On Fri, Jul 20, 2018 at 08:23:44PM +0100, Ben Hutchings wrote: > On Sun, 2018-07-01 at 18:02 +0200, Greg Kroah-Hartman wrote: > > 4.4-stable review patch. If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Maxime Chevallier <[email protected]> > > > > commit ce99319a182fe766be67f96338386f3ec73e321c upstream. > > > > When SPI transfers can be offloaded using DMA, the SPI core need to > > build a scatterlist to make sure that the buffer to be transferred is > > dma-able. > > > > This patch fixes the scatterlist entry size computation in the case > > where the maximum acceptable scatterlist entry supported by the DMA > > controller is less than PAGE_SIZE, when the buffer is vmalloced. > > > > For each entry, the actual size is given by the minimum between the > > desc_len (which is the max buffer size supported by the DMA controller) > > and the remaining buffer length until we cross a page boundary. > > > > Fixes: 65598c13fd66 ("spi: Fix per-page mapping of unaligned vmalloc-ed > > buffer") > > Signed-off-by: Maxime Chevallier <[email protected]> > > Signed-off-by: Mark Brown <[email protected]> > > Cc: [email protected] > > Signed-off-by: Sudip Mukherjee <[email protected]> > > Signed-off-by: Greg Kroah-Hartman <[email protected]> > > --- > > drivers/spi/spi.c | 10 ++++++++-- > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > > --- a/drivers/spi/spi.c > > +++ b/drivers/spi/spi.c > > @@ -707,8 +707,14 @@ static int spi_map_buf(struct spi_master > > for (i = 0; i < sgs; i++) { > > > > if (vmalloced_buf) { > > - min = min_t(size_t, > > - len, desc_len - offset_in_page(buf)); > > + /* > > + * Next scatterlist entry size is the minimum between > > + * the desc_len and the remaining buffer length that > > + * fits in a page. > > + */ > > + min = min_t(size_t, desc_len, > > + min_t(size_t, len, > > + PAGE_SIZE - offset_in_page(buf))); > > vm_page = vmalloc_to_page(buf); > > if (!vm_page) { > > sg_free_table(sgt); > > I think this makes sense upstream, but in 4.4 it seems to be a no-op > since desc_len is always set to PAGE_SIZE when vmalloced_buf is true. > This fix depends on (at least) commit df88e91bbfd1 "spi: respect the > maximum segment size of DMA device" which went into 4.6.
Good catch. I'll leave it as-is for now though. thanks, greg k-h
