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Subject[PATCH] rtc: mcp795: remove VLA usage
Date
In preparation to enabling -Wvla, remove VLAs and replace them with
fixed-length arrays instead.

rtc-mcp795.c uses a variable-length array declaration to contain
the command to write the rtcc; this can be replaced by a fixed-
size array of length 2 (instruction, address) + 32 (data out),
assuming a maximum data length of 32 bytes before wrap up.

This was prompted by https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Stefano Manni <stefano.manni@gmail.com>
---
drivers/rtc/rtc-mcp795.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-mcp795.c b/drivers/rtc/rtc-mcp795.c
index 77f21331ae21..a5f504e2364c 100644
--- a/drivers/rtc/rtc-mcp795.c
+++ b/drivers/rtc/rtc-mcp795.c
@@ -61,6 +61,9 @@

#define SEC_PER_DAY (24 * 60 * 60)

+/* Maximum length for data out in write operation to RTCC */
+#define MCP795_MAX_DATAOUT_LEN 32
+
static int mcp795_rtcc_read(struct device *dev, u8 addr, u8 *buf, u8 count)
{
struct spi_device *spi = to_spi_device(dev);
@@ -82,7 +85,10 @@ static int mcp795_rtcc_write(struct device *dev, u8 addr, u8 *data, u8 count)
{
struct spi_device *spi = to_spi_device(dev);
int ret;
- u8 tx[2 + count];
+ u8 tx[2 + MCP795_MAX_DATAOUT_LEN];
+
+ if (count > MCP795_MAX_DATAOUT_LEN)
+ return -EINVAL;

tx[0] = MCP795_WRITE;
tx[1] = addr;
--
2.14.3
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