3.16.82-rc1 review patch. If anyone has any objections, please let me know.
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From: Peng Fan peng.fan@nxp.com
commit 74887542fdcc92ad06a48c0cca17cdf09fc8aa00 upstream.
Per Documentation/DMA-API-HOWTO.txt, To unmap a scatterlist, just call: dma_unmap_sg(dev, sglist, nents, direction);
.. note::
The 'nents' argument to the dma_unmap_sg call must be the _same_ one you passed into the dma_map_sg call, it should _NOT_ be the 'count' value _returned_ from the dma_map_sg call.
However in the driver, priv->nent is directly assigned with value returned from dma_map_sg, and dma_unmap_sg use priv->nent for unmap, this breaks the API usage.
So introduce a new entry orig_nent to remember 'nents'.
Fixes: da3564ee027e ("pch_uart: add multi-scatter processing") Signed-off-by: Peng Fan peng.fan@nxp.com Link: https://lore.kernel.org/r/1573623259-6339-1-git-send-email-peng.fan@nxp.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/tty/serial/pch_uart.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/tty/serial/pch_uart.c +++ b/drivers/tty/serial/pch_uart.c @@ -251,6 +251,7 @@ struct eg20t_port { struct dma_chan *chan_rx; struct scatterlist *sg_tx_p; int nent; + int orig_nent; struct scatterlist sg_rx; int tx_dma_use; void *rx_buf_virt; @@ -803,9 +804,10 @@ static void pch_dma_tx_complete(void *ar } xmit->tail &= UART_XMIT_SIZE - 1; async_tx_ack(priv->desc_tx); - dma_unmap_sg(port->dev, sg, priv->nent, DMA_TO_DEVICE); + dma_unmap_sg(port->dev, sg, priv->orig_nent, DMA_TO_DEVICE); priv->tx_dma_use = 0; priv->nent = 0; + priv->orig_nent = 0; kfree(priv->sg_tx_p); pch_uart_hal_enable_interrupt(priv, PCH_UART_HAL_TX_INT); } @@ -1030,6 +1032,7 @@ static unsigned int dma_handle_tx(struct dev_err(priv->port.dev, "%s:dma_map_sg Failed\n", __func__); return 0; } + priv->orig_nent = num; priv->nent = nent;
for (i = 0; i < nent; i++, sg++) {