linux-kernel - Re: [linux-stable-rc:linux-4.4.y 1449/1774] drivers/input/joydev.c:485:16: warning: comparison of integer expressions of different signedness: 'int' and 'long unsigned int'

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Message-ID: <20210719071758.GP1931@kadam>
Date:   Mon, 19 Jul 2021 10:17:58 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     kernel test robot <lkp@...el.com>
Cc:     Dan Carpenter <error27@...il.com>, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: Re: [linux-stable-rc:linux-4.4.y 1449/1774]
 drivers/input/joydev.c:485:16: warning: comparison of integer expressions of
 different signedness: 'int' and 'long unsigned int'

On Mon, Jul 19, 2021 at 11:39:16AM +0800, kernel test robot wrote:
>    drivers/input/joydev.c: In function 'joydev_handle_JSIOCSAXMAP':
>    drivers/input/joydev.c:451:16: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
>      451 |  for (i = 0; i < len && i < joydev->nabs; i++) {

We should figure out a way to turn this warning off in the compiler.

It's a stupid warning.  It never fixes any bugs.  It sometimes
introduces bugs.

In the kernel if you are in drivers/ and you have a loop which iterates
over 2 million times that's probably a bug.  But GCC is very very
stupid and not designed to be a static analysis tool.  It does not know
which loops can iterate more than 2 million times.  Even when it knows
that the loop only loops up to 5 or 10 times it still warns that maybe
it will loop over 2 million times.  INSULTS AND DISPARAGEMENT!

Seriously, please disable this warning unless you can point to one
single bug that it has fixed.

regards,
dan carpenter