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    Subject[PATCH 4.14 027/164] spi: Fix scatterlist elements size in spi_map_buf
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    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
    @@ -779,8 +779,14 @@ static int spi_map_buf(struct spi_contro
    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

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