From 0b8053fef6f71db8e09c7dcdf8fd1b2cd5d53756 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 25 Feb 2016 21:47:57 +0100 Subject: [PATCH] serial: ifx6x60: avoid uninitialized variable use gcc warns about a potential use of an uninitialized variable in this driver: drivers/tty/serial/ifx6x60.c: In function 'ifx_spi_complete': drivers/tty/serial/ifx6x60.c:713:6: warning: 'more' may be used uninitialized in this function [-Wmaybe-uninitialized] if (more || ifx_dev->spi_more || queue_length > 0 || Unlike a lot of other such warnings, this one is correct and describes an actual problem in the handling of the "IFX_SPI_HEADER_F" result code. This appears to be a result from a restructuring of the driver that dates back to before it was merged in the kernel, so it's impossible to know where it went wrong. I also don't know what that result code means, so I have no idea if setting 'more' to zero is the correct solution, but at least it makes the behavior reproducible rather than depending on whatever happens to be on the kernel stack. This patch initializes the 'more' variable to zero in each of the three code paths that could result in undefined behavior before, which is more explicit than initializing it at the start of the function. Signed-off-by: Arnd Bergmann Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/ifx6x60.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/serial/ifx6x60.c b/drivers/tty/serial/ifx6x60.c index 88246f7e435a..2085a6cfa44b 100644 --- a/drivers/tty/serial/ifx6x60.c +++ b/drivers/tty/serial/ifx6x60.c @@ -395,8 +395,10 @@ static int ifx_spi_decode_spi_header(unsigned char *buffer, int *length, if (h1 == 0 && h2 == 0) { *received_cts = 0; + *more = 0; return IFX_SPI_HEADER_0; } else if (h1 == 0xffff && h2 == 0xffff) { + *more = 0; /* spi_slave_cts remains as it was */ return IFX_SPI_HEADER_F; } @@ -688,6 +690,7 @@ static void ifx_spi_complete(void *ctx) ifx_dev->rx_buffer + IFX_SPI_HEADER_OVERHEAD, (size_t)actual_length); } else { + more = 0; dev_dbg(&ifx_dev->spi_dev->dev, "SPI transfer error %d", ifx_dev->spi_msg.status); }