| From ce99319a182fe766be67f96338386f3ec73e321c Mon Sep 17 00:00:00 2001 |
| From: Maxime Chevallier <maxime.chevallier@bootlin.com> |
| Date: Fri, 2 Mar 2018 15:55:09 +0100 |
| Subject: spi: Fix scatterlist elements size in spi_map_buf |
| |
| From: Maxime Chevallier <maxime.chevallier@bootlin.com> |
| |
| 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 <maxime.chevallier@bootlin.com> |
| Signed-off-by: Mark Brown <broonie@kernel.org> |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/spi/spi.c | 10 ++++++++-- |
| 1 file changed, 8 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/spi/spi.c |
| +++ b/drivers/spi/spi.c |
| @@ -743,8 +743,14 @@ static int spi_map_buf(struct spi_master |
| for (i = 0; i < sgs; i++) { |
| |
| if (vmalloced_buf || kmap_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))); |
| if (vmalloced_buf) |
| vm_page = vmalloc_to_page(buf); |
| else |
