR_SYMBOL > actually contain the *address* of symbol "a". So the proper > sizeof(buf) is actually > the content of "*a". That part is fine. It's evaluating it correctly, but Smatch normally expects expressions which haven't been evaluated yet. I can probably hack my own Sparse tree for what I need. It's not a big deal. regards, dan carpenter -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
