On Thu, Jun 04, 2026 at 03:36:48PM -0400, David Hu wrote: > On Thu, Jun 4, 2026 at 5:43 AM Leon Romanovsky <[email protected]> wrote: > > > > On Mon, Jun 01, 2026 at 08:00:12PM +0000, David Hu wrote: > > > @@ -36,7 +36,7 @@ static unsigned int calc_sg_nents(struct dma_iova_state > > > *state, > > > struct phys_vec *phys_vec, size_t > > > nr_ranges, > > > size_t size) > > > { > > > - unsigned int nents = 0; > > > + size_t nents = 0; > > > size_t i; > > > > > > if (!state || !dma_use_iova(state)) { > > > @@ -51,6 +51,9 @@ static unsigned int calc_sg_nents(struct dma_iova_state > > > *state, > > > nents = DIV_ROUND_UP(size, UINT_MAX); > > > } > > > > > > + if (nents > UINT_MAX) > > > > I would suggest to use check_add_overflow() while calculating nents > > instead of this check. > > Hi Leon, > > Thank you for the review. Using `check_add_overflow()` is a great > suggestion and definitely > cleaner for the accumulation loop. I'll update this for v6. > > > > @@ -133,6 +137,11 @@ struct sg_table *dma_buf_phys_vec_to_sgt(struct > > > dma_buf_attachment *attach, > > > } > > > > > > nents = calc_sg_nents(dma->state, phys_vec, nr_ranges, size); > > > + if (!nents) { > > > + ret = -EINVAL; > > > + goto err_free_state; > > > + } > > > > Technically, this hunk is not necessary, since sg_alloc_table() will > > return -EINVAL when nents == 0. At least, that is the behavior I relied on. > > I originally added this explicit check in v5 to address Jason's > feedback, and to make the > failure explicit rather than relying on `sg_alloc_table()` failing > silently on `nents=0`.
I prefer explicit checks, but I am not in favor of duplicating them. Since sg_alloc_table() already validates this condition, we do not need to repeat the same check in dma-buf. A comment should be sufficient to inform future reviewers that nents == 0 is already handled. Thanks > > Jason, do you have a strong preference here? I am happy to drop the > hunk and rely on > `sg_alloc_table()` returning `-EINVAL` if you are both comfortable with that. > > Thanks, > David
