Hi Herbert, On Sun, Nov 13, 2016 at 07:45:32PM +0800, Herbert Xu wrote: > +int skcipher_walk_done(struct skcipher_walk *walk, int err) > +{ > + unsigned int nbytes = 0; > + unsigned int n = 0; > + > + if (likely(err >= 0)) { > + n = walk->nbytes - err; > + nbytes = walk->total - n; > + } > + > + if (likely(!(walk->flags & (SKCIPHER_WALK_PHYS | > + SKCIPHER_WALK_SLOW | > + SKCIPHER_WALK_COPY | > + SKCIPHER_WALK_DIFF)))) { > +unmap_src: > + skcipher_unmap_src(walk); Isn't it wrong to unmap the buffers when err < 0? They won't have been mapped yet, e.g. if the 'skcipher_walk_done(walk, -EINVAL)' case is hit. > + /* Short-circuit for the common/fast path. */ > + if (!(((unsigned long)walk->iv ^ (unsigned long)walk->oiv) | > + ((unsigned long)walk->buffer ^ (unsigned long)walk->page) | > + (unsigned long)walk->page)) > + goto out; This is really saying that the IV wasn't copied and that walk->buffer and walk->page are both NULL. But if walk->buffer is NULL then the IV wasn't copied. So this can be simplified to: if (!((unsigned long)walk->buffer | (unsigned long)walk->page)) goto out; > +int skcipher_walk_next(struct skcipher_walk *walk) > +{ Shouldn't this be static? There's even a static declaration earlier in the file. > +static int skcipher_next_slow(struct skcipher_walk *walk) > +{ > + bool phys = walk->flags & SKCIPHER_WALK_PHYS; > + unsigned alignmask = walk->alignmask; > + unsigned bsize = walk->chunksize; ... > + walk->nbytes = bsize; skcipher_next_slow() is always setting up 'chunksize' bytes to be processed. Isn't this wrong in the 'blocksize < chunksize' case because fewer than 'chunksize' bytes may need to be processed? > +static inline void *skcipher_map(struct scatter_walk *walk) > +{ > + struct page *page = scatterwalk_page(walk); > + > + return (PageHighMem(page) ? kmap_atomic(page) : page_address(page)) + > + offset_in_page(walk->offset); > +} Is the PageHighMem() optimization really worthwhile? It will skip kmap_atomic() and hence preempt_disable() for non-highmem pages, so it may make it harder to find bugs where users are sleeping when they shouldn't be. It also seems inconsistent that skcipher_map() will do this optimization but scatterwalk_map() won't. > + if (!walk->page) { > + gfp_t gfp = skcipher_walk_gfp(walk); > + > + walk->page = (void *)__get_free_page(gfp); > + if (!walk->page) > + goto slow_path; > + } > + > + walk->nbytes = min_t(unsigned, n, > + PAGE_SIZE - offset_in_page(walk->page)); walk->page will be page-aligned, so there's no need for offset_in_page(). Also, 'n' has already been clamped to at most one page. So AFAICS this can simply be 'walk->nbytes = n;'. > +int skcipher_walk_done(struct skcipher_walk *walk, int err); ... > +void skcipher_walk_complete(struct skcipher_walk *walk, int err); The naming is confusing: "done" vs. "complete". They can easily be mixed up. Would it make more sense to have something with "async" in the name for the second one, like skcipher_walk_async_done()? Eric -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html