[PATCH 2/2] mmc: renesas_sdhi: fix kernel panic in _internal_dmac.c

Yoshihiro Shimoda
2017-10-17T07:30:21Z

Since this driver checks if the return value of dma_map_sg() is minus
or not and keeps to enable the DMAC, it may cause kernel panic when
the dma_map_sg() returns 0. So, this patch fixes the issue.

Reported-by: Dirk Behme <dirk.behme@de.bosch.com>
Fixes: 2a68ea7896e3 ("mmc: renesas-sdhi: add support for R-Car Gen3 SDHI DMAC")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
drivers/mmc/host/renesas_sdhi_internal_dmac.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/renesas_sdhi_internal_dmac.c b/drivers/mmc/host/renesas_sdhi_internal_dmac.c
index 6c9b4b2..378fe88 100644
--- a/drivers/mmc/host/renesas_sdhi_internal_dmac.c
+++ b/drivers/mmc/host/renesas_sdhi_internal_dmac.c
@@ -147,11 +147,8 @@
WARN_ON(host->sg_len > 1);

/* This DMAC cannot handle if buffer is not 8-bytes alignment */
- if (!IS_ALIGNED(sg->offset, 8)) {
- host->force_pio = true;
- renesas_sdhi_internal_dmac_enable_dma(host, false);
- return;
- }
+ if (!IS_ALIGNED(sg->offset, 8))
+ goto force_pio;

if (data->flags & MMC_DATA_READ) {
dtran_mode |= DTRAN_MODE_CH_NUM_CH1;
@@ -164,8 +161,8 @@
}

ret = dma_map_sg(&host->pdev->dev, sg, host->sg_len, dir);
- if (ret < 0)
- return;
+ if (ret == 0)
+ goto force_pio;

renesas_sdhi_internal_dmac_enable_dma(host, true);

@@ -177,6 +174,12 @@
dtran_mode);
renesas_sdhi_internal_dmac_dm_write(host, DM_DTRAN_ADDR,
sg->dma_address);
+
+ return;
+
+force_pio:
+ host->force_pio = true;
+ renesas_sdhi_internal_dmac_enable_dma(host, false);
}

static void renesas_sdhi_internal_dmac_issue_tasklet_fn(unsigned long arg)
--
1.9.1