lkml.org 
[lkml]   [2016]   [Jun]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] dma: xilinx-vdma: add some sanity checks
Date
The newly added xilinx_dma_prep_dma_cyclic function sometimes causes
a gcc warning about the use of the segment function in case
we never run into the inner loop of the function:

dma/xilinx/xilinx_vdma.c: In function 'xilinx_dma_prep_dma_cyclic':
dma/xilinx/xilinx_vdma.c:1808:23: error: 'segment' may be used uninitialized in this function [-Werror=maybe-uninitialized]
segment->hw.control |= XILINX_DMA_BD_SOP;

This can only happen if the period len is zero (which would cause other
problems earlier), or if the buffer is shorter than a period. Neither
of them should ever happen, but by adding an explicit check for these two
cases, we can abort in a more controlled way, and the compiler is
able to see that we never use uninitialized data.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/dma/xilinx/xilinx_vdma.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/dma/xilinx/xilinx_vdma.c b/drivers/dma/xilinx/xilinx_vdma.c
index 0f5b38a0e46f..2ac3253bc823 100644
--- a/drivers/dma/xilinx/xilinx_vdma.c
+++ b/drivers/dma/xilinx/xilinx_vdma.c
@@ -1745,8 +1745,14 @@ static struct dma_async_tx_descriptor *xilinx_dma_prep_dma_cyclic(
int i;
u32 reg;

+ if (!period_len)
+ return NULL;
+
num_periods = buf_len / period_len;

+ if (!num_periods)
+ return NULL;
+
if (!is_slave_direction(direction))
return NULL;

--
2.7.0
\
 
 \ /
  Last update: 2016-06-13 18:01    [W:0.033 / U:0.320 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site