Unverified Commit ce99319a authored Mar 02, 2018 by Maxime Chevallier Committed by Mark Brown Mar 02, 2018

spi: Fix scatterlist elements size in spi_map_buf



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: 65598c13 ("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

parent 7928b2cb

drivers/spi/spi.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -779,8 +779,14 @@ static int spi_map_buf(struct spi_controller ctlr, struct device dev,
		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

Admin message