Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1235f5e0 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Greg Kroah-Hartman
Browse files

dmaengine: rcar-dmac: Reject zero-length slave DMA requests 



[ Upstream commit 78efb76ab4dfb8f74f290ae743f34162cd627f19 ]

While the .device_prep_slave_sg() callback rejects empty scatterlists,
it still accepts single-entry scatterlists with a zero-length segment.
These may happen if a driver calls dmaengine_prep_slave_single() with a
zero len parameter.  The corresponding DMA request will never complete,
leading to messages like:

    rcar-dmac e7300000.dma-controller: Channel Address Error happen

and DMA timeouts.

Although requesting a zero-length DMA request is a driver bug, rejecting
it early eases debugging.  Note that the .device_prep_dma_memcpy()
callback already rejects requests to copy zero bytes.

Reported-by: default avatarEugeniu Rosca <erosca@de.adit-jv.com>
Analyzed-by: default avatarYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent f1741424

drivers/dma/sh/rcar-dmac.c

+1 −1
Original line number Diff line number Diff line
@@ -1111,7 +1111,7 @@ rcar_dmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, 
	struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);



	/* Someone calling slave DMA on a generic channel? */

	if (rchan->mid_rid < 0 || !sg_len) {

	if (rchan->mid_rid < 0 || !sg_len || !sg_dma_len(sgl)) {

		dev_warn(chan->device->dev,

			 "%s: bad parameter: len=%d, id=%d\n",

			 __func__, sg_len, rchan->mid_rid);