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Unverified Commit ce99319a authored by Maxime Chevallier's avatar Maxime Chevallier Committed by Mark Brown
Browse files

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: default avatarMaxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: default avatarMark 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