From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Vinod Koul <vkoul@kernel.org>,
Dan Williams <dan.j.williams@intel.com>,
Eugeniu Rosca <erosca@de.adit-jv.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
linux-serial@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
dmaengine@vger.kernel.org,
Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH] dmaengine: rcar-dmac: Reject zero-length slave DMA requests
Date: Mon, 24 Jun 2019 14:38:18 +0200 [thread overview]
Message-ID: <20190624123818.20919-1-geert+renesas@glider.be> (raw)
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: Eugeniu Rosca <erosca@de.adit-jv.com>
Analyzed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
See "[PATCH 0/2] serial: sh-sci: Fix .flush_buffer() issues"
(https://lore.kernel.org/linux-renesas-soc/20190624123540.20629-1-geert+renesas@glider.be/)
for the driver fix.
drivers/dma/sh/rcar-dmac.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 67df54ac329400b7..9c41a4e425759fcc 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -1165,7 +1165,7 @@ 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);
--
2.17.1
next reply other threads:[~2019-06-24 12:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 12:38 Geert Uytterhoeven [this message]
2019-06-24 12:49 ` [PATCH] dmaengine: rcar-dmac: Reject zero-length slave DMA requests Wolfram Sang
2019-06-25 4:38 ` Vinod Koul
2019-06-25 4:40 ` Vinod Koul
2019-06-26 18:14 ` Eugeniu Rosca
2019-06-28 12:10 ` Geert Uytterhoeven
2019-06-28 12:57 ` Wolfram Sang
2019-07-03 15:34 ` Eugeniu Rosca
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