On Sat, 2018-11-17 at 12:40 +0530, Souptick Joarder wrote: > Hi Joe, Hi back.
> On Fri, Nov 16, 2018 at 12:55 AM Joe Perches <j...@perches.com> wrote: > > On Thu, 2018-11-15 at 23:29 +0530, Sabyasachi Gupta wrote: > > > On Mon, Nov 5, 2018 at 8:58 AM Sabyasachi Gupta > > > <sabyasachi.li...@gmail.com> wrote: > > > > Replaced dma_alloc_coherent + memset with dma_zalloc_coherent > > > > > > > > Signed-off-by: Sabyasachi Gupta <sabyasachi.li...@gmail.com> > > > > > > Any comment on this patch? > > > > It's obviously correct. > > > > You might realign the arguments on the next lines > > to the open parenthesis. > > > > Perhaps there should be new function calls > > added for symmetry to the other alloc functions > > for multiplication overflow protection. > > > > Perhaps: > > > > void *dma_alloc_array_coherent() > > void *dma_calloc_coherent() > > > > Something like > > --- > > include/linux/dma-mapping.h | 19 +++++++++++++++++++ > > 1 file changed, 19 insertions(+) > > > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > > index 15bd41447025..95bebf8883b1 100644 > > --- a/include/linux/dma-mapping.h > > +++ b/include/linux/dma-mapping.h > > @@ -565,6 +565,25 @@ static inline void *dma_alloc_coherent(struct device > > *dev, size_t size, > > (gfp & __GFP_NOWARN) ? DMA_ATTR_NO_WARN : 0); > > } > > > > +static inline void *dma_alloc_array_coherent(struct device *dev, > > + size_t n, size_t size, > > + dma_addr_t *dma_handle, gfp_t > > gfp) > > +{ > > + size_t bytes; > > + > > + if (unlikely(check_mul_overflow(n, size, &bytes))) > > + return NULL; > > + return dma_alloc_coherent(dev, bytes, dma_handle, gfp); > > +} > > + > > +static inline void *dma_calloc_coherent(struct device *dev, > > + size_t n, size_t size, > > + dma_addr_t *dma_handle, gfp_t gfp) > > +{ > > + return dma_alloc_array_coherent(dev, n, size, dma_handle, > > + gfp | __GFP_ZERO); > > +} > > + > > If I understood correctly, you are talking about adding these 2 new inline > functions. We can do that. > > Can you please help to understand the consumers of these 2 new inline ? Any call to dma_alloc_coherent with a multiply _might_overflow the multiplication. The check_mul_overflow simply avoids the overflow.