On Mon, 12 Jan 2015 21:45:58 +0100 Geert Uytterhoeven <[email protected]> wrote:
> On Mon, Jan 12, 2015 at 10:18 AM, Andrzej Hajda <[email protected]> wrote: > > kstrdup if often used to duplicate strings where neither source neither > > destination will be ever modified. In such case we can just reuse the source > > instead of duplicating it. The problem is that we must be sure that > > the source is non-modifiable and its life-time is long enough. > > > > I suspect the good candidates for such strings are strings located in kernel > > .rodata section, they cannot be modifed because the section is read-only and > > their life-time is equal to kernel life-time. > > > > This small patchset proposes alternative version of kstrdup - kstrdup_const, > > which returns source string if it is located in .rodata otherwise it > > fallbacks > > to kstrdup. > > It also introduces kfree_const(const void *x). > > As kfree_const() has the exact same signature as kfree(), the risk of > accidentally passing pointers returned from kstrdup_const() to kfree() seems > high, which may lead to memory corruption if the pointer doesn't point to > allocated memory. Yes, it's an ugly little patchset. But 100-200k of memory is hard to argue with, and I'm not seeing a practical way of getting those savings with a cleaner approach. Hopefully a kfree(rodata-address) will promptly oops, but I haven't tested that and it presumably depends on which flavour of slab/sleb/slib/slob/slub you're using. -- 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/
