[bug report] fpga: zynq: Fix incorrect variable type

[bug report] fpga: zynq: Fix incorrect variable type

[Dan Carpenter]

Hello Nava kishore Manne,

The patch ada14a023a64: "fpga: zynq: Fix incorrect variable type"
from Apr 21, 2022, leads to the following Smatch static checker
warning:

	drivers/fpga/zynq-fpga.c:245 zynq_fpga_has_sync()
	warn: impossible condition '(buf[2] == 153) => ((-128)-127 == 153)'

drivers/fpga/zynq-fpga.c
    242 static bool zynq_fpga_has_sync(const char *buf, size_t count)
    243 {
    244         for (; count >= 4; buf += 4, count -= 4)
--> 245                 if (buf[0] == 0x66 && buf[1] == 0x55 && buf[2] == 0x99 &&
                                                                ^^^^^^^^^^^^^^
The patch changed the u8 to char.

The kbuild bot sent an email about this bug on Apr 4 but only Nava was
on the CC and the warning was ignored.  This kind of a dangerous thing,
because I tend to only send warnings once.

https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/4RFIS5FM43D2U26PX7ZL44AFA5RYBWX2/

There is a process issue somewhere.  Why was the linux-fpga@vger.kernel.org
not CC'd on the original report?  Did you deliberately ask to be left
off automated bug reports?

    246                     buf[3] == 0xaa)
    247                         return true;
    248         return false;
    249 }

regards,
dan carpenter

Re: [bug report] fpga: zynq: Fix incorrect variable type

[Xu Yilun]

On Mon, Apr 25, 2022 at 02:36:39PM +0300, Dan Carpenter wrote:
> Hello Nava kishore Manne,
> 
> The patch ada14a023a64: "fpga: zynq: Fix incorrect variable type"
> from Apr 21, 2022, leads to the following Smatch static checker
> warning:
> 
> 	drivers/fpga/zynq-fpga.c:245 zynq_fpga_has_sync()
> 	warn: impossible condition '(buf[2] == 153) => ((-128)-127 == 153)'
> 
> drivers/fpga/zynq-fpga.c
>     242 static bool zynq_fpga_has_sync(const char *buf, size_t count)
>     243 {
>     244         for (; count >= 4; buf += 4, count -= 4)
> --> 245                 if (buf[0] == 0x66 && buf[1] == 0x55 && buf[2] == 0x99 &&
>                                                                 ^^^^^^^^^^^^^^
> The patch changed the u8 to char.
> 
> The kbuild bot sent an email about this bug on Apr 4 but only Nava was
> on the CC and the warning was ignored.  This kind of a dangerous thing,
> because I tend to only send warnings once.
> 
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/4RFIS5FM43D2U26PX7ZL44AFA5RYBWX2/
> 
> There is a process issue somewhere.  Why was the linux-fpga@vger.kernel.org
> not CC'd on the original report?  Did you deliberately ask to be left
> off automated bug reports?

Thanks for the notification. I did't realize that linux-fpga@vger.kernel.org
is out of lkp report, it should not be our intent.

Anything I should do to get back in?

Thanks,
Yilun

> 
>     246                     buf[3] == 0xaa)
>     247                         return true;
>     248         return false;
>     249 }
> 
> regards,
> dan carpenter